第一名的学校流行病学课件.ppt

1、第一名的学校流行病学第一名的学校流行病学第一节第一节 病因的概念病因的概念 concepts of causation 鬼神、上帝、天意金金木木水水火火土土人人活的传染物迷信阶段迷信阶段朴素唯物主义朴素唯物主义生物学病因的萌芽生物学病因的萌芽病原物环境宿主三角模式三角模式生理社会物化机体轮状模式轮状模式病因网模型病因网模型一、疾病病因概念的发展一、疾病病因概念的发展（Development of causation in history）病因模型病因模型（causal model）F 三角模型（三角模型（epdemiological triad）F 疾病因素轮状模型（疾病因素轮状模型（whee

2、l model）F 病因网络模型病因网络模型(web of causation)Model of Disease环境环境 Environment病因病因 Agent宿主宿主 Host三角模型三角模型（epidemiological triad）宿主宿主环境环境病因病因健健 康（康（health）宿主宿主环境环境病因病因疾疾 病（病（disease）失衡失衡三角模型三角模型（epidemiological triad）A strong association between possible cause and effect,is more likely to be causal than a

3、weak association.（test and certification of hypothesis）当其中某个或多个因素不存在时，人群的疾病频率就会下降。例如戒烟与肺癌的关系研究中，我们发现戒烟后，人群肺癌死亡率下降。共变法（concomitant variations canon）reversibilitycriteria of causal inference 4-coherencePancreatic CancerFor example,smokers who give up smoking have a lower risk of lung cancer than those

4、 who continue to smoke.Environmental病因网络模型（web of causation）前因后果：唯一必须满足的标准例如戒烟与肺癌的关系研究中，我们发现戒烟后，人群肺癌死亡率下降。AssociationSocial/Psychologicalcriteria of causal inference 6dose-response relationshipServices,Social factors,and Spiritual factorsIncreased numbers of children not immunized against measles ca

5、uses the incidence rate for measles to go up.hypothesis developmentA strong association between possible cause and effect,is more likely to be causal than a weak association.环境病因宿主AgentEnvironmentalHost病因Agent环境Environmental宿主Host三角模型三角模型（epidemiological triad）病因Agent环境Environmental宿主Host三角模型三角模型（ep

6、idemiological triad）病因Agent环境Environmental宿主Host三角模型三角模型（epidemiological triad）EnvironmentalA strong association between possible cause and effect,is more likely to be causal than a weak association.criteria of causal inference 5-reversibility轮状模型（wheel model）例如戒烟与肺癌的关系研究中，我们发现戒烟后，人群肺癌死亡率下降。第一节 病因的概

7、念 concepts of causationHow do we know if the observed association reflects a causal relationship?Pancreatic Cancercriteria of causal inference 4-coherence因果推断标准(4)病因与疾病分布一致因果推断标准(2)关联的重复性Suppose we determine that an exposure is associated with disease.biologic plausibility这是强有力的反证病因关系的一种方法。因果推断标准(3)

8、时间顺序Age-standardized death rates due to well-established cases of bronchogenic carcinoma病因Agent环境Environmental宿主Host三角模型三角模型（epidemiological triad）病因Agent环境Environmental宿主Host三角模型三角模型（epidemiological triad）轮状模型轮状模型（wheel model）Human OrganismGenetic CodesSocial/Psychological EnvironmentChemical Envir

9、onmentBiological EnvironmentPhysical Environment生物环境生物环境社会环境社会环境遗传内核遗传内核理化环境理化环境宿主宿主健康健康 HealthHealth理化环境理化环境生物环境生物环境社会环境社会环境宿主宿主遗传内核遗传内核失衡失衡疾疾 病病 Disease轮状模型轮状模型（wheel model）生物环境生物环境社会环境社会环境理化环境理化环境先天性代谢异常先天性代谢异常Inborn error of metabolism 宿宿 主主遗传内核遗传内核健健 康康HealthNutritional factorsNon-CausalInborn

10、error of metabolismcriteria of causal inference 6dose-response relationshipAge-standardized death rates due to well-established cases of bronchogenic carcinoma例如戒烟与肺癌的关系研究中，我们发现戒烟后，人群肺癌死亡率下降。统计关联到因果关联From Epidemiological Association to CausationImmunologic factors因果推断标准(1)-关联的强度特异性的含义就是唯一性，病因特异性就是指唯

11、一的病因，疾病的特异性就是指唯一的疾病。Nutritional factorsNutritional factorsSpecificity indicate that a single exposure is associated with only one disease.EnvironmentalAssociation差异法（Method of difference）Environmental统计学关联（statistics association）因果推断标准(1)-关联的强度生物环境生物环境社会环境社会环境理化环境理化环境健健 康康Health 宿宿 主主遗传内核遗传内核麻疹麻疹Mea

