文档介绍：case-controlstudyHuiJinDepartmentofEpidemiologyandHealthStatisticsSchoolofPublicHealth,SoutheastUniversity*OverviewDesignofcase-onceptOR=RR?Exclusive(traditional)Inclusive(case-cohort)Concurrent(density)Case-to-caseCase-crossoverWhycase-controlstudy?Inacohortstudy,youneedalargenumberofthesubjectstoobtainasufficientnumberofcase,:,000personyearAcase-controlstudyismoreefficientintermsofstudyoperation,time,-controlstudy -estatusStep1:DetermineandselectcasesofyourresearchinterestStep2:SelectionofappropriatecontrolsStep3:DetermineexposurestatusinbothcasesandcontrolsCaseascertainmentWhatisthedefinitionofthecase?Cancer(clinically?Pathologically?)Viruscarriers(Asymptomaticpatients) →YouneedtoscreentheantibodyIncludingdeceasedcases?Youhavetodescribethefollowingpoints,thedefinitionwhen,where&howtoselectCasedefinitionConceptualdefinitionObesitydefinedasbodyfatpercentage>33%OperationaldefinitionBodyMassIndex>30Casedefinition:IssuesCasedefinitionshouldavoidmisclassificationForexample:Sinhaetal(2008)AnemiawasdefinedasHemoglobin<110gm/LasmeasuredbyWHOColourScaleWHOColourScaleover-estimatesthehemoglobinMisclassifiedcaseswithmildanemiaAlso,studyingmildformsofcases,giveslargercasegroup;butmisclassifiescasesasnon-casesORnon-casesascasesasearlydiagnosisisgenerallyimpreciseCasedefinition:IssuesAseverecasedefinitionmayexcludepeoplewhohavebeencuredorwhodiedofdiseasebeforetheconditionwassevereenoughtobelabelledascaseStandard/consensusdefinitionsifavailable,mustbeusedForexample,Rheumatoidarthritis–Romecriteria,NYcriteria,riteriaMetabolicSyndrome–ATPIII,IDRF,andsoonLackofagreementoverdefinitionmayintroducevariabilityinestimatesofeffectCasedefinition:IssuesTheissuesofseverity,riteriaandsubjectivityofcriteriaallleadtopotentialproblemsofmisclassificationofcasesTheresearchercanchoosebetweenmorerestrictiveandinclusivedefinitionsThinkintermsofsensitivityandspecificityofdefinitionanditseffectonvalidity,sample