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MindMap Gallery Epidemiology
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Epidemiology
A complete and comprehensive version, it contains formulas to help memory, detailed introduction, and comprehensive description. I hope it can help interested friends learn.
Edited at 2023-11-24 17:16:38
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Epidemiology
- bacteria
This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
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- Outline
Epidemiology
introduction
Definition and interpretation of epidemiology
Study the distribution of diseases and health conditions in the population and their influencing factors Strategies and measures to prevent diseases and promote health
Three levels of research content
disease, health, injury
Three stages of research tasks
Reveal phenomena, find out causes, and provide measures
Three research methods
Observation, experiment, mathematics
Three major elements
Principles, methods, applications
principle
The relationship between humans and the environment (ecology of disease)
multi-causalism
Etiology inference
Causes and inferences
The pathogenesis of the disease
Distribution of diseases in the population
disease prevention
Mathematical models of disease development
Research methods
Observation
describe
case control
queue
Experimental Method
Experimental Study
Theoretical method
theoretical epidemiology
Construction and evaluation of disease early warning prediction models
application
Research on causes and risk factors
natural history
In-depth research
disease surveillance
Disease prevention and health promotion
regular practice
Evaluation of the effectiveness of disease prevention and treatment
feature
Groups, comparison, probability theory and mathematical statistics, prevention first, development, social psychology
Challenges and prospects
Pay equal attention to macro and micro
Communicable and non-communicable diseases
Health protection and health promotion
field epidemiology
Emergencies
ethics
individual genetic information
Special diseases such as AIDS
Role in the evidence-based wave
Distribution of disease
A measure of disease frequency
Frequency of disease
Incidence
The frequency of new cases of a certain disease among a certain period of time, a certain range, and a certain population
application
epidemic intensity of disease
Reflects the impact of disease on population health
Compare - popular characteristics, explore causes, evaluate effects
Calculation considerations
Number of new cases
Multiple episodes of illness for one person are counted as multiple
Exposed population
People who are already sick cannot become newly ill or be vaccinated to obtain lasting immunity.
Observation time
incidence rate
Different composition ratios and standardized processing
Attack rate
Incidence rate in a certain limited range and within a short period of time
Outbreaks of food poisoning, occupational poisoning, and infectious diseases
Renewal rate
Second generation incidence rate, infectious disease shortest to longest incubation period Susceptible contacts Incidence-all
The strength of infectiousness, analysis of epidemic factors, and evaluation of the effectiveness of epidemic prevention measures
Frequency of illness
Prevalence
Prevalence rate, new and old cases in the total population within a specific period of time; time point, period
application
Current disease status, long course of disease-prevalence situation
Severity of hazards to residents’ health
health economics evaluation
Influencing factors
population changes
Rise in new cases
Fewer new cases
case migration
Case migration
Susceptible people move in
Healthy people move out
Healthy people move in
hospital capacity
Improved diagnosis and treatment levels
Improved cure rate
Increased reporting rates
How quickly the patient dies
patient saved from death However, the course of the disease is prolonged if it is not cured
Shorten the course of disease
Extended lifespan without cure
Increased case fatality rate
Differences and connections with morbidity
molecular
Denominator
source
Current situation investigation and screening
Disease surveillance, case reports, cohorts
Applicable diseases
Chronic disease/long course of disease
various diseases
Observation time
application
Influencing factors
More
Fewer, prevalence, diagnosis level, reporting quality
feature
relation
Suffering=onset*course of disease
infection rate
The number of people currently infected with a certain pathogen among the people being tested within a certain period of time
Infectious diseases, parasitic diseases
Death and Survival Frequency
mortality rate
The total number of deaths in a certain group of people during a certain period of time
application
total death level
Health status and health care work
Mortality rate - causes and prevention measures
Morbidity (high case fatality rate)
case fatality rate
Number of deaths due to a disease within a certain period of time
application
Severity of disease, medical level, diagnosis and treatment capabilities
Pay attention to comparability when evaluating medical level
infant mortality
Number of deaths under one year old after birth Number of births
application
Measure the quality of the population—medical and health conditions, social and economic strength, people’s living standards, and scientific and technological development levels
Health status and quality of life-maternal and child health care level
survival rate
Number of patients still alive after several years of follow-up
application
How harmful the disease is to life
Long-term effects of long-term disease
disease burden
Potential years of life lost
The sum of the differences between the life expectancy of people who die from a certain disease and a certain age group - the actual age at death
application
Measuring disease burden - the years lost due to death, emphasizing the cost of premature death to a population's health
Comparing diseases - degree of harm
Compare regions/time-characteristics/trends
Comparing causes of death – age group focus
Disability Adjusted Life Years
Total healthy life years lost from onset to death (premature death - years of life lost; disability - years of lost healthy life)
application
Comparing diseases - degree of harm
Comparing regions – changing trends
Sorting by size - main diseases, key population areas
health economics evaluation
epidemic intensity of disease
Distribute
There is no obvious relationship between levels, time and location over the years.
Common situations
Long-lasting immunity, mainly invisible infections, difficult transmission mechanism, and long incubation period
outbreak
Local area/collective unit, short period of time, many symptoms are the same, and the same transmission route of infection source
Popularity
Significantly exceeding the level of previous years, showing obvious time and space connections
Pandemic
Significantly spread rapidly, involve a wide area, and cross provincial boundaries, national boundaries and even continental boundaries in a short period of time
distributed
crowd
inherent characteristics or social characteristics
How to analyze age distribution
cross-sectional study
Different age groups in the same period/different age groups in different years
Infectious diseases and short incubation period
birth cohort analysis
A group of people born in the same period
Long-term trends in age distribution
area
Between countries and different regions within countries
Urban and rural distribution
City - respiratory tract
Township-intestine
regional agglomeration
The frequency of disease in a certain area is higher than that of surrounding/causing factors
Classification
local
statistical locality
Social factors (hygienic conditions, economic conditions; dysentery)
natural endemic
Pathogens - Schistosoma, filarial worms
Trace elements-endemic goiter
natural foci
Pathogen does not depend on people, wildlife or domestic animals for reproduction - forest encephalitis
imported disease
Does not exist/has been eliminated in this country and this region, abroad/other regions
Basis for judging endemic diseases
This area/other areas/immigration/immigration/susceptible animals
time
short term fluctuations
Disease epidemic/outbreak
Large numbers of people are exposed simultaneously or continuously to a common disease-causing agent
food poisoning in collective canteen
Seasonal
Strictly seasonal
Mostly concentrated in a few months, not in other months
Insect vector transmission
seasonal increase
The disease occurs all year round, and the incidence rate only increases in certain months.