12、sles For example,smokers who give up smoking have a lower risk of lung cancer than those who continue to smoke.虚假关联（spurious association）A dose-response relationship occurs when changes in the level of a possible cause are associated with changes in the magnitude of the effect.A causal relationship

13、would be recognized to exist whenever evidence indicates that the factors form part of the complex of circumstances that increases the probability of the occurrence of disease and that a diminution of one or more of these factors decreases the frequency of that disease.虚假关联（spurious association）一、因果

14、推断的一般过程Common process of causal inference统计关联到因果关联From Epidemiological Association to Causation差异法（different canon）三角模型（epidemiological triad）因果推断标准(1)-关联的强度dose-response relationship剩余法（residues canon）Morbidity and Mortality求同法（agreement canon）temporal sequence因果推断标准(1)-关联的强度Correlation between die

15、tary fat intake and breast cancer by countryIncreased numbers of children not immunized against measles causes the incidence rate for measles to go up.当其中某个或多个因素不存在时，人群的疾病频率就会下降。病因网络模型病因网络模型（web of causation）Morbidity and Mortality(Stroke,MI)Biological Risk Factors(Hypertension,Blood Lipids,Homocyst

16、eine)Genetic Risk Factors(Family History)Behavioral Risk Factors(Cigarette,Diet,Exercise)Environmental Factors(Socioeconomic Status,Work Environment)病因网络模型病因网络模型（web of causation）BEINGS ModelPreventable causes of diseaseiologic factors and Behavioral factorsnvironmental factorsmmunologic factorsutri

17、tional factorsenetic factorservices,Social factors,and Spiritual factorsA causal relationship would be recognized to exist whenever evidence indicates that the factors form part of the complex of circumstances that increases the probability of the occurrence of disease and that a diminution of one o

18、r more of these factors decreases the frequency of that disease.-Lilienfeld(1980)二、病因的定义二、病因的定义（definition of causation）Lilienfeld AMLilienfeld AM.（1920-19841920-1984）约翰约翰.霍普金斯大学流行病学教授霍普金斯大学流行病学教授 Lilienfeld AMLilienfeld AM.（1920-19841920-1984）约翰约翰.霍普金斯大学流行病学教授霍普金斯大学流行病学教授那些能使人群发病概率升高那些能使人群发病概率升高的因素

19、，就可认为是疾病的的因素，就可认为是疾病的病因；当其中某个或多个因病因；当其中某个或多个因素不存在时，人群的疾病频素不存在时，人群的疾病频率就会下降。率就会下降。二、病因的定义二、病因的定义（definition of causation）第二节第二节 因果关联的推断因果关联的推断 inference of causal associationEnvironmental ExposureorGenetic BackgroundorCombination of BothDisease or Other Outcome?Causation?AssociationSuppose we determi

20、ne that an exposure is associated with disease.How do we know if the observed association reflects a causal relationship?一、因果推断的一般过程一、因果推断的一般过程Common process of causal inferenceF 建立病因假设建立病因假设 hypothesis developmentF 病因假设的检验和验证病因假设的检验和验证 test and certification of hypothesisAssociation饮食脂肪摄入与乳腺癌发病Serv

21、ices,Social factors,and Spiritual factors(due to confounding)EnvironmentalCharacteristic Under StudyNutritional factorsconsistency共变法（concomitant variations canon）The frequency of a disease occurrence is extremely different under different situations or conditions.Non-Causal饮食脂肪摄入与乳腺癌发病Specificity i

22、ndicate that a single exposure is associated with only one disease.那些能使人群发病概率升高的因素，就可认为是疾病的病因；(Family History)test and certification of hypothesisHuman OrganismFor example,smokers who give up smoking have a lower risk of lung cancer than those who continue to smoke.统计学关联（statistics association）Human

23、 OrganismImmunologic factors密尔氏准则密尔氏准则 Mills canons建立病因假设建立病因假设（hypothesis development）密尔氏准则密尔氏准则（Mills canon)求同法求同法（Method of agreement）差异法差异法（Method of difference）共变法共变法（Method of concomitant variation）剩余法剩余法（Method of exclusion）If events or risk factors are common to a variety of different circum

24、stances and the events or risk factors have been positively associated with a disease,then the probability of that factor being the cause is extremely high.求同法求同法（agreement canon）v钩端螺旋体病流行，共同点钩端螺旋体病流行，共同点-下水劳动下水劳动The frequency of a disease occurrence is extremely different under different situations

25、 or conditions.If a risk factor or event can be identified in one condition and not in a second,it may be that factor,or the absence of it,that may be the cause of the disease.差异法差异法（different canon）v察布查尔病察布查尔病The frequency or strength of an event or risk factor varies with the frequency of the dise

