Sufficient cause: sufficient conditions for the occurrence of a disease, that is, a series of conditions, factors and events that at least make the disease occur. The presence of this factor will definitely cause the disease; and in the process of the disease, there may be a combined effect of multiple factors, which is sufficient. The cause may be composed of multiple components. We call these factors that work together as component causes. A single component cause is not enough to cause the disease.

Necessary cause: A specific factor must exist for a disease to occur. If the factor is missing, the disease will not occur. However, the necessary cause is not necessarily sufficient. That is, the necessary cause alone may not be enough to cause the disease, and other component causes are needed. Only when they participate and jointly form sufficient causes can the disease occur.

If there is only one sufficient cause for the occurrence of a disease, then each component of the sufficient cause is a necessary cause. For example, a pathogen is a necessary cause of an infectious disease. If the role of the pathogen is lacking, the infectious disease will not occur. At the same time, if there is a lack of transmission routes, And the disease will not occur in susceptible people.

Innate factors: genes, chromosomes, gender

Acquired factors: age, development, growth status, physique, behavior, psychology, acquired immunity

Biological environment: pathogenic microorganisms, parasites, harmful animals and plants (most infectious diseases and poisonings are the result of biological environmental factors)

Physical and chemical environment: meteorology, geography, water quality: air pollution

Social environment: population, family, eating habits, hobbies

cross-sectional study system case reporting ecological research

case control study array research

Clinical Trials Field Test community experiment

non-causal association

causal connection

1. The pathogen can be detected in patients with related diseases 2. The pathogen has not been found in other patients 3. The organism comes into contact with susceptible animals and can cause the susceptible animals to suffer from the same disease 4. It can be isolated from the infected animals to the same pathogen.

1. Time sequence of association

2.Strength of association

3. Specificity of association

4. Consistency or repeatability of association

5. Coherence or reasonableness of association

Key timing: the temporal sequence of exposure factors and disease occurrence, that is, the logical antecedents and consequences. This standard is a necessary condition and an absolute standard

Strength of the key: the degree of association between exposure and disease. Indicators: ratio OR, relative risk RR, correlation coefficient

Dose-response relationship: Frequency of disease as a function of exposure

Key reproducibility: Different researchers conduct studies on the association between a certain exposure factor and a certain disease using different research methods in different populations and times, and they can all observe the same research results.

Key specificity: The occurrence of a certain disease must occur after a certain factor, or the exposure of a certain factor can only cause a specific disease.

Experimental evidence: Epidemiological experimental methods remove the experimental cause of a certain disease, causing a certain morbidity or mortality rate to decrease or reach zero, indicating that there is a termination effect in the causal relationship. Experimental evidence can come from population field trials, clinical trials, and basic medical experiments.

Reasonability of association: 1. The causal association discovered should be biologically reasonable. It should be consistent with the natural history and biology of the disease. 2 Researchers or evaluators should start from the background of professional knowledge when making assumptions about causal relationships. essential

Critical consistency: Not much different from critical plausibility.