实验诊断学(英文版)第一章.ppt

Chapter1GeneralofClinicalLaboratory LIPing Generalofclinicallaboratory PrinciplestoclinicallaboratoryTheinterpretationoflaboratorytestsTheethicalpractice Principletoclinicallaboratory ResponsibilitiesCollectionofInformationCollectionofSpecimens Informedconsent Adequateprivacy PerformanceofTestReportingofResultStorageandRetentionofMedicalRecordsAccesstoMedicalRecords Responsibilities Thepatient assurancethequalityandintegralityoftheserviceColleagueandprofessional maintainprofessionalreputation aimtocontributetheadvancementofprofessionSociety contributetothegeneralwell beingofsociety complywithrelevantlawsandregulationsofprofessionalactivities Collectionofinformation IdentifyadequatelypatientsandspecimensEnablethetesttobecorrectlyinterpretedOtherlegitimatepurposes Performanceofthetest Accreditationprogram Patientsinterests Processstandard Workswithhighskillandcompetence Goodperformanceoftests ReportingofResult Testresultsareconfidentialunlessdisclosureisauthorized ReporttheresultscorrectlyandtimelyProvidetheconsultationabouttheselectionandinterpretationoftestsproperly AccesstoMedicalRecords clinicianrequestingthetest thepatient laboratoryandhospitalstaffifrequiredforthemanagementofthepatient otherauthorizedindividuals Whenarequestismadeforaccesstotestresultsbyanauthorizedperson thelaboratorymustfirstsatisfyitselfastotheidentityofthepersonmakingtherequest Who INTERPRETLABORATORYTEST Selecttest Patientsprepareforsampling Collectspecimen Pre processofspecimen Analyzespecimen Check reportresult Makeclinicaldecision Biologicalvariability improperorinconsistentpreparation ImproperorinconsistantCollection Improperprovision suboptimumselection Analyticalvariabilty InadequateRVs MinimizevariabilityNoconfusionandmisunderstandingabouttestresults TestingCycle Biologicvariatinon Endogenousbiorhythmsforphysiologicparameters Differentconstitutionalfactorsandlifestyleamongsubjects within subjectvariation subject to subjectvariation Biologicalvariation Widthofthetest sReferencinterval RI thediagnosticefficiencyofalaboratorytest BiologicalrhythmsConstitutionalfactorsExtrinsicfactors ThreetypesofBiologicalrhythms Biologicvariation endogenousbiorhythmsforphysiologicparameters Differentconstitutionalfactorsandlifestyleamongsubjects within subjectvariation subject to subjectvariation Biologicalvariation Widthofthetest sReferencinterval RI thediagnosticefficiencyofalaboratorytest BiologicalrhythmsConstitutionalfactorsExtrinsicfactors Biologicvariabilty Constitutionalfactor infants children adults elderly rapidphysiologicchanges hemolysis bilirubin Plasmaproteinenzymesexhormones constantuntilmenopauseinwomenandmiddleageinmen age relateddifferencesinnutrition intercurrentdisease Agespecificreferencelimits age Age Biologicvariabilty Constitutionalfactor Geneticheterogeneity phenotypicdifferences Differentconcentrationofanalyte Differentreactivitytowardsnucleicacidprobesandantibodies false negative Misleading Geneticheterogeneity Biologicvariabilty ExtrinsicFactors vascularinterstitialspace supine stand H2OSmallanalyte plasmavolume Concentrationofnondiffusiblanalyte homeostasisofvasculartone renninaldosteronecatecholamines Posture Biologicvariabilty ExtrinsicFactors shiftsinplasmawaterglomerularfiltrationrateurineproductionreleaseofmacromoleculesfromcellsandtissues Exercise Biologicvariabilty ExtrinsicFactors mealrelatedfastingrelatedRecommendation