26、ase or condition.Increased numbers of children not immunized against measles causes the incidence rate for measles to go up.共变法共变法（concomitant variations canon）v吸烟与肺癌；氟龋齿、斑釉齿吸烟与肺癌；氟龋齿、斑釉齿Subduct from any phenomenon such part as is known by previous inductions to be the effect of certain antecedents,

27、and the residue of the phenomenon is the remaining antecedents.剩余法剩余法（residues canon）v乙肝病毒黄曲霉毒素肝癌（藻类毒素）乙肝病毒黄曲霉毒素肝癌（藻类毒素）A 病例对照研究病例对照研究（case-control study）A 队列研究队列研究（cohort study）病因假设的检验和验证病因假设的检验和验证（test and certification of hypothesis）二、病因推断中暴露因素与疾病关联的解释二、病因推断中暴露因素与疾病关联的解释Association between exposu

28、re and disease in causal inferenceF 统计学关联统计学关联（statistics association）F 虚假关联虚假关联（spurious association）F 间接关联间接关联（indirectassociation）Interpreting Associations-Causal and Non-CausalCausal Non-Causal(due to confounding)Characteristic Under StudyCharacteristic Under StudyDiseaseFactor XDiseaseInterpret

29、ing Associations-Causal and Non-CausalCausal Non-Causal(due to confounding)Coffee ConsumptionCoffee ConsumptionPancreatic CancerSmokingPancreatic CancerSpuriousAssociationReal AssociationReal Association暴露与疾病暴露与疾病exposure and disease有无统计学关联有无统计学关联?statistical association有无偏倚有无偏倚?bias有时间先后否有时间先后否?tem

30、poral sequence统计关联到因果关联统计关联到因果关联From Epidemiological Association to Causation 关联的强度关联的强度 关联的重复性关联的重复性 关联的时间顺序关联的时间顺序 病因与疾病分布一致病因与疾病分布一致 终止效应终止效应 剂量反映关系剂量反映关系 关联的特异性关联的特异性 关联的生物学合理性关联的生物学合理性第三节第三节 病因推断标准病因推断标准criteria of causal inference strength consistency temporality coherence reversibility dose-r

31、esponse relationship specificity biologic plausibility因果推断标准因果推断标准(1)-(1)-关联的强度关联的强度关联强度越大，为因果的可能性越大关联强度越大，为因果的可能性越大 A strong association between possible cause and effect,is more likely to be causal than a weak association.关联强度的测定 measurement of strength RR,OR RR,ORcriteria of causal inference 1-st

32、rength因果推断标准因果推断标准(1)-(1)-关联的强度关联的强度criteria of causal inference 1-strength不同人群、不同地区、不同时间、不同类型的研究少数或个别研究不同甚或相反的结果并不能简单地反驳因果假设多数得到一致结果的研究可能遭遇共同的多数得到一致结果的研究可能遭遇共同的偏倚偏倚研究间不同的结果可能是因为某些因素的研究间不同的结果可能是因为某些因素的修正作用修正作用因果推断标准因果推断标准(2)(2)关联的重复性关联的重复性criteria of causal inference 2-consistency因果推断标准因果推断标准(3)(3)时

33、间顺序时间顺序前因后果：唯一必须满足的标准前因后果：唯一必须满足的标准实验性研究实验性研究队列研究队列研究采用新病例的病采用新病例的病例对照研究例对照研究生态趋势研究生态趋势研究横断面研究横断面研究时间时间暴露暴露结局结局criteria of causal inference 3-temporaliryThe cause must precede the effect.因果推断标准因果推断标准(4)(4)病因与疾病分布一致病因与疾病分布一致criteria of causal inference 4-coherence饮食脂肪摄入与乳腺癌发病饮食脂肪摄入与乳腺癌发病Correlation b

34、etween dietary fat intake and breast cancer by country 因果推断标准因果推断标准(5)(5)终止效应终止效应这是强有力的反证病因关系的一种方法。这是强有力的反证病因关系的一种方法。例如戒烟与肺癌的关系研究中，我们发现戒烟后，例如戒烟与肺癌的关系研究中，我们发现戒烟后，人群肺癌死亡率下降。人群肺癌死亡率下降。criteria of causal inference 5-reversibilityJ When removal of a possible cause results in reduction of disease risk,the

35、 likelihood of the association being causal is strengthenedJ For example,smokers who give up smoking have a lower risk of lung cancer than those who continue to smoke.When removal of a possible cause results in reduction of disease risk,the likelihood of the association being causal is strengthened差

