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    首頁 Literature醫學英文原版高清電子書

    Literature醫學英文原版高清電子書.pdf

    Literature醫學英文原版高清電子書

    小嘎
    2018-04-02 0人閱讀 舉報 0 0 暫無簡介

    簡介:本文檔為《Literature醫學英文原版高清電子書pdf》,可適用于醫藥衛生領域

    Notlongago,caseseriespublishedbyasinglesurgeonorgroupofsurgeonsreportingtheresultsofanovelmanagementstrategyornewtechniquewerethemainstayofcommunicationinthesurgicalcommunityThesereportshighlightedsurgicaladvancesthatcouldbeappliedtopatients,butoftenreflectedthebestsurgeonsreportingtheirbestresultsSuchreportsrepresentedmuchoftheevidencebasethatguidedsurgicalpracticeHowever,withgrowingrecognitionthatalmosteveryonewillrequiresurgeryatsomepointintheirlives,surgicaldiseaseisbeingincreasinglyconsideredinthecontextofthepublicrsquoshealthFromthisperspective,thepublishedexperienceofonesurgeonbecomeslessrelevantthanevidencethatdescribeshowsurgicalproceduresactuallyworkinthegeneralcommunity,howtheireffectivenesscompareswithotherstrategies,andthefullspectrumofoutcomesneededtoassessaprocedurersquosimpactonpatientsandthehealthcaresystemOverthelastdecade,surgicalhealthservicesandoutcomesresearchhasemergedasanessentialapproachforinformingthemodernsurgicalerawithevidenceSurgicalinvestigatorsapplyarangeofresearchmethodstodrawtruthsfromthecollectivesurgicalexperience,withthegoalofintegratingthebestavailableevidenceintowhatsurgeonsdoingeneralpracticeDistinctfromthepasteraofsurgicalresearch,currenteffortsaimtomovebeyondreportingwhatcanbedonetopatientstoestablishingwhatshouldbedoneforpatientsOutcomesandhealthservicesresearcharebroadtermsforscientificinquiriesevaluatinghealthcareoutcomes,caredelivery,andthesystemsdeliveringthatcareThisenterprisedoesnotfocusonoutcomesalone,butalsoconsidersthedailyactionsperformedbyhealthcareteamsandsurgeons(processesofcare)aswellastheenvironmentinwhichservicesaredelivered(structuresofcare)Withthemedicalcommunityfacingincreasingregulatoryoversightandadriveformoreaccountablecare,itisessentialthatsurgeonsunderstandandembracetheapproachofevidencebasedsurgerysotheycanimprovethecareoftheirpatientsandmaintainaleadershiproleinhealthpolicyandqualityimprovementactivitiesThegoalofthischapteristohelpthereaderbecomeamorecriticalevaluatorofthesurgicalliteratureandadvancetheuseofbetterevidenceinsurgicalpracticeTothatend,thischapterisframedthroughquestionsthatacriticalreadershouldaskwhenreadingaresearchstudyWHATISTHEPURPOSEOFTHESTUDYAssessingthevalueofastudyrequiresanunderstandingoftheinvestigatorrsquosintendedpurposeMoststudiescanbeplacedintooneoftwogeneralcategories,descriptive(orexploratory)andanalytic(Fig)MostdescriptivestudiesshouldbeconsideredhypothesisgeneratingratherthancausalityfocusedwhereasanalyticstudiestestaprespecifiedhypothesisAstudyrsquospurposeshoulddrivetheselectionofstudygroups,outcomesofinterest,datasources,studydesign,andanalyticplanUnfortunately,manystudiesfallshortinlinkingstudypurposeandmethodologyinvestigatorsmaysometimestrytoestablishcausalityfromdescriptivestudiesForexample,inastudydescribingtrendsinthemisdiagnosisofappendicitisduringatimewhentherewasincreaseduseofdiagnostictesting,anattempttoestablishacausallinkbetweenthesetwofindings(ie,thetrendinmisdiagnosiswascausedbythetrendindiagnostictesting)wouldbeoverreachingthedescriptivenatureofthestudyTheintentofdescriptivestudiesshouldbeidentifyingpossibleassociationsandservingasanimpetusforfutureinvestigationsusingmorerigorousanalyticapproachesWHATISBEINGCOMPAREDManysurgicalstudiesevaluateoutcomes(eg,complications,cost,efficacy,effectiveness,qualityoflife,functionalstatus,patientsatisfaction)ofoneinterventionorstrategycomparedwithanotherThemethodofclassifyingsubjectsintoonegrouporanotherandthefactthatsomeexposuresvarywithtimeposeimportantmethodologicchallengestobeconsideredwhenevaluatingthestrengthofevidenceprovidedbyastudyMisclassificationMisclassificationistheincorrectcategorizationofasubjectintoastudygroupThisissueisimportantbecauseinthecontextofmisclassification,evenaproperlyperformedanalysiswithanappropriatestudydesignwillyieldbiasedresultsTherearetwowhatisthepurposeofthestudywhatisbeingcomparedwhatistheoutcomeofinterestwhatisthestudydesignwhatisthesourceofdataaretherenonanalyticissuesworthyofconsiderationhowwerethedataanalyzedarethereethicalconsiderationsconclusionsEVIDENCEBASEDSURGERY:CRITICALLYASSESSINGSURGICALLITERATUREDavidRFlum,FarhoodFarjah,andNaderMassarwehCHAPTEREvidEncEBasEdsurgEry:criticallyassEssingsurgicallitEraturEenspChapterenspenspSECTIONIsurgicalBasicPrinciPlEsstagedgroup,thereaderwouldhavetowonderwhethertheobserveddifferenceinsurvivalwasattributabletotheinterventionortodifferentialmisclassification(understaging)ofpatientsintheclinicallystagedgroupBycomparison,ifstaginginbothstudygroupswerebasedonaradiographicevaluation,eachpatientwouldhaveanequalchanceofbeingoverstagedorunderstagedFailuretodemonstrateadifferenceinoutcomebetweenthetwointerventionsmightbeafalsenegativefindingattributabletonondifferentialmisclassificationTimeVaryingExposuresTimevarying(ortimedependent)exposuresrefertopredictorswhosevaluemayvarywithtime(eg,smokingstatus,transplantationstatus)FailuretoaccountfortimevaryingexposuresintheanalysisofanobservationalstudymayleadtobiasedresultsandincorrectconclusionsAnexampleofpotentialbiasarisingfromtimevaryingcovariatesisananalysisofhearttransplantationsurvivaldataTheimpactofhearttransplantationonsurvivalwasassessedbycomparingpatientswhoreceivedatransplantwiththosewhodidnotAlthoughtheinitialanalysisrevealedasurvivalbenefitassociatedwithtransplantation,themannerinwhichpatientsweregrouped(treatingtransplantationasafixedvariable)ledtobiasinfavoroftransplantedpatientsTransplantationwaittimesareoftenlongandmanypatientsdiewhileawaitingadonororgantherefore,patientsonthetransplantationwaitlist,butwhodiedashorttimeafterbeinglisted,didnothaveachancetoundergotransplantationWhentheinvestigatorsretrospectivelyassignedpatientstothesetwostudygroups(transplantedversusnottransplanted),thepatientswhosurvivedlongenoughtoreceiveanewheartintroducedselectionbiasinfavoroftransplantation,becausetheirsurvivaltimeswereonaveragelongerthaninthenontransplantationgroupInactuality,eachsubjectrsquosexposurestatus(transplantedversusnottransplanted)wastimedependentWhileonthewaitlistandpriortotransplantation,asubjectcouldcontributesurvivaltimetothenontransplantationgroupsubsequenttotransplantation,thesamesubjectcouldthencontributesurvivaltimetothetransplantationgroupReanalysisofthedatatypesofmisclassification,nondifferentialanddifferentialNondifferentialmisclassificationindicatesanequalandrandomchancethatanyonesubjectwillbemisclassified(orincludedaspartofthewrongstudygroup)Withdifferentialmisclassification,thechanceasubjectismisclassifiedisnonrandomStagemigration,alsoknownastheWillRogersphenomenon,isaclassicexampleofmisclassificationCancerstagehasawelldefinedrelationshipwithlongtermsurvivalPatientsmaybestagedthroughclinicalexamination,radiographicassessment,invasiveprocedures,orpathologictissueexamination(thegoldstandard)StagingtechniquesotherthanpathologybasedapproachesmaybeinaccurateItisnotuncommonforhigheraccuracystagingmodalitiestobeassociatedwithhigherobservedsurvivalrateswhencomparedwithloweraccuracymethods(eg,aclinicalexamination)PatientsonlyassessedclinicallymightbeunderstagedmdashcategorizedasearlystagecancerbutactuallywithlatestagecancerSurvivalratesforearlystagepatientswouldthenbeworsethantheyreallywerebecausemisclassifiedlatestagepatientslowerthegroupaverageSimilarly,ifoverstagedpatientswereconsideredwithtrulylatestagepatients,survivalwouldbebetterthaninactualityThisphenomenonhasbeendemonstratedinastudyoflungcancerpatientsinwhichthosewhounderwentpathologicstaginghadbetteryearsurvivalratescomparedwiththosewhounderwentclinicalstagingIfadifferenceinoutcometrulyexistsbetweentwogroups,nondifferentialmisclassificationwillbiastheresultstowardthehypothesis,aconservativebiasWithdifferentialmisclassification,thebiasmaybeconservativeoranticonservative,dependingonthemannerinwhichpatientsweremisclassifiedandthetruerelationshipbetweengroupassignmentandoutcomeBecausenondifferentialerrorleadstoaconservativebias,preferabletononconservative,whichcouldleadtofalsepositivefindings,differentialmisclassificationisthemoreseriousconcernConsiderahypotheticalstudyofasurgicalinterventionforcancerinvolvingtwogroupsofpatients,oneclassifiedbasedonclinicalstagingandtheotheronpathologicstagingInthiscase,incorrectlyassumingthatbothgroupshavebeenequallyclassifiedwouldbeamistakeIfthestudydemonstratedasignificantbenefitforthesurgicalinterventioninthepathologicallyFIGUREHierarchyofstudydesignstheasteriskmeansthatthesamestudydesignsfoundintheotherbranchapplyTypesofstudydesignsAnalyticExperimentalObservationalRandomizedCrosssectionalCasecontrolCohortOtherExploratorydescriptiveObservational*SurveyCasereportseriesenspSeCtIONenspIsurgicalBasicPrinciPlEssafety,efficacy,oreffectiveness,PROsaremeasurablestudyoutcomesExamplesofcommonPROconceptsarehealthrelatedqualityoflife(HRQOL),satisfactionwithcare,functionalstatus,wellbeing,andhealthstatusPROsusuallyconsistofseveralmorediscreteconcepts(ordomains)HRQOL,forexample,ataminimum,shouldideallyincludedomainsthatmeasurephysical(eg,pain),psychological(eg,depression),andsocialfunctioning(eg,theabilitytocarryoutactivitiesofdailyliving)Specificexamplesofitemscontainedwithinthesedomainsmightincludepain,sleepproblems,sexualfunction,vitalityandenergy,andpain,anyorallofwhichmayberelevanttotheresearchquestionandarecertainlyofinteresttopatientsPROdataarecollectedthroughtheuseofsurveyinstrumentsTheseinstrumentsarecomposedofindividualquestions,statements,ortasksevaluatedbyapatientPROinstrumentsuseaclearlydefinedmethodforadministration,dataarecollectedusingastandardizedformat,andthescoring,analysis,andinterpretationofresultsshouldhavebeenvalidatedinthestudypopulationIngeneral,researchersareadvisedtouseexistinginstrumentstomeasurePROs(ratherthancreatingtheirown)becausetheappropriatedevelopmentofaninstrumentrequiressignificanttime,resources,testing,andvalidationbeforeapplicationKnowingwhetherthechoseninstrumenthasbeenvalidatedinthepopulationofinterestisalsoessentialwheninterpretingtheresultsandshouldbequestionedwhenreadingastudyreportingPROsAlthoughPROsrepresentauseful,informative,andimportantoutcome,theyaredifficulttomeasureaccuratelyandcanbecontroversialForexample,thereisoftenadisconnectbetweenwhatcliniciansandpatientbelievetobealowHRQOLassociatedwithachronicconditionWhenpatientsactuallyexperienceachronichealthconditionthatseemsintolerable,theymayshifttheirframeofreference,andthereisalsoadegreeofpatientadaptationthatisdifficulttoquantifyForinstance,thequalityoflifereportedbyanewlywheelchairboundpatientcomparedwithonewhohasbeeninawheelchairforanumberofyearscouldbedrasticallydifferentmdashtheformermightbequitelow,whereasthelattermightbehigherthananticipatedPartofthedifficultyisthatPROsareamoresubjective,lesstangibleoutcomethanmortalityorreadmissionHowever,incorporatingthesemeasuresintooutcomesassessmentisparamountincounselingfuturepatientsResourceUtilizationResourceutilizationreferstotheuseofhealthservicesrelatedtoaninterventionInthecontextofsurgicalcare,thisincludesutilizationofhospitalresourcesmdashlengthofstay,hospitalreadmission,useofoutpatient,pharmacy,anddurablemedicalequipment(eg,wheelchairsandoxygen)services,andemergencyroomuseDefiningcriteriaforexpectedutilizationischallengingandaverageuseisoftenconsideredasabenchmarkExcessresourceutilization,ascomparedwiththeaverage,isconsideredaninferioroutcomeandisoftenassociatedwithsomeformofcomplicationItcanbechallengingtodeterminehowmuchresourceutilizationisrelatedtotheinterventionorprocedureunderstudyandhowmuchisattributabletoapatientrsquosbaselineclinicalconditions(eg,chronicdisease,adverseevents)andnonclinicalfactors(eg,patientlevelsocialsupport,patientpreferenceforinhospitalversusoutofhospitalcare,insurancestatusprecludinguseofhomenursing)Forexample,aninvestigatormightuseMedicaredatatostudyevaluatingexposurestatusinatimedependentfashionrevealednoassociationbetweentransplantationandsurvivalWHATISTHEOUTCOMEOFINTERESTConcludingthatoperationAisbetterthanoperationBmustbesupportedbyevidenceofadifferenceinoutcomesButwhatdoesldquobetterrdquomeanWhatifoperationAisbetterwithregardtoonetypeofoutcomebutworseintermsofanotherOutcomesassessmentcannotdeterminewhichprocedureisbetterforthepatient,butitcaninformpatientsandprovidersaboutdifferencesbetweentwoormorecompetingtherapeuticoptionsReadersjudgingastudyrsquosvalueshoulddeterminewhichoutcomeswereassessed,fromwhatperspective,andwhetherthechosenoutcomeswereconsistentwiththestudyrsquosstatedaimsSafetySafetyendpