Sensitivity-WorldHealthOrganization世界卫生组织的敏感性

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1、SensitivityandspecificityPredictivevaluespositiveandnegativeInterpretationofresultsSep2007OutlineIntrinsiccharacteristicsofatestSensitivitySpecificityPerformanceofatestinapopulationPredictivevalueofapositivetestPredictivevalueofanegativetestSensitivitySensitivity=Truepositives/AffectedpersonsE

2、stimatethe95%confidenceintervalThesensitivityofatestintheabilityofthetesttoidentifycorrectlyaffectedindividualsProportionofpersonstestingpositiveamongaffectedindividualsEstimatingthesensitivityofatestIdentifyaffectedindividualswithagoldstandardObtainawidepanelofsamplesthatarerepresentativeofthep

3、opulationofaffectedindividualsRecentandoldcasesSevereandmildcasesVariousagesandsexesTesttheaffectedindividualsEstimatetheproportionofaffectedindividualsthatarepositivewiththetestEstimatingthesensitivityofarapidtestforleishmaniasisIdentifypersonswithleishmaniasiswithagoldstandardParasitologically

4、proveninfectionObtainawidepanelofsamplesthatarerepresentativeofthepopulationofindividualswithleishmaniasisRecentandoldcasesSevereandasymptomaticcasesVariousagesandsexesTestthepersonswithleishmaniasisEstimatetheproportionofpersonswithleishmaniasisthatarepositivewiththerapidtestSensitivityofarapid

5、testforleishmaniasisPatientswithleishmaniasisRapidtestTruepositive148Falsenegative2150Sensitivity=148/(150)=98%95%confidenceinterval:94%-99%Whatfactorsinfluencethesensitivityofatest?Characteristicsoftheaffectedpersons?YES:Antigeniccharacteristicsofthepathogeninthearea(e.g.,ifthetestwasnotprep

6、aredwithantigensreflectingthepopulationofpathogensinthearea,itwillnotpickupinfectedpersonsinthearea)Characteristicsofthenon-affectedpersons?NO:ThesensitivityisestimatedonapopulationofaffectedpersonsPrevalenceofthedisease?NO:ThesensitivityisestimatedonapopulationofaffectedpersonsSensitivityisanIN

7、TRINSICcharacteristicofthetestSpecificitySpecificity=Truenegatives/Non-affectedpersonsEstimatethe95%confidenceintervalThespecificityofatestintheabilityofthetesttoidentifycorrectlynon-affectedindividualsProportionofpersontes