东南大学流行病学课件

,case-controlstudy,HuiJinDepartmentofEpidemiologyandHealthStatisticsSchoolofPublicHealth,SoutheastUniversity,2,Overview,Designofcase-controlstudiesBasicconceptOR=RR?Exclusive(traditional)Inclusive(case-cohort)Concurrent(density)Case-to-caseCase-crossover,Whycase-controlstudy?,Inacohortstudy,youneedalargenumberofthesubjectstoobtainasufficientnumberofcase,especiallyifyouareinterestedinararedisease.GastriccancerincidenceinJapanesemale:128.5/100,000personyearAcase-controlstudyismoreefficientintermsofstudyoperation,time,andcost.,Case-controlstudy-Sequenceofdeterminingexposureandoutcomestatus,Step1:DetermineandselectcasesofyourresearchinterestStep2:SelectionofappropriatecontrolsStep3:Determineexposurestatusinbothcasesandcontrols,Caseascertainment,Whatisthedefinitionofthecase?Cancer(clinically?Pathologically?)Viruscarriers(Asymptomaticpatients)YouneedtoscreentheantibodyIncludingdeceasedcases?Youhavetodescribethefollowingpoints,thedefinitionwhen,where19:205-13.,Cases,SampleofsourcepopulationStillatrisk,Concurrentdesign:densitycasecontrol,49,Concurrentdesign:densitycasecontrol,ControlsselectedfromthosestillatriskwhenacaseoccursControlcanlaterbecomeacaseNotviceversa-casesnolongeratriskControlswholaterbecomecaseskeptinbothgroupsControlsrepresentpersonyearsatriskexperienceamongexposedandunexposedMatchedanalysisontimeofselectionORestimatestherateratio,50,Howtoselectcontrolstoestimatetherespectivemeasureofassociation,MeasureDesign,Formulation,Alternativeformulation,Controlstobesampledfrom,RiskratioInclusive,Ce/NeCu/Nu,Ce/CuNe/Nu,RateratioConcurrent,Ce/pyareCu/pyaru,Ce/Cupyare/pyaru,OddsratioExclusive,Ce/(Ne-Ce)Cu/(Nu-Cu),Ce/Cu(Ne-Ce)/(Nu-Cu),RodriguesLetal.IntJEpidemiol.1990;19:205-13.,Totalstudypopulationregardlessofpastorfuturediseasestatus,Peoplecurrentlyatrisk,Peopledisease-freethroughoutstudyperiod,51,Rarediseases:allgivesimilarresultsNon-recurrentdiseasewithhighincidence-Casecohortdesign(inclusive):ORrelativeRiskRecurrentcommondisease-Densitycasecontroldesign(concurrent):ORrelativeRateProbabilityoreffectofexposurechangesalongtime-Densitycasecontroldesign:ORrelativeRateNoneedtoquantify-traditionaldesign,Whatdesignandwhen?,52,RelationshipbetweenORandRR,accordingtotheprimaryattackrate(AR),Acknowledgements:OlivierlePolain,EPIETCohort15HPALondonEpidemiologyUnit,UK,53,Casesdetectedbysurveillancesystems,Non-randomselectionprocess:Hostfactors(eg.asymptomaticinfections)DifferenthealthcareseekingbehaviourIncompletelabinvestigationIncompletereportingDifferentialrecallBetweenreportedandnotreportedcasesBetweencasesandcontrols,54,Case-to-caseapproach,Samedisease,differentsubtypes/clones:SerotypesPhagetypesAntibioticresistancepatternsControls=caseswithnonepidemicsubtypesfromsamesourcepopulationsamesusceptibility(underlyingdiseases)includedascasesiftheyhadtheoutbreakstrainreadilyavailableReducesselectionANDrecallbiasFood-exposurecollectedbeforestatusisknown,55,Case-crossoverdesign,Samepersontakenasitsowncontrol-Nobetween-personsconfoundingMatcheddesign:CompareexposureinariskperiodtooneormorecontrolperiodsOnlypairsofdiscordantperiodsusedintheanalysisAcutediseasesExposuremustvaryovertimeshortinductionandtransienteffectsensitivetorecallbias,Referenceperiod,“Washout”,period,Currentperiod,CasesMatchedpairs1Discordant0,12Discordant1,03Concordant1,14Concordant0,0,Case-crossoverdesign,57,Folicacidantagonists(FAA)inpregnancyandcongenitalcardiovasculardefects(CCD),Case-crossoverapproachCase:WomanwhohadachildwithCCD(N=3870)Exposure:FAAduring2nd158:385-391,58,Conclusions,IfyoudonotneedthatORestimatescorrectlytheRR-“traditionaldesign”Otherwise,ifyouneedORRR-identifythebestdesignforeachsituationIfitisdifficulttofindappropriatecon