Intestine (summer and autumn) Respiratory tract (winter and spring)
cyclical
Disease frequency, regular intervals, ups and downs - every few years, epidemic peaks
Accumulation of susceptible individuals, transmission conditions, immunity, pathogen mutation
long term trend
Years or decades, clinical characteristics/distribution/epidemic intensity
Causes, pathogens, immunity, medical level, report registration
immigration epidemiology
Comprehensive description of the three distributions, immigration, place of residence, and place of original residence-environment/genetics
Causes, findings and inferences
Basic concepts of causes
Cause
Causes of disease - factors or events that affect future disease occurrence
causation
Basic conditions
Chronologically
cause-before/effect-after
connection relation
Effect time - changes due to changes in events
due to sex change
Consequential event - caused by a causal event
Diversity
Single cause and single effect
a cause - a disease
Single cause and multiple effects
Pleiotropic effects of causes - blocking a certain cause and preventing multiple diseases
Multiple causes and single effect
Multiple causes of disease - multi-pronged approach to disease control
Multiple causes and multiple effects
Complexity, Uncertainty-Multiple Ways to Prevention
direct cause
eventually causing disease
indirect cause
before direct cause
Types of causation in medical practice
Diseases and causes
Treatments and Results
Treatment and side effects
Etiological theories and etiological models
Uses of etiology models
Explain the relationship between causes/causes and diseases
Indicates the direction of causes - reveals new causes
The role of etiology, concepts and principles of epidemiology
Main etiological models
Triangular model of infectious disease epidemics
host, pathogen, environment
Uncovering factors other than pathogens that prevent and control infectious diseases Unknown cause - Possibility of preventing infectious diseases
wheel model
Middle-genetic core/surrounding-physical and social environment
Primary and secondary differences - direct cause, indirect cause/distal cause, proximal cause Transition models for studying the causes of chronic disease
An ecological model of the determinants of health
Ecological etiology model, further development of the wheel model
Broaden the scope and field of causes
Cause chain
Occurring sequentially in time, causing each other/between the cause and the final disease
Removing one cause can cut off the entire chain of causes A disease may have multiple independent/interacting causal chains
etiology network
Multiple independent/interrelated causal chains - interconnected, intertwined
The role of different causal chains - effective prevention and cutting off the main causal chains Cut off multiple at the same time - prevent more
sufficient etiology-component etiology model
sufficient cause
formation-disease occurrence
component etiology
One or more - sufficient cause, missing component cause - disease ❌
complementary causes
component causes of sufficient causes sufficient cause of the same disease
Necessary cause
Component causes required by all sufficient causes, do not exist - Sufficient Cause ❌ - Disease ❌
Discover and verify causes and causal inferences
Mill's law of causal inference
seek common ground
Different occasions - all conditions are different except one is the same
Case Series - Factors Shared by Patients
seek differences
Everything is the same except for one difference - the reason for this phenomenon
Case control: patients have, non-patients lack
Seeking common ground while sharing differences
There is only one common occasion when the phenomenon occurs; there is no occasion when the phenomenon does not occur.
Case-control/cohort study
Change together
When one phenomenon changes, another phenomenon changes accordingly
dose response relationship
Remaining
Phenomenon - some composite cause, minus the parts that have been confirmed to be causally linked
Speculation on the cause of individual cases and speculation on the main etiology
general principles of scientific inference
three levels
Inferences within a single study (authenticity)
evaluate
Internal authenticity: how close the research results are to reality Difference Between Observation and Reality - Bias/Systematic Error
Factors affecting research quality
type of study design
General bias control measures
Accuracy of data collection, consistency of measurements between groups, reduction of loss to follow-up, sample representativeness
Unique bias control measures
Random grouping, group concealment, blinding
Sample size - Sampling error - Precision
Methods for evaluating research quality
Research design type
Grading of evidence: cohort studies, case-control, cross-sectional, case series
The amount/rigor of bias control measures
Inferences based on all existing similar studies
Inferences based on all relevant evidence
evidence-based medicine
two aspects
Quantitative
Qualitative
Hill's criteria for inferring etiology
Chronologically
Association strength
dose response relationship
Available in-house Necessary specific conditions
biological consistency
biological plausibility
Result consistency
experimental evidence
Use experimental research to verify and conduct clinical trials to verify
similarity
There is a known similar causal link
specificity
A cause causes a disease
Predictive power
Necessarily non-specific, consistency of results is most important A box of fruits looks like something strange
Specific steps for causal inference
Descriptive research, establishing hypotheses
Analytical research, testing hypotheses
Experimental research to test hypotheses
Causal derivation
Eliminate random error, spurious correlation, indirect correlation, and confounding bias Hill's criterion for determining cause and effect
observed association
encounter association (Random error)
Statistical correlation
false association (Select Measurement Bias)
secondary association
indirect association (confounding bias)
real correlation (causal inference)
descriptive research
Overview
Data obtained from routine surveillance or special surveys - grouping - description of distribution - comparative analysis - three characteristics - clues to the cause
type
Current situation survey
Specific point in time, specific scope - distribution of disease or health conditions and related factors - data collection and description - clues to the cause
ecological research
Correlation studies, group level, E-D
Follow-up
Longitudinal study, regular follow-up - fixed population, dynamic changes
Case
The scene of the disease - contact history, status of family members and surrounding people, environmental factors - causes and conditions of the disease - control - prevention
Case Reports
Detailed introduction to rare diseases, qualitative
single patient
case series
A group of identical diseases-organizing, counting, analyzing, summarizing, and drawing conclusions
Historical data analysis
retrospective survey
Features
Observations are not random
Start with no controls
Temporal relationship-limitations, comparative analysis, providing clues
use
Describe the distribution, occurrence and development of diseases or health conditions
Obtain clues to the cause and propose a hypothesis of the cause
Current situation survey
Features
Start with no controls
Specific time E-D
causal link
Intrinsic exposure factors - gender, race, blood type
Present-past exposure
Relevant/Changing Trends/Past Extremely Unreliable
use
Identify high-risk groups
Distribution - clues to etiology
Evaluate the effectiveness of disease surveillance, vaccination and other measures
Design and Implementation Steps
Research purposes
Type of Study
census
Comprehensive survey, all people
Purpose: Three mornings, distribution, normal value range, residents’ health level
Sampling error, distribution of multiple diseases discovered simultaneously, total cases
Low prevalence, heavy workload, extensive personnel involvement, and high cost
sample survey
Random sampling, representative sample-population
Saving, small scope, meticulous
It is not suitable for cases with low prevalence, excessive variation or general census, complex design and implementation data analysis, duplication or omission.
Research object
Inclusion and exclusion criteria
Sample size and sampling method
Factors affecting sample size
Expected prevalence rate, significance level, allowable error
Sampling method
simple random sampling
The simplest and most basic
When the total number is large
system
Don’t know the overall population (on-site crowd)/each unit within the overall population - good representation
cyclical
layered
Homogeneity within strata - small sampling error
Many layers - improper selection of indicators
whole group
Easy to organize and save / small difference between groups, many groups - high accuracy
Large sampling error, sample size - purely random ➕1/2
multi-stage
data collection
Data collection content, investigator training (quality control), collection method (questionnaire)
Data compilation and analysis
Common biases and controls
bias
Research results and real situation - tendency difference
Research design implementation, data processing and analysis-systematic error Interpretation and inference of results - one-sidedness
Mischaracterization of the link between exposure and disease
common bias
selection bias
Subjective selection of research subjects
arbitrary transformation sampling method
non-response bias
survivorship bias
information bias
reporting bias
Respondents’ answers were inaccurate
recall bias
survey bias
Investigators consciously delve into or do not pay attention to
measurement bias
Measuring tools and inspection methods
confounding bias
control
randomization
compliance
Choose the right statistical method
Investigator training
Data review and review
Correct selection of measurement tools and detection methods
Follow-up unified training retest
Unfortunately, the director reported back to the investigation
Advantages and Disadvantages
excellent
Random sampling - promotion significance and high credibility
After data collection, whether sick or exposed - grouping - natural contemporaneous control and comparability from the same group
Questionnaires, laboratory tests to collect data - multiple factors
Sampling, grouping, data collection
lack
Timing
incubation period
Mistaking normal people-underestimating the level of disease
Incidence
ecological research
Features
in groups
Unable to know the causal link between individual exposure and effects
Descriptive research with broad strokes - explores causes, provides incomplete information
type
ecological comparative study
Distribution-difference-hypothesis of a certain disease among different groups of people or regions
Ecological Trend Research
Continuous observation of the average exposure level of a certain factor before and after changes - changes in morbidity and mortality
use
Clues and hypotheses about etiology
The effectiveness of the intervention
Monitor disease trends
Advantages and Disadvantages
excellent
Save people time and get results faster
Individual dose cannot be measured
