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1、诊断试验评价 案例讨论严卫丽教授博士新医大公共卫生学院流行病学与卫生统计学教研室电话：4366351Email：01.weili@gmail.comScreeningtestoutcomes:Fordichotomous-positiveornegativeForcontinuous-categorizetopositiveornegativeIfscreeningtestfindingis:PositiveNegativeright:truepositivewrong:falsepositiverigh
2、t:truenegativewrong:falsenegativePopulationrealityDiseaseNodiseaseTestresultsPositiveNegativeTruePositiveTrueNegativeFalseNegativeFalsePositiveSensitivity=Specificity=TPabilitytoidentifyTP+FNthosewithdiseaseTNabilitytoidentifyTN+FPthosew/odiseaseTruechara
3、cteristicsinthepopulationDiseaseNodiseaseResultsofscreeningPositiveNegative8080020100Sensitivity==80%Specificity==89%80100800900Example:Pop:1000w/dis:100w/odis:9001009001000820180TotalResultofaDichotomousTest withDiseaseStatusTruepositive(TP)=Havediseasea
4、ndhavepositivetestFalsepositive(FP)=Nodisease,buthavepositivetestFalsenegative(FN)=Havedisease,buthavenegativetestTruenegative(TN)=NodiseaseandhavenegativetestWithDiseaseW/ODiseasePopulationTestResultsPositiveNegativePredictiveValueofaTestIfthetestresults
5、arepositiveinthispatient,whatistheprobabilitythatthispatienthasthedisease?Whatproportionofpatientswhotestpositiveactuallyhavethediseaseinquestion?PositivePredictiveValueofaTest:PPV=NegativePredictivevalue:Withnegativeresult,whatistheprobabilitythatthepati
6、entdoesnothavethedisease?NPV=TruepositiveTotalpositiveTrueNegativeTotalnegativeRelationshipbetweenPredictiveValueandPrevalencePredictivevalueimprovesasprevalenceincreases.RelationshipbetweenPredictiveValueandSpecificityPredictivevalueimprovesasspecificity
7、ofascreeningtestincreases.ContinuousVariables:CutoffDefininglevelofriskfactorforintervention:lipids,bloodpressure,glucose,CRP,etcWhatlevelcutoffformedicalintervention?cholesterol:fromLRCtoHPSWhattest?cholesterol:LDL,HDL,ratio,nonHDL-C,triglycerides&glucos
8、e:fastingorpostprandialIsLDL/HDLratiobetterthanLDL?Betterforwhat?IsOGTTbetterthanFPG?Betterforwhat?ScreeningforType2Diabetes:StrongHeartStudyWang,DiabetesCare,2002.ROCanalysesofwaistcircumference,Waist-to-hipratio,a
