流行病學英文討論課題目

Discussion2ClinicalTrialsCohortstudyCaseControlstudy第1頁Part1clinicaltrial1.1ResearchersconductarandomizedcontrolledtrialtodetermineifMedAreducespost-operativepainmorethanMedB.Theprimarypurposeofdoubleblindingthistrialistoavoid:A.recallbiasB.selectionbiasC.confoundingbiasD.non-random(differential)misclassificationofexposurestatusE.non-random(differential)misclassificationofoutcomestatus第2頁1.2Themainbenefitofarandomizedcontrolledtrial(RCT)comparedtoallotherepidemiologicstudydesignisthattheRCT:isprospectivetherebyeliminatingtheneedforhistoricaldatahasbetterexternalvalidityguaranteesthatconfoundingbiaswillnotoccurtendstoequallydistributeintothestudyarmscharacteristicswhichmaybeindependentriskfactorsfortheoutcomeofinteresttendstoavoidrandommisclassificationoftheoutcomeofinterest第3頁1.3

isamethodthatmaximizestheprobabilitythatthetwogroupswillbesimilarinbackgroundcharacteristicsthatmayinfluenceeithertheresponsetotherapyortheprimaryoutcomemeasure.blindingRandomizationdiagnosticcriteriaplacebo-controlledtrial.第4頁

1.4Filltheblankwith”yes”or“no”KnowledgeofTreatmentAssignmentBlindingPatient

InvestigatorNoneSingleDouble第5頁Resultsofthecoronaryarterydisease(CAD)TherapyTrialConcerningtheRiskofDevelopingMI

Treatment

myocardialinfarctionMedicineAMedicineBTotalYes9123114No287325612Total378348726第6頁1.5CalculatetheriskofdevelopingMIineachtreatmentgroup.1.6WhatisthepercentageofriskofMIthatwouldbeavoidedifMedicineBwereusedinsteadofMedicineA?1.7Whatisrelativeriskorrateratio?Howtoexplainitsepidemiologicalsignificance?第7頁Part2

Cohortstudy

CaseControlstudy

第8頁2.1whentheincidencerateofthediseaseisrare,whatkindofstudyismostsuitabletoexploretheunderlyingetiology?AProspectivestudyBcase-controlCdescriptivestudyDclinicaltrial第9頁2.2Foreachofthefollowingfeatures,indicatewhetheritbelongstoAfor

cohortstudyorBforcase-controlstudybestforcommonoutcomesgoodforrareoutcomesrelativelyinexpensiveoutcomeismeasuredafterexposureyieldstrueincidenceratesandrelativeriskssmallernumbersrequiredmayuncoverunanticipatedassociationswithoutcometakesalongtimetocompletecontrolsareselectedonthebasisofnothavingtheoutcomeoutcomeismeasuredbeforeexposure第10頁2.3IndicatenexttoeachstatementbelowwhetheryouconsiderittobeTRUE,orFALSEAnadvantageofcohortstudycomparedtothecasecontrolstudyisthatcohortstudiescandirectlyestimaterisks.Thetemporalsequenceofexposureanddiseasecanbedirectlyaddressedinacohortstudyaswellasinacasecontrolstudy.Adisadvantageofthecohortstudycomparedtoacasecontrolstudyisthatinacohortstudyonecannotaddressmultipleoutcomes.Adisadvantageofthecohortstudycomparedtoacasecontrolstudyisthatinacohortstudyoneneedstofollowalargenumberofparticipantsifthediseaseisrare.第11頁2.4Selectthecorrectstatement:a.)Theattributableriskistheexcessriskofdiseaseintheexposedcomparedtothenon-exposedduringadefinedperiodoftime.b.)Theattributableriskisaratioofthediseaseriskintheexposedcomparedtothenon-exposedduringadefinedperiodoftime.c.)Theattributableriskisaratioofthediseaseriskinthenon-exposedcomparedtotheexposedduringadefinedperiodoftime.d.)Theattributableriskistheprevalenceofdiseaseintheexposedminustheprevalenceofdiseaseinthenon-exposed.e.)Theattributableriskisthediseaseriskinadefinedgroupataspecificpointintime.第12頁Researchersinvestigatedthat100patientswithbladdercancerand600patientswithoutbladdercancer.20ofbladdercancerpatientssmoke,while40ofwithoutbladdercancerpatientssmokecigarettes.2.5Whatisthestudydesign?Calculatetheappropriatemeasureofassociationfordevelopingbladdercancerinsmokersvs.non-smokers.2.6Interpretthemeasureofassociationyoucalculatedinquestion.第13頁In1993acasecontrolstudywasconductedtoassessapossibleassociationbetweenservingintheGulfWarin1991andthesubsequentdiagnosisofneurologicaldiseases.Researcherscomparedthemilitaryrecordsof750ArmysoldiersseenforneurologicalsymptomsatWalterReedArmyHospitalin1992to1500ArmysoldiersseenatWalterReedHospitalthesameyearfornon-neurologicalsymptoms.第14頁Theresearchersusedmilitaryrecords,whichwereaccuratelymaintainedbyunitleaders,notthesubjectsthemselves,toestablishifeachsubjectdidordidnotserveintheGulfWar.ThestudyconcludedthatArmysoldierswhoservedintheGulfWarhad50%moreriskofhavingsubsequentneurologicaldiseasevs.thosewhodidnotserveintheGulfWar.第15頁2.13TheresearchersonlystudiedmaleArmysoldiers.Selectthebeststatement:A)ThefailuretostudyfemaleArmysoldiersisapossiblesourceofconfoundingbias.B)Recallbiasmayhaveledtomisclassificationofexposurestatus.C)Effectmodificationbysexmayaccountfortheobservedresult.D)Selectionbiasmayhaveaffectedtheresult.E)Interviewerbiasmayhaveproducedarandommisclassificationofexposurestatus第16頁2.14SubsequentanalysesshowedthattheinvestigatorsoftenfailedtoidentifysubjectswithmildneurologicaldiseasesamongthosewhodidnotserveintheGulfWar.Howmightthishaveaffectedtheriskestimates?Choosethebestanswer.A.)Itwouldhavebiasedtheestimatetowardsthenullvalueof1.0.B.)Itwouldhavebiasedtheestimateawayfromthenullvalueof1.0.C.)Itwouldhaveaffectedthestudy’sexternalvaliditybutnotitsinternalvalidity.D.)Theeffectcannotbereasonablydeterminedbasedontheinformationprovided.E.)Itwouldhaveresultedinnon-differentialmisclassificationofexposurestatus.第17頁SummaryWhatisthedifferencebetweenclinicaltrialandobservationalstudy?Advantagesanddisadvantages