only option
The studied factors have a small range of variation in the population
Provide clues to the causes of diseases with unknown causes
most salient features
Evaluation of the effectiveness of interventions
Monitor disease trends
Province, applicable 3, purpose 2
lack
ecological fallacy
Lack of data on the joint distribution of exposure to outcomes at the individual level
Unable to control for suspected confounders
Not an individual’s actual exposure
Cause - non-individual
mixed factors
It is difficult to determine the causal relationship between two variables
Screening
Overview
concept
Preclinical/Early Stage - Quick and easy laboratory tests - Undetected or undiagnosed, apparently healthy but may be diseased or defective - Identification
time, method, object
Purpose
high risk groups
primary prevention
Hidden cases
secondary prevention
Natural history reveals disease iceberg phenomenon
Reasonable allocation of limited health resources
type
scope
whole group
High incidence - all subjects
Selectivity
high risk groups
How many projects
Single item
One project, one disease
Multiple
One more
Multiple diseases
The same group of people - multiple diseases (two cancer screenings)
Purpose
Therapeutic
breast cancer
preventive
Hypertension-stroke
organizational form
initiative
Mobilizing the masses – dedicated locations
opportunistic
Medical consultation - first consultation for non-specialist hypertension
Implementation principles
Screening diseases
Major public health issues, prevalence and mortality ⬆️
Clear natural history - long enough preclinical period, early diagnostic methods, early intervention is better than late intervention
Have a clear understanding of the intervention effects and adverse reactions at different stages
screening test
Simple, cheap, fast, safe, acceptable
Different levels of economic development and health resources - method selection
disease treatment
There are effective treatments at different stages, sooner rather than later
Screening project implementation plan and evaluation
Target Population (Identified?) Screening-Treatment Program (Effective?) Population Benefits
health economics evaluation
Evaluation of screening tests
Screening test definition, characteristics
Methods to identify apparent health - possible diseases/risks (questionnaires, physical examinations, endoscopy and x-ray examinations, biomarker testing)
recognition methods
Simple, cheap, safe, fast, acceptable
Differences from diagnostic tests
Purpose
May be sick/not sick
Patient/Suspected to be sick but not actually
object
Appearance healthy/asymptomatic
Patient/Screening
feature
Order, price, full range, speed, available
accuracy, authority
result
/-
Case/non-case
cost
Economical and cheap
More expensive
deal with
further diagnosis
Close observation and treatment
Contents and Characteristics of Research Design
Comparative study-the degree of consistency between screening results and gold standard judgment results
Taking the hospital as the scene
case-noncase approach
Determining the gold standard - recognized as the most accurate and reliable method
Choose research subjects
random sampling
Cases - mild early symptoms/various clinical types
Non-case - non-patient/easily confused with the target disease
sample size
Sensitivity, specificity, testability level, tolerance
Determining cutoff values for screening outcome classification criteria
Blind measurement
Control information bias
The case/non-case ratio cannot represent the ratio of currently affected/unaffected people in the target population Predictive values cannot be calculated directly
Taking the community as the scene
cross-sectional design
Select a representative sample of the target population and use screening/gold standard-blind testing
The prevalence rate in the sample population is consistent with the target population
index
authenticity
gold standard Screening patients non-patients -
Sensitivity
actual illness
Screen positive
find patient
False negative rate (missed diagnosis)
suffer from
Negative
Missed diagnosis
Specificity
Actually disease-free
Screen negative
exclude patients
False positive rate (misdiagnosis)
none
Positive
Misdiagnosis
Correct index (Youden index)
Lingte➕1
Total ability to identify true patients from non-patients
likelihood ratio
positive likelihood ratio
True Yang/False Yang
negative likelihood ratio
False vagina/true vagina
reliability
Reliability (reliability/precision/repeatability·), under the same conditions - a certain measurement tool, repeated measurements of the same subject - degree of consistency
Continuity measurement data
Same batch of samples - multiple times, standard deviation/coefficient of variation
Different samples - two repeated measurements, correlation coefficient r>90%
Paired t test, there is no statistical difference between the two groups
Classified measurement data
Compliance rate (consistency rate)
Kappa value
>=0.75 Excellent consistency <=0.4 Poor consistency
Factors affecting reliability
Subject biological variation
observer
laboratory conditions
You are different, I am different, the tools are different
Predictive value
Applying Screening Results /-Estimated Patients/Non-Patients
positive predictive value
Proportion of people who screen positive who have the target disease
negative predictive value
Yin - no suffering
The relationship between predictive value, authenticity index and prevalence rate
Current prevalence ⬇️- Yang ⬇️, Yin ⬆️
Sensitivity ⬆️ - Yang ⬇️, Yin ⬆️
Positive cutoff values for continuous measures
Yang/Yin boundary value - normality/abnormality of a certain indicator
Distribution of measured values
independent twin peaks
In principle - patient minimum Typically 99-99.9% CI upper limit for non-patient testing
partially overlapping double peaks
Poor prognosis, serious missed diagnosis-⬆️Sensitivity
Follow-up treatment method ❌-⬆️Specificity
unimodal continuous
Turning Point - Avoid Missed Diagnosis
ROC curve and application
Patient/Non-Patient Measurements - Smallest to Largest - Cutoff, Sensitivity/Specificity
Abscissa: 1-specificity Vertical coordinate:; sensitivity
Upper left corner of coordinate axis - optimal cutoff value
and x-axis area-AUC-1; 0.5 has no application value
Evaluation of screening effectiveness
Evaluation stages and research methods
Phase 1 (field intervention study)
randomized controlled trial
Intervention: Continuous Periodic Screening Comparison: routine medical services
The second phase (screening demonstration area construction phase)
Multicenter community-based trial
The third stage (verification and application stage)
Observational studies - long-term biological effects, health economics evaluation, sustainability
Screening Program Benefits
Benefit, after screening - patients who were not found originally - get treatment and diagnosis
Common indicators
positive predictive value
Referral rate/screening positivity rate
Early diagnosis and treatment rate
Improvement methods
Strategies for high-risk groups
Choosing the right screening test
Early diagnosis is of great significance - no missed diagnosis, high sensitivity
joint experiments
series connection
series of tests
A set of tests - a certain sequence, preliminary screening, next round, all yang is yang
⬆️Specificity
in parallel
Parallel test
All - all carried out at the same time, any one is positive
⬆️Sensitivity
Starting age and time interval for screening
Biological effect evaluation
Outcome Measures
Attributable mortality, cure rate, case fatality rate, survival rate
Related indicators
Randomized controlled trials - effectiveness index, attributable risk, protection rate
Observational study-RR\OR
Number of people to be screened
health economics evaluation
Screening cost, cost-effectiveness, -utility (subjective perception of effect), -benefit, health economics model
Safety, Ethical Issues and Sustainability Assessment
common bias
lead time bias
The time point of screening diagnosis - the time point of routine clinical diagnosis (natural course of disease), the disease is discovered earlier/❌The time point of death of the screened population
course bias
Possibility of being detected - speed of progression; large proportion of slow - overestimation of screening effect
volunteer bias
Health Behavior-Willingness to Screen Participants - Education, Finance, Bad Habits, Compliance
overdiagnosis bias
Too many early cases - burden of diagnosis and treatment, indolent cases
array research
Overview
concept
Select research object-? /Exposure level Grouping-Follow-up observation-Examination registration Outcome occurrence-Comparison-Evaluation and inspection E D
exposed
Exposure to a substance to be studied
have certain characteristics or behavior
queue
people within a specific range
birth cohort, exposure cohort
fixed queue
dynamic queue
risk factors
Cause disease or increase its probability
Features
Observation
Set up controls
cause and effect
Exposures identified before disease occurs
Strong ability to test causal links between exposure outcomes
use
Testing hypotheses about etiology
Evaluate the effectiveness of preventive measures
Post-marketing surveillance of new drugs
natural history of disease
Reviewing new history
type
Forward-looking
Grouping-current exposure situation, the outcome has not yet appeared, and prospective observation is required
E D first-hand information-little bias
Large sample, observation time, cost
historic
Grouping - Already mastered Exposure situation at a certain point in the past Historical data, already present, not needed
Collection and analysis - short period, from cause to effect, saving
Content, complete and reliable historical information
bidirectionality
Selection principles
Forward-looking
Higher morbidity and mortality
Explicit testing hypothesis
outcome variable
Clearly defined measurement of exposure factors
Enough to observe the crowd
E;NE
Most can be followed up to the end
Sufficient human, material and financial resources
historic
1-5
Sufficiently complete and reliable historical information
Research design and implementation
Identify research factors
Quantification of exposure
Level, time—cumulative dose
Exposure method
continuous/intermittent
direct/indirect
One time/long term
Measurement methods
Sensitive, precise, simple and reliable
Other relevant factors
Confounding factors, demographics
Determine study outcomes
Expected outcome event—the natural end point of an observation
Comprehensive, specific and objective/outcome measurement - unified standards and strict compliance
Research object
Observation end time
The length of the observation period (latency period, person-years)
entire research work
Research site and research population
research site
A sufficient number of eligible research subjects
Attention from leaders and support from the masses
cultural and educational level, medical and health conditions, transportation
Good representativeness
Research object
Exposed people
general population
All people in a certain area
professional group
Specially exposed groups
organized group of people
Effective data collection and comparability
control population
internal control
External control
total population vs.