durationoffastingbeforespecimencollectionistypically12hours TGTCBUNGLU LacAcetoneGlucagons Diet Biologicvariabilty ExtrinsicFactors TypesofInterference AnalyticalinterferencePhysiologicinterferenceRecommendation Recognizedrugs potentialforoccurrence withdrawmedicationsbeforesamplingwheneverpossible Evaluatanysuspiciousresultsinlightofasubject smedicationhistory Drug Biologicvariabilty ExtrinsicFactors plasmavolume erythrocytemass plasmaproteinsynthesis altereddistributionofcardiacoutput endocrinologicchanges hyperventilation Pregnancy Biologicvariation summary Biologicalrhythms Circadian Ultradian InfradianrhythmsConstitutinalfactors Gender age geneExtrinsicfactors Posture Exercise Diet Drugs Pregnancy Caffeine Alcoholuse OralContraceptives IntercurrentIllness EstablishandvalidateRVs Establishclinicalperformancecharacteristics Why HelpcliniciantoselectthemosteffectivetestsandtestingstrategiesHelpcliniciantotranslatelaboratoryresultsintoaprobabilitystatementHelpthelaboratorydirectortofocustheresourcesofthelaboratoryontestswiththehighestclinicalrelevance How Collectdata phaseIIandphaseIIIclinicaltrials EstablishandvalidateRVs Howtoassurethevalidityoftheparametersderivedfromclinicaltrials Usegoldstandardtodefineeverysubject sstatusAbroadspectrumofhealthyanddiseasedsubjects includepatientswithawiderangeofclinicalpresentations CIsshouldbecalculatedforalltheparametersthatareestimated Whennewtestcompareswiththeoldtest assuresampleofpatientslargeenoughanddataexactly SensitivityandSpecificity SensitivityandSpecificity ExpresstheprobabilitythatadiseasedsubjectwillhaveanabnormalresultExpresstheprobabilitythatanondiseasedpatientwillhavearesultwithintheRI Sensitivity Se TP TP FN Specificity Sp TN TN FP PredictiveValue TheprobabilitythatasubjectwithapositivetestresulttrulyhasthediseaseTheprobabilitythatasubjectwithanegativetestresulttrulyishealthy PVsareonlyaccuratewhenthetestisappliedtopopulationswithadiseaseprevalencethatissimilartothatofthestudysample PV TP TP FP PV TN TN FN Note ROCCurves WhatisROCcurveusedfor Determinethemostefficientdecisionthresholdorcutoffvalueforalaboratorytest Comparetherelativeclinicalaccuraciesofdifferentlaboratorytestsinaparticularclinicalsetting ROCCurves LikelihoodRatios LHRexpresstheprobabilitythataparticularwilloccurinadiseasedsubjectdividedbytheprobabilitythatthesameoutcomewilloccurinanondiseasedsubject Forcontinousvariabletest LHRscanbeestablishedfordifferentrangesoftestresults sothemagnitudeofatestresultprovidesadditionaldiscriminatorypower LHR Se 1 Sp TPrate FPrate LHR 1 Se Sp FNrate TNrate LikelihoodRatios TPraterepresentbenefitofthetest FPraterepresentsthecostsassociatedwithtesting soLHR representsacost benefitratio ItissimilartoLHR TheLHR andLHR allowthedirectestimationoftheposttestprobabilityofdiseaseinviewofthenewinformationcontributedbythetestresult LHR TPrate FPrate LikelihoodRatios LHRallowtheinformationfromdifferentmodalitiestobecombinedinserialdiagnosticschemesor criticalpathways forwhichoverallpredictivevaluescanbecalculated EstimatingLHRfromROCCurves LHRsforaparticulartestcanalsobeobtaineddirectlyformaROCcurvebyevaluatingtheslopesofthecurveindifferentregionscontinuousvariabletestpositive negativetesttestthatclassifiedintomorethantwointervals ETHICALPRACTICE Ethicalpracticecanberegardedasappropriatetechnicalpracticeaccompaniedbyintegrityinattitudesandbehavior Medicallabo