何纳-流行病学病因模型回顾与展望
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III. Effect preventive 预防效应
IV. No effect (“immune”) 无病因效应
Hypothetical Condition
Exposed 暴露
Case 病例
Case 病例
Noncase 非病例
Noncase 非病例
Unexposed 非暴露
Case 病例
Noncase 非病例
• This general approach is the “epidemiologic method”.
By assessing the statistical association in this way, we attempt to
• The validity of this comparison between exposed and unexposed populations, however, depends on the comparability of exposure groups with respect to the distribution of the 4 causal types.
1
Sufficient Cause Model
ቤተ መጻሕፍቲ ባይዱ
Sufficient Cause and Component Causes
• A cause of a disease event is an event, condition, or characteristics that preceded the disease event and without which the disease event either would not have occurred at all or would not have occurred until some later time
流行病学病因模型
----回顾与展望
何纳 复旦大学公共卫生学院
2019.7.18 昆明
Deterministic/Counterfactual Cause Model
个体水平上的病因学类型
Type of individual 个体的病因学类型
I. No Effect (“doomed”) 无病因效应
II. Effect causative 致病效应
• With this definition, it may be that no specific event, condition, or characteristic is sufficient by itself to produce disease
• This definition does not define a complete causal
• We observe whether the disease is more or less frequent in the exposed group than in the unexposed group ---- i.e., we assess the statistical association between exposure status and disease status in the study pop.
• Since we cannot observe the outcome in exactly the same way under both exposure conditions for the same individuals, in epidemiology we must compare a group of individuals who were exposed with a group of individuals who were unexposed.
• Suppose that U is always present (ubiquitous) and the above figure represents all the sufficient causes.
• For example, it would not be valid to compare a group of exposed persons who were all Type 1s with an unexposed group who were all Type 4s; the exposed would get the disease and the unexposed would not, even though the exposure has no biologic effect in any member of these groups
• Thus, if we observe the actual outcome of one individual, e.g., an exposed person who becomes a case, we cannot determine whether the exposure had an effect on the disease. Is that exposed case a Type I or a Type II?
Case 病例
Noncase 非病例
• The exposure has a biologic effect on the disease in Types II and III, but not in Types 1 and 4
• In practice, we cannot observe these types because we cannot observe both exposure states simultaneously in the same individuals. A given person is either exposed or unexposed, I.e., one exposure condition is counterfactual (counter to fact---not observed)
IV. No effect (“immune”) 无病因效应
Hypothetical Condition
Exposed 暴露
Case 病例
Case 病例
Noncase 非病例
Noncase 非病例
Unexposed 非暴露
Case 病例
Noncase 非病例
• This general approach is the “epidemiologic method”.
By assessing the statistical association in this way, we attempt to
• The validity of this comparison between exposed and unexposed populations, however, depends on the comparability of exposure groups with respect to the distribution of the 4 causal types.
1
Sufficient Cause Model
ቤተ መጻሕፍቲ ባይዱ
Sufficient Cause and Component Causes
• A cause of a disease event is an event, condition, or characteristics that preceded the disease event and without which the disease event either would not have occurred at all or would not have occurred until some later time
流行病学病因模型
----回顾与展望
何纳 复旦大学公共卫生学院
2019.7.18 昆明
Deterministic/Counterfactual Cause Model
个体水平上的病因学类型
Type of individual 个体的病因学类型
I. No Effect (“doomed”) 无病因效应
II. Effect causative 致病效应
• With this definition, it may be that no specific event, condition, or characteristic is sufficient by itself to produce disease
• This definition does not define a complete causal
• We observe whether the disease is more or less frequent in the exposed group than in the unexposed group ---- i.e., we assess the statistical association between exposure status and disease status in the study pop.
• Since we cannot observe the outcome in exactly the same way under both exposure conditions for the same individuals, in epidemiology we must compare a group of individuals who were exposed with a group of individuals who were unexposed.
• Suppose that U is always present (ubiquitous) and the above figure represents all the sufficient causes.
• For example, it would not be valid to compare a group of exposed persons who were all Type 1s with an unexposed group who were all Type 4s; the exposed would get the disease and the unexposed would not, even though the exposure has no biologic effect in any member of these groups
• Thus, if we observe the actual outcome of one individual, e.g., an exposed person who becomes a case, we cannot determine whether the exposure had an effect on the disease. Is that exposed case a Type I or a Type II?
Case 病例
Noncase 非病例
• The exposure has a biologic effect on the disease in Types II and III, but not in Types 1 and 4
• In practice, we cannot observe these types because we cannot observe both exposure states simultaneously in the same individuals. A given person is either exposed or unexposed, I.e., one exposure condition is counterfactual (counter to fact---not observed)