The proportion of the entire population and those exposed is very small
multiple controls
Determine sample size
Population incidence, significance level, test power, difference between exposure and control population incidence
Data collection and follow-up
Follow-up objects
Same method, same follow-up
Lost to follow-up - analysis of reasons for follow-up/loss to follow-up
Baseline data of those who were lost to follow-up and those who continued to observe - deviation
Follow-up method
Face-to-face interviews, telephone interviews, self-completed questionnaires, regular physical examinations, monitoring, and recording
Follow-up content
Baseline data, outcome variables
QC
Compilation and analysis of data
Cases Non-cases Exposome control group
Number of cases Person-hours Exposome control group
Calculation of person hours
Number of observers*observation time
Average population observed in each year (average population at the beginning of two consecutive years)
life table
Inclusion into the cohort, loss to follow-up, and endpoint outcome in that year - 1/2 person-years
Commonly used indicators for calculating rates
cumulative incidence
Large quantity and relatively stable CI=Number of cases during the observation period/Number of people at the beginning of the observation
Risk of disease within a specific period of time
Magnitude change: 0-1
The length of accumulated time must be stated
Incidence density
The population is unstable, the follow-up time is long, and there are losses to follow-up. ID=number of cases during the observation period/total number of observation hours
Rate (instantaneous frequency)
0-∞
Description unit
Standardized ratio
Small number of study subjects, lower incidence of outcomes
Incidence rate of the whole population——>Theoretical number of patients; actual/theoretical
Standardized proportional death ratio
The population data of a certain unit over the years cannot be obtained.
(Number of deaths from a certain disease in the entire population/Number of total deaths) * Actual number of total deaths per unit
Effect estimate index
Relative risk RR
risk ratio
Ratio
How many times the risk of morbidity or death in the exposed group was that of the control group Exposure-disease association
Etiological significance
Attributable risk AR
Specific risk, poor risk, excess risk
Risk is specifically attributable to the E level and exposure is eliminated, reducing the incidence of disease by x%
public health significance
Attributable risk percentage AR%
Etiology score EF
Morbidity or death in exposed population Attributable to E/All Morbidity or death
Population attributable risk PAR
Total population incidence rate attributable to E
Population attributable risk percentage PAR%
PAR accounts for the percentage of total morbidity (death) in the total population
bias
selection bias
refuse to participate
Improve response rates and compliance
Data lost
The file information of the target group is complete and the missing/incomplete information is within certain limits.
volunteer bias
Comparison of the basic situation with the normally selected population
Misclassification bias (early patients not detected at study start)
Select research subjects according to prescribed criteria
Correct sampling methods and randomization principles
attrition bias
Study subjects dropped out of the cohort due to various reasons (migration, emigration, death from non-endpoint diseases, refusal to participate)
Query whether there is death and the cause - mortality rate - morbidity rate
Baseline Characteristics - Likelihood of Different Diseases
information bias
Specific—RR high/low; nonspecific—1
Measurement methods, calibration instruments, and strict experimental operating procedures
Equal treatment, diagnostic technology, clear standards, strict compliance with regulations
training
confounding bias
Influencing factors, research factors-uneven distribution
Study design stage; restrictions (age group, gender), control matching
data analysis stage
Stratification, standardization, multi-factor
Advantages and Disadvantages
advantage
Collected before the outcome occurs and observed by the researcher in person - complete and reliable, free of information bias
Incidence rate, directly calculate RR, AR
Before cause, after disease - time sequence, test causal ability
Natural history, multiple diseases from one cause
shortcoming
Not suitable for very low incidence
Long follow-up time, compliance-loss to follow-up bias
The introduction of unknown variables and changes in known variables - affecting the outcome and complicating the analysis
A waste of manpower, material, financial and time
Other practice types
Study based on a comprehensive cohort
Not based on a certain exposure factor at the beginning - meet certain conditions within a certain range, collect exposure information of suspicious factors, check health status - prospective observation, and then group analysis after the end of the study
No clear research factors at the beginning of the study, grouping/collecting a large number of questionable factors
forward-looking
When analyzing interest - a research factor
Comprehensive etiology research (unknown cause)
Multiple diseases due to multiple causes, improve research efficiency
Based on big data
The basic idea
Research question - Find the exposure group and control group in big data - Check the outcome information = Analysis E D
Features
historical cohort study
Convenient and fast
Overcome limitations of people, materials, finances and time
case control
Overview
Fundamental
Grouping - Ask about laboratory tests, review medical history Collect past exposure history - Measure and compare whether the difference in exposure proportion between the two groups is statistically significant - Assess bias -? Risk factors - exploring and testing causative hypotheses
feature
observational study
Grouping - whether there is an outcome of the study
trace the cause from the effect
The strength of the argument for causal link is relatively weak
use
Factors influencing health-related events
Causes/Risk Factors
Factors influencing clinical efficacy
disease prognostic factors
Chronologically
type
non-matching (grouped)
From the specified case-control population - a certain number of people are selected separately and compared between groups - there are no restrictions/regulations on the selection of controls.
match
Certain factors/characteristics of controls Case agreement - matching factors Equilibrium - exclusion
derivative
nested case-control
On the basis of a cohort study - within a certain observation period
Accumulation of new cases - all concentrated - case group
The time of onset of each case Non-affected persons in the same cohort - matched, randomly selected controls - control group
Extract baseline data and test biological specimens
Matched case-control statistical analysis
Features
Individual matching, temporal relationship (recall bias), same cohort-comparability (selection bias)
Different control groups for different diseases
case cohort
Cohort study at the beginning Randomly select a representative sample according to a certain proportion - the control group
Observation ends All cases - case group
Compare
Controls were included from baseline
Common to multiple diseases
case-case
Two subtypes of a disease, direct comparison without separate controls
Study the differences in causes between the two groups
Identical or similar risk factors - masked or underestimated
Interaction of genetics and environment
Case crossover
One or more time periods before the onset of each case - control Exposure at the time of disease; comparison
Transient effects of exposure factors, acute events
Research design and implementation
Determine research purpose
Identify the type of research
Extensive exploration of risk factors - non-matching, frequency matching
Testing for etiology/small samples – individual matching
Research object
cases
definition
Unified and clear diagnostic criteria, gold standard - convenient for comparison
Not yet - self-defined standards, balanced false -
Special research purposes - regulations or restrictions
type
new cases
Good representativeness, relatively accurate and reliable recall information, and easy access to case data
Difficult to obtain expected number of cases
Current cases
A sufficient number of cases can be obtained in a shorter period of time or in a smaller range
Poor recall reliability and difficulty distinguishing chronological order
Deaths
Poor accuracy
Diseases that mainly rely on information provided by relatives and friends (leukemia)
source
Hospital
Poor representation (choose different levels of categories)
Cost-saving, good cooperation, easy to obtain information, complete and accurate
Community
Good representation - suitable for extrapolation
Investigations are difficult and time-consuming
control
Selection principle
Same diagnostic criteria, representative case source population - consistent exposure distribution among case source population
source
Other cases diagnosed by the same or multiple medical institutions
❌Diseases known to be associated with the exposure studied
Multiple diseases
Non-cases or healthy people in the community or group population
❌Selection bias/implementation difficulty and cost
neighbor or same residential area
socioeconomic status
Spouse, compatriot, relative, classmate, colleague
environment or genetics
match
Certain characteristics or factors are consistent and comparable with cases - eliminating interference
Improve research efficiency and control the interference of confounding factors
Precautions
Known confounders/well-founded suspicion
Intermediate variables in the causal chain ❌
It is only related to suspicious factors and has nothing to do with the disease❌
Research variables of interest to the researcher❌
Overmatching
Not confounding factors but possible risk factors for matching
Classification
frequency matching
Control group - the proportion of people with certain factors/characteristics - consistent with the case group
individual matching
pair
Sufficient sources - highest statistical efficiency
1:r match
Rare disease/few qualified cases obtained
Sample content
Exposure rate, significance level, test power, correlation strength OR of the research factors in the control group/population
research factors
Data collection method
Data compilation and analysis
Analysis steps
Descriptive statistics
General characteristics
Balance test
inferential analysis
Is there any connection?