36、异法（different canon）这是强有力的反证病因关系的一种方法。共变法（concomitant variations canon）共变法（concomitant variations canon）差异法（different canon）BEINGS ModelPreventable causes of diseaseHow do we know if the observed association reflects a causal relationship?乙肝病毒黄曲霉毒素肝癌（藻类毒素）Environmental factors三角模型（epdemiological tria

37、d）霍普金斯大学流行病学教授因果推断标准(1)-关联的强度The frequency of a disease occurrence is extremely different under different situations or conditions.Immunologic factorsbiologic plausibilityHow do we know if the observed association reflects a causal relationship?Suppose we determine that an exposure is associated wit

38、h disease.一、疾病病因概念的发展因果推断标准(2)关联的重复性一、疾病病因概念的发展饮食脂肪摄入与乳腺癌发病统计学关联（statistics association）三角模型（epidemiological triad）Coffee ConsumptionCoffee ConsumptionSocial/Psychological共变法（concomitant variations canon）For example,smokers who give up smoking have a lower risk of lung cancer than those who continue

39、 to smoke.(due to confounding)二、病因的定义（definition of causation）差异法（different canon）Age-standardized death rates due to well-established cases of bronchogenic carcinoma差异法（different canon）biologic plausibility(Cigarette,Diet,Exercise)temporal sequenceA strong association between possible cause and eff

40、ect,is more likely to be causal than a weak association.Association因果推断标准因果推断标准(6)(6)剂量反映关系剂量反映关系J A dose-response relationship occurs when changes in the level of a possible cause are associated with changes in the magnitude of the effect.criteria of causal inference 6dose-response relationship如果观察

41、到随着某因素暴露剂量的增加人群发生如果观察到随着某因素暴露剂量的增加人群发生某病的危险性增加，因果关联的强度增大，则称该因某病的危险性增加，因果关联的强度增大，则称该因素与该疾病之间存在剂量反应关系。素与该疾病之间存在剂量反应关系。Age-standardized death rates due to well-established cases of bronchogenic carcinoma因果推断标准因果推断标准(6)(6)剂量反映关系剂量反映关系每日吸烟量与支气管肺癌的年龄调整死亡率每日吸烟量与支气管肺癌的年龄调整死亡率criteria of causal inference 6do

42、se-response relationshipFor example,smokers who give up smoking have a lower risk of lung cancer than those who continue to smoke.差异法（different canon）因果推断标准(4)病因与疾病分布一致一、因果推断的一般过程Common process of causal inference三角模型（epidemiological triad）Pancreatic CancerEnvironmental(Family History)第一节 病因的概念 conc

43、epts of causationhypothesis developmentServices,Social factors,and Spiritual factors因果推断标准(1)-关联的强度这是强有力的反证病因关系的一种方法。乙肝病毒黄曲霉毒素肝癌（藻类毒素）因果推断标准(6)剂量反映关系因果推断标准(1)-关联的强度dose-response relationship(Cigarette,Diet,Exercise)For example,smokers who give up smoking have a lower risk of lung cancer than those w

44、ho continue to smoke.当其中某个或多个因素不存在时，人群的疾病频率就会下降。reversibilityCharacteristic Under StudyAssociationDisease or Other OutcomeHow do we know if the observed association reflects a causal relationship?biologic plausibilitybiologic plausibilityEnvironmental factorsCharacteristic Under StudyGenetic factors

45、第一节 病因的概念 concepts of causationAssociation关联强度越大，为因果的可能性越大病因网络模型（web of causation）病因模型（causal model）hypothesis development剩余法（residues canon）因果推断标准(3)时间顺序因果推断标准(6)剂量反映关系hypothesis development第二节 因果关联的推断 inference of causal association(Cigarette,Diet,Exercise)Nutritional factorscriteria of causal inf

46、erence 6dose-response relationshipFor example,smokers who give up smoking have a lower risk of lung cancer than those who continue to smoke.剩余法（residues canon）Environmental factorsImmunologic factorsNon-CausalAssociationAssociation环境 EnvironmentEnvironmentalstatistical associationA strong associatio

47、n between possible cause and effect,is more likely to be causal than a weak association.Genetic factors(Stroke,MI)乙肝病毒黄曲霉毒素肝癌（藻类毒素）共变法（concomitant variations canon）这是强有力的反证病因关系的一种方法。因果推断标准因果推断标准(7)(7)关联的特异性关联的特异性 特异性的含义就是唯一性，病因特异性就是指特异性的含义就是唯一性，病因特异性就是指唯一的病因，疾病的特异性就是指唯一的疾病。唯一的病因，疾病的特异性就是指唯一的疾病。Specificity indicate that a single exposure is associated with only one disease.criteria of causal inference 7specificity