Association strength
OR - the ratio of disease to exposure ratio
Ratio/Ratio - the probability of something happening/the probability of not happening
How many times more dangerous is the disease in exposed people than in non-exposed people?
>1, risk factors
<1, protective factor
=1, no statistical correlation
non-matching design
Exposure history Cases Non-cases have none
Stratified analysis
Presence or extent of potential confounders - stratification
Calculate OR for each layer - no statistical difference, homogeneous Interactions between heterogeneous-stratification factors and exposure factors
The ORi of both layers is larger than that of the non-layered one - confounding effect
Matching design
cases Control with exposure without exposure exposed no exposure
bias
selection bias
Admission rate/Berkson bias
hospital based
Patient - a specific case in this hospital - ❌ a random sample of all patients
Control - a certain group of patients - ❌ the entire target population
control
Communities, hospitals of different levels/types, Control - multiple departments and diseases in multiple hospitals that are the same as the cases
Current case-new case bias /Neyman
Current cases - longer disease course - exposure information, survival/❌ onset
Survivors - due to disease, changes in original exposure characteristics - mistaken for pre-disease
control
new cases
Detecting symptoms/exposure bias
Certain factors - ❌Cause - having certain symptoms or signs - seeking medical attention - increasing the detection rate of early cases of the disease - overestimating the exposure of the case group
control
Early, middle and late stage patients from different sources
information bias
recall bias
Research object
Exposure/Past History - Accuracy and Completeness of Recall
control
Utilize objective recording information, questioning methods, and investigative techniques
new cases
survey bias
Investigator/Investigation Environment
Inquiry methods, measurement methods, instruments or reagents
control
Training, unification - questioning methods, survey techniques, objective indicators
⬇️Survey bias
gain trust
⬇️Reporting bias
Instrument calibration
⬇️Measurement bias
confounding bias
Advantages and Disadvantages
excellent
Suitable for rare diseases and long incubation period diseases-cause research
Save people, money and time, easier to organize and implement
Multiple exposures, disease - exploratory etiology analysis
Wide range of applications - discussion of causes, analysis of causes of other health events
lack
Not applicable to factors with low exposure proportion in the population
Selection/recall bias is difficult to avoid
Difficult to judge time sequence - weak ability to demonstrate cause and effect
❌Incidence rate, RR
experimental epidemiology
Overview
definition
Researchers - Research purposes - According to the pre-established research plan - Research objects, random allocation (experimental group, control group) - Artificially imposed/reduced treatment factors - Follow-up observation - Comparative analysis - Effect of treatment factors
feature
Forward-looking
to intervene
Group
From a population Meet the inclusion and exclusion criteria Signed informed consent - Random assignment - Comparable
use
Testing hypotheses about causation
Evaluate the effectiveness of disease prevention and treatment
prevention
Vaccines, dietary adjustments, appropriate exercise, smoking cessation and limiting alcohol consumption
treat
Single/combination medication, surgery, treatment options
type
Clinical Trials
Individual patients - Trial grouping/application of intervention Hospitalization/non-hospitalization - the effect of a certain drug or treatment method
Research object Individual patient, consistent baseline
research site Hospital
Research purposes Therapeutic
Randomly assigned Randomly assign treatment measures and conceal the plan
noncompliance Measurement extent and reasons
Use blinding whenever possible
Field trials (population prevention trials)
People who are not yet sick - individuals/❌subpopulations - Prevention of very common and serious diseases
Non-patient individuals, more
Community School factory
preventive
Randomly assign measures on an individual basis
Measurement extent and reasons
Use blinding whenever possible
Community Trial (Community Intervention Project CIP)
Population as a whole (community, subpopulation) - Some preventive measures or methods for assessment or evaluation
community crowd/ certain population/subgroup
Community
Assessment/evaluation
Cluster random allocation, comparable between groups
Research design and implementation
Define the research question
P (diagnostic criteria, age and gender, disease course, past history, treatment history) I (intensity, frequency, approach) C O (measurement method, time)
Determine the test site
people
The population is relatively stable, mobility is small, and the population is sufficient
sick
A high and stable incidence rate
Vaccine effect-no recent illness
land
medical and health conditions
Leaders pay attention and the masses are willing
Research object
Effective (vaccine-susceptible groups)
High incidence (vaccine-areas with high incidence of disease)
Intervention does no harm to it
can persist to the end
Good compliance
Sample content
Significance level, test power, numerical difference between two groups of outcome indicators, one- and two-sided tests, number of groups
Randomization and group concealment
randomization method
simple random grouping
Individual - Coin toss, lottery, random number table
block randomization
Similar conditions - a block, pure random allocation to group the research subjects within the block
stratified randomization
According to mixed stratification, simple random grouping within each stratum
Cluster randomization
Communities/Groups - note comparability
group hiding
Prevent investigators/patients from recruiting patients - knowing the randomization plan before grouping - preventing the randomization plan from being unhidden in advance
in principle
Assignment of random numbers - once a patient is confirmed to be included
Distribution plan-hidden
Random number assignment for a patient - done once and cannot be changed
Group time - close to treatment start time
Set up controls
type
Control measures
Standard therapy vs.
Best current or conventional therapy
placebo control
There is no effective treatment drug/the use of placebo does not affect the condition
single/cross
parallel control
cross control
AB-BA
other
self control
before and after test
Historical comparison
Blank control
necessity
unpredictable ending
Individual biological differences - inconsistent natural history, treatment response
regression to the mean
Extreme clinical symptoms or features
Hawthorne effect
Know that you are receiving special attention - change your behavior or status
placebo effect
Dependence on medicine-positive psychological effects
potential unknowns
Application of blinding
Classification
single blind
Research object
double blind
➕Research implementation staff
triple blind
➕Data collection and analysis personnel
four levels
Assign patients
patient himself
physician caring for patients
Research Conductor-Evaluation Results
Identify outcome variables and how to measure them
Main outcome measures
secondary outcome measures
Determine the trial observation period
gather information
Data analysis and organization
exclude or opt out
exclude
Pre-randomization - ❌ Internal truth/impact extrapolation
reason
Those with taboos, those who cannot be traced, those who may be lost, and those who refuse to participate
quit
After randomization - insufficient sample size, study power, selection bias
reason
Unqualified
Did not meet inclusion criteria and was not accepted once
noncompliance
Lost to follow-up
Intention-to-treat analysis
Select case | Randomly assigned /\ A B B A B A 1⃣️2⃣️3⃣️4⃣️
ITT intention-to-treat analysis
1⃣️ 2⃣️/3⃣️ 4⃣️
All patients randomized - complete experiment? /Really get treatment? -Stay in the original group for analysis
Therapeutic effects after actual clinical application
underestimate
Efficacy analysis (adherer analysis)
2⃣️/3⃣️
overestimate
receive treatment analysis
1⃣️ 3⃣️/2⃣️ 4⃣️
overestimate
effectiveness and effectiveness
Effectiveness - ideally - true acceptance and completion
Effect - clinical status - actual effect
Evaluation index
Effect of treatment measures
Effective rate, cure rate, N-year survival rate
Effectiveness of preventive measures
Protection rate = (pair-real)/pair
Effect index = true/real
Number of people needing treatment
1/(True-True)
To prevent one adverse event, the number of patients who need to be treated using a certain therapy within a period of time
Advantages and Disadvantages
excellent
Research purpose, experimental plan - (research objects, intervention factors, result analysis) - standardization
Randomization - comparability, confounding bias
Forward-looking - able to draw firm conclusions
lack
Design/implementation requirements are high, control is strict, and difficulty is high
Constraints on the scope of application of intervention measures - insufficient representation, extrapolation of effects
The study population is large and the follow-up time is long - compliance is not easy to achieve
Issues that should be noted
class test
Natural experiment, complete (randomized controlled intervention prospective) - missing one/several features
Whether to set up a comparison
No parallel comparison
self before and after, and known results
Set up a control, but the groups are not randomized
ethical issues
Animal experiments first, no harm to the health of subjects, informed consent
pilot test
The scientificity and feasibility of small-scale, experimental design - ❌ blind waste
Study registration issues
Full transparency in results reporting
Comparison with cohort studies
same
Prospective—testing hypotheses about etiology
In addition to research factors, other factors are comparable
Consistent timing, from cause to effect
different
❌Randomly assigned, exposed or not
Random allocation (experimental group, control group)
Observing the occurrence of E/NE diseases in the natural state
intervening factors
Factors affecting research results are more complex
Under artificial control conditions - stronger verification ability
Clinical trials for new drug discovery and development
I
Tolerability, pharmacokinetics
20-80
II
Controlled, randomized and blinded safety, effectiveness
200
III
Randomized multicenter
hundreds/thousands
IV
Post-market surveillance
prevention strategies
health definition
physical, mental, social; not just the absence of disease or infirmity
factors affecting health
individual
genetic and biological factors
lifestyle factors
socioeconomic status
Income, education, occupation
environment
natural environment
built environment
social and economic environment
Social support network, social culture, policy
health services
medical model
biomedical model
Health is the absence of disease
Effect of biological factors/biological dysfunction of the body
Medical measures (drugs, surgery) - recovery
biopsychosocial medical model
Four levels: physical, psychological, spiritual and social - multi-factor synthesis
Prevention, management, rehabilitation, health promotion
Prevention Strategies and Measures
Strategy
Guiding ideas and action plans formulated to achieve a certain goal, strategic and overall
measure
Specific methods and steps taken to achieve the expected goals, tactical, local
disease prevention
Related concepts
prevent disease
Prevent the occurrence and delay the development of disease and disability
wipe out
Stop all diseases
eliminate
reduced to a very low level
natural history of disease
Susceptible phase, subclinical phase, clinical phase, recovery phase
Tertiary prevention
Level 1
Cause Prevention Not yet happening - Causes/Risk Factors
fundamental measures
Level 2
Three early preventions: early stage of disease - symptoms and signs have not yet appeared
Level three
Clinical prevention/disease management Obvious manifestations of symptoms and signs-symptoms/recovery
High-risk group strategies and population-wide strategies
definition
Clinical thinking, high risk of disease-risk factors, measures to be taken-⬇️exposure level/risk of disease
Public health thinking, ⬇️exposure level of the entire population/total population burden
advantage
Proximal link of the cause - highly operable/cost-effective
The cause is remote environment/covers a wide population/the total benefits of the population are considerable/the risk curve of the entire population shifts towards the low-risk direction
shortcoming
High-risk groups - psychological stress/a small number of people who behave differently - limiting effects/compliance
Insufficient individual benefits/difficult to be understood and accepted
health protection and health promotion
health protection
Health protection, targeted measures - protect individuals/populations ❌ Hazardous substances - health damage
Eliminate/control harmful factors, protect barriers, enhance resistance/take measures after exposure
health education
Information dissemination and behavioral intervention, mastering health care knowledge and establishing health concepts
Get information, raise awareness - voluntarily adopt beneficial health behaviors and lifestyles
health management
Individual/Population Risk Factors - Comprehensive Regulation
Doctors provide individual guidance - chronic non-communicable diseases
health promotion
⬆️People’s ability to control factors affecting health/improve their own health
Covers three strategies Prevention based on medical intervention measures health education Health protection based on legislative, economic or social measures
infectious disease epidemiology
Basic concepts of infectious diseases
caused by pathogens
Diseases that can be spread from person to person, animal to animal, and person to animal
infection process
Definition of infectious process
Pathogens enter the host and interact with the host and fight against each other.
individual phenomenon
Infectious diseases develop and end
Pathogen
Various microorganisms that cause disease in the host
microorganism
Viruses Bacteria Rickettsia Mycoplasma Spirochaete
Parasite
characteristic
Infectiousness
ability to cause infection
Second generation incidence
Pathogenicity
ability to cause disease
Infection rate; proportion of people who develop clinical symptoms
Virulence
cause severe disease
Case fatality rate/severe cases
Antigenicity/Immunogenicity
produce specific immunity
Antibody positive conversion rate
Pathogen mutation
Antigenic variation
Gene mutation - changes in antigenicity - the specific immunity originally acquired loses its effect
Virulence variation
Environmental Factors Host Factors - Boosting/Attenuating (Vaccine Preparation)
drug resistance variants
Drug sensitivity-insensitivity/resistant
Resistance genes/gene mutations – passed on to future generations
Viability outside the host
impact on the spread of infectious diseases
Most are weak-strong (spores, hepatitis B virus)
Host
People/animals that can be parasitized by infectious pathogens under natural conditions
defense mechanism
skin mucosal barrier
internal barrier
Phagocytosis
normal body fluid barrier
specific immune response
Humoral immunity
cellular immunity
Infection spectrum/infection gradient
The severity of the host's infection process with the pathogen
Classification
Mainly latent infection
Polio, meningitis, Japanese encephalitis
Must be monitored by laboratory
Overt infection
chickenpox measles
Mainly death
Rabies
popular process
popular process definition
Pathogens are discharged from the source of infection and invade susceptible people through a certain transmission route to form new infections.
Basic links
Source of infection
People or animals that have pathogens growing and multiplying in their bodies and capable of expelling them
Classification
patient
pathogen carrier
People who are asymptomatic but able to excrete pathogens are carriers of bacteria, viruses, and parasites
Classification
incubation period
carried during the incubation period and excreted from the body
Measles, dysentery
recovery period
Temporary
Symptoms disappear within 3 months
Chronic
more than 3 months
healthy pathogen carriers
Never had it but can pass it, the amount passed is small
Hepatitis B, meningitis
infected animals
Zoonotic diseases: vertebrates/humans, naturally transmitted
Classification
Mainly animals
Transmitted between animals, can be transmitted to humans, but not transmitted between humans
Rabies, forest encephalitis, leptospira
People-oriented
Transmitted among humans and occasionally infected animals
Human tuberculosis, amoebic dysentery
Pay equal attention to humans and animals
mutual source of infection
Schistosomiasis
true zoonosis
Using humans and animals as final hosts and intermediate hosts respectively
Taeniasis
way for spreading
basic concept
way for spreading
The whole process experienced after excretion, before invading new susceptible hosts, and in the external environment
Horizontal communication - with the help of communication factors, between people Vertical transmission - mother, direct to offspring
vehicle
propagation factors
Inanimate matter (water air food soil)
media
Living organisms (insect vectors)
Classification
Air
Classification
Droplets
less resistant
droplet nuclei
Resistant to drying
dust
Strong resistance
popular features
The transmission route is easy to realize, spread widely, and the incidence rate is high
Seasonal-winter and spring
People without immune prophylaxis-cyclical
Overcrowding and high population density
water
drinking water
Water supply scope, drinking water source history
There is no difference in age, gender or occupation in the onset of disease
Frequent pollution, cases continue all year round
Take disinfection and purification measures and the outbreak can be quelled
plague water
History of exposure to infectious water
Regional seasonal and occupational distribution
A large number of susceptible people enter the epidemic area and an epidemic breaks out
Strengthening protection and taking effective measures against epidemic water
food
People with a history of eating the same food and not eating the same food will not develop the disease
The incubation period is short and a large amount of contamination can lead to an outbreak; multiple contaminations last for a long time.
Stopping food can calm down
soil
Intestinal parasitic diseases, spore-forming bacterial diseases
Survival time in soil, contact opportunities between humans and soil, personal hygiene habits and working conditions
arthropods
Classification
Mechanical carry
Not developing in the body, contact with regurgitated and feces
biology communication
blood sucking bites
epidemiological significance
Regional
Seasonal
Occupational distribution characteristics
age difference
touch
Classification
direct contact
indirect contact
Items contaminated with pathogens
epidemiological significance
Most cases are sporadic, and clusters of cases may occur within families or people living together.
Poor sanitary conditions and poor hygiene habits
Iatrogenic
contaminated equipment
Contaminated blood transfusions, medicines or biological agents
vertical
placenta
Upward
during childbirth
Susceptible groups
Related definitions
population susceptibility
The susceptibility of a population as a whole to infectious diseases
population immunity
Population resistance to pathogen invasion and spread
Proportion of immune population in the population
Influencing factors
rise
Increase in newborns
immigration
Decrease in immune population
Emergence of new pathogens or mutation of pathogens
reduce
Vaccination
Infectious disease epidemic
Epidemiological significance of infectious diseases in various stages
Infectious period
The entire period during which the patient sheds pathogens
epidemiological significance
Short—occurs in clusters
Long-term cases continue to appear one after another
Patient isolation period
It takes a certain amount of time after infection to become contagious
incubation period
Invasion of the body - the earliest clinical symptoms or signs appear
significance
Epidemic characteristics affecting the disease
short-burst
Long - lasts a long time
Determine when the patient was infected - source of infection and route of transmission
Contact quarantine and medical observation period
Determine the timing of immunizations
Evaluate the effectiveness of control measures
clinical symptom stage
Specific clinical symptoms and signs occur
A large number of pathogens reproduce, symptoms that are conducive to the elimination of pathogens, and the most contagious
recovery period
Symptoms disappear and body gradually recovers
Begins to develop immunity and eliminate pathogens from the body; generally not contagious, some patients can still shed pathogens during the recovery period (hepatitis B), and some can shed pathogens for a long time (typhoid fever)
foci
The spread of an infectious source and the pathogens it discharges to the surrounding area, the basic unit of the epidemic process
forming conditions
Conditions under which infectious agents and pathogens can continue to spread
The size of the foci
Existence time and activity scope of the infectious agent
Characteristics of transmission routes
Immunity status of surrounding people
elimination conditions
The source of infection is removed or no longer discharged
Eliminate pathogens released into the external environment
There are no new cases or new infections among all surrounding susceptible contacts during the longest incubation period
relationship to the popular process
The epidemic process depends on the overall effect of the interaction of the three links-benefit and continuation
A series of interconnected and successive epidemic foci constitute the epidemic process of infectious diseases.
Each foci, previous, new base
Basic unit - destroyed, end of epidemic process
Factors affecting the epidemic process
natural factors
climate soil and geography
social factors
more important
Production and living conditions, medical and health conditions, lifestyle and religious beliefs
Prevention Strategies and Measures
Infectious Disease Prevention Strategies
prevention-oriented approach
Population-wide/high-risk group strategies
measure
Infectious Disease Surveillance
Notifiable infectious diseases (40 types)
A2, B27, C11 types
Monitor content
Demographic information
population immunity level
two people
Morbidity and mortality and their distribution
Pathogens - categories, virulence, resistance variants
Two diseases
Animal hosts Insect vectors—population distribution, pathogen carriage
Transmission dynamics and influencing factors
Two spreads
Evaluation of the effectiveness of preventive measures
Epidemic prediction
Special investigation (outbreak, underreporting investigation)
Reporting time limit
Class A Class B A pipe
2 hours
other
24 hours
Eliminate sources of infection
patient
Early detection, early diagnosis, early reporting, early isolation and early treatment
early in the morning
pathogen carrier
Isolation treatment
Class A Class B A pipe
Occupational and behavioral restrictions
Typhoid fever and hepatitis B that cannot be cured for a long time❌Food industry
Blood donation is strictly prohibited for HIV/AIDS and Hepatitis B
Susceptible contacts
Check, observe, and take necessary precautions
infected animals
Degree of harm Economic value
Isolation and treatment, killing, burning, landfilling
Cut off transmission routes
disinfect
preventive
No clear source of infection found
foci
at any time
The source of infection is still at the foci
end
The infectious agent is cured and dies or leaves
Insecticide
Protect vulnerable groups
personal protection
Vaccination
initiative
passive
drug prevention
Solutions to infectious disease outbreaks
Report to health department
Government organizations cut off transmission according to plans
emergency procedures
Limit or stop gatherings of people
Suspension of work, suspension of business and classes
Temporary requisition of housing, transportation and related facilities and equipment
Contain contaminated items
Close places where infectious diseases may spread
Contain or cull infected animals
Stop, use, block, kill
Conduct an investigation
On-site treatment
publish information
Vaccination and Immunization Program
Vaccination
type
artificial autoimmune
Antigens (vaccines, toxoids)
artificial passive immunity
Antibodies (immune serum, immunoglobulin)
artificial passive autoimmunity
Precautions
Contraindications
Abnormal reaction
Adverse reactions
Vaccine quality accident
Vaccination accident
Coincidence syndrome
psychogenic reaction
Immunization Program
National infectious disease prevention and control plan, selecting vaccination plans according to regions, vaccinating susceptible groups, improving immunity, and preventing diseases
Evaluation
Immunological effects
Antibody positive conversion rate
epidemiological effects
protection rate
effectiveness index
Immunization program management evaluation
chronic disease epidemiology
definition
The cause of the disease is complex, the onset is insidious, the course of the disease is long, and the condition is protracted.
major risk factors
Unchangeable
genetics, gender, age
Can be changed
four behaviors
smoking
excessive drinking
Unreasonable dietary habits
Less physical activity
Two exposed
Occupational and environmental exposure
infectious pathogens
Sanhua
Aging population
rapid urbanization
The globalization of unhealthy lifestyles
prevention strategies
Emphasis on fundamental prevention among tertiary prevention
Population level: Preventing the prevalence of risk factors
Individual: Don’t have risk factors in the first place
life course strategies
Beginning early in life and continuing throughout life
High-risk strategies for the entire population
System engineering led by the government, coordinated by multiple departments, and participated by the whole society
Precaution
primary prevention
Cause prevention, targeting the causes or risk factors before the disease occurs
Obesity control, dietary balance, smoking cessation and alcohol restriction, health education
secondary prevention
Three early prevention measures: early symptoms of the disease have not yet appeared or are difficult to detect
Screening of high-risk groups
Tertiary prevention
Clinical prevention or disease management, symptoms and signs are obvious
Symptomatic treatment and rehabilitation
public health surveillance
Basic concepts and characteristics of public health surveillance
long-term, continuously and systematically
gather information
scientific analysis and explanation
Timely feedback and rational use
Guide the formulation, improvement, and evaluation of public health interventions and strategies
Related concepts and terms
passive monitoring
Subordinates -> superiors report, superiors passively accept
Notifiable Disease Reporting Information System
Public health emergency reporting system
Spontaneous reporting system for adverse drug reaction monitoring
Active monitoring
Superiors specially organize investigations and collect information
Immunization coverage monitoring
Investigation on underreporting of infectious diseases
Monitoring activities for certain key diseases or behavioral factors
General reports
stipulated by the health administrative department
Notifiable infectious diseases
sentinel surveillance
Popular characteristics Representative groups or regions
AIDS
Purpose
Describe the distribution characteristics and changing trends of health-related events
Evaluate the effectiveness of public health intervention strategies and measures
application
Case intervention—preventing infectious diseases/reducing morbidity and mortality
Evaluate impact and determine change trends
Properly allocate health resources
Intervention effect
Analyze high-risk groups
Analyze disease
Cause, spread, risk factors for progression
type
disease surveillance
infectious disease
Statutory 40 (Class A 2, Class B 27, Class C 11)
Chronic non-communicable diseases
Hospital Infection
Cause of death monitoring
Symptom monitoring
New diseases (the cause is unknown and there is no clear clinical diagnosis method)
Behavior and risk factors
other
Environment, food hygiene, nutrition, school hygiene, adverse drug reactions
Way
"land"
Hospital
Notifiable infectious diseases, adverse drug reactions
laboratory
influenza
"people"
crowd
behavioral risk factors
Case
Public health emergencies, food safety incidents
"thing"
Metrics (quantitative data)
Notifiable infectious diseases, symptoms, behavioral risk factors
event
public health emergency
Methods and techniques
Case registration
Unassociated anonymous monitoring
Record connection
Collect monitoring information online
Online direct reporting system
Automatic early warning technology
geographic information system
Mnemonic: "Waiting for you" to connect to the alarm location
Quality evaluation of monitoring systems
integrity
sensitivity
specificity
Do it in time
representative
simplicity
flexibility
Epidemiology of public health emergencies
Overview
Emergencies
Sudden occurrence, causing or may cause serious social harm, emergency response measures - natural disasters, accidents, public health incidents, social security incidents
public health emergency
Sudden occurrence, causing or may cause serious damage to public health
major infectious diseases
mass unexplained disease
Major food and occupational poisoning
other
define
Scope to one community or more
A large number of casualties may endanger life safety and property loss.
Failure to take effective measures - the situation escalates
Government coordinates multi-sector participation
Mobilize the masses and initiate emergency measures or plans
feature
Sudden
The difficulty of prevention and preparation
Diversity in performance
Complexity of Disposition and Ending
group nature
Many performances, many endings, many people
seriousness of consequences
public health problems caused by
Ecological damage, food pollution, water pollution, vector breeding, epidemic of infectious diseases
installment
incubation period
Develop plans and establish various preventive strategies and measures
Early warning system, emergency processing system
outbreak period
Quick response
processing period
Isolation, blockade of epidemic areas, disinfection, vaccination, personal protection
Investigate the cause
recovery period
Grading
Level I: extremely serious
Pneumonic plague, pulmonary anthrax
SARS, human infection with highly pathogenic avian influenza
New infectious diseases and introductions that have not yet been discovered in my country
Infectious diseases occur in the surrounding areas and are imported
Particularly serious food safety incidents in more than two provinces
Cross-regional and cross-border food safety incidents
A cluster of unexplained diseases involving multiple provinces
Loss of strains, strains, and pathogenic factors of severe diseases
other
Level II: Major
Level III: Larger
Level IV: General
Risk assessment of public health emergencies
content
Type and nature of event
Development trend analysis
Impact scope and severity
Evaluation of the effectiveness of prevention and control measures
Incident grading and initiating response
evaluation process
Risk Identification:
Risk identification must be regularly implemented throughout the entire process of public health security implementation.
Risk analysis: The process of quantitatively analyzing the probability and extent of loss.
Risk assessment: Determining the severity of risks and making decisions
Epidemiological Investigation
The significance of conducting epidemiological investigations
find out the reasons
Control the further development of the disease
Terminate an outbreak or epidemic
Improve disease surveillance capabilities
Steps for an Outbreak Investigation
Prepare and organize
Verify diagnosis
Collect patients’ basic information, symptoms, signs and laboratory tests, and combine them with epidemiological data
Determine the existence of an outbreak
case definition
Uniform standards
Suspected cases, clinically diagnosed cases, laboratory confirmed cases
Case discovery and verification
Describe the three distributions of disease
Establish and test hypotheses
Source of infection, mode of transmission, risk factors, high-risk groups, dose-response relationship
case-control, cohort
Improve on-site investigation
real-time control measures
summary report
To prevent the outbreak of the disease, the top three (fake) companies are now reporting
Issues to note in outbreak investigations
Investigation and control proceed simultaneously
Make full use of legal weapons
ethical issues
extensive cooperation
media communication
Dispose
Prevention and control of infectious diseases
Source of infection
isolation
way for spreading
Disinfection and insecticide
Susceptible groups
personal protection
molecular epidemiology
Overview
Related concepts
molecular epidemiology
Population or biological group Medically relevant biomarkers—distribution, relationship with disease and health, and influencing factors—the science of studying strategies and measures to prevent disease and promote health
biomarkers
Exposure - Disease - measurable substances at the cellular, subcellular or molecular level that reflect changes in function or structure
Relationship to traditional epidemiology
same
From the distribution of diseases and health conditions - the relationship between exposure and outcomes, causes and influencing factors, and the development of strategies and measures to prevent diseases and promote health
different
Molecular and genetic level application of molecular biotechnology through biomarker assessment
Elucidate the distribution of biomarkers in the population and their relationship and influencing factors to disease and health - opening the black box
Macrolevel case-control and cohort studies
Elucidate associations with exposure to disease, but not pathogenesis
biomarkers
Exposed sign
External exposure
biological
Bacteria, viruses, parasites, toxins
abiotic
Physical chemistry (concentration of smoking smoke, content of elements and chemical substances in the environment, composition of dietary factors)
Before entering the body
internal exposure
Chemical poisons, dietary nutrients, carcinogens, microbial infections
Enter the body and be absorbed by the host
Effect flag
early effect sign
Cytotoxicity, chromosomal aberrations, DNA, RNA and protein expression, DNA methylation levels
Structural or functional change sign
proliferative precancerous lesions
clinical disease markers
Serum alpha-fetoprotein, carcinoembryonic antigen
Structural or functional changes after exposure
Susceptibility markers
genotype or phenotype
Evidence-based medicine and systematic reviews
evidence-based medicine
definition
Medical decisions should be based on the best available evidence, as well as personal clinical experience.
Practical basis
best research evidence
Highly qualified clinicians
Basic knowledge and basic methods of clinical epidemiology
patient involvement
Systematic review
definition
Standardized methods, a specific problem, relevant research reports, comprehensive and systematic collection, identification selection and rigorous evaluation, extraction of relevant data that meet the inclusion criteria, and comprehensive conclusions
feature
Clear title and purpose
Comprehensive search strategy
Inclusion and exclusion criteria
List all selected studies
Quality Evaluation
Troubleshooting causes
meta-analysis merge
Sensitivity analysis or heterogeneity test
Report results in a unified format
Comparison with traditional reviews
Collection and sources of literature: not systematic or comprehensive, and may be biased
Literature Screening: No Uniform Standard
Quality evaluation of literature: often not available, relatively casual
Qualitative analysis
Steps and methods
Selecting topics and formulating research plans
Search and collect original literature
Select eligible studies based on inclusion criteria
Assess the quality of selected studies
Obtain information, fill in the excerpt form, and build a database
Summary results
Heterogeneity test
meta-analysis
Sensitivity analysis and subgroup analysis
summary report
bias
publication bias
Literature search bias
citation bias
multiple publication bias
Biased inclusion criteria
weight bias
outbreak
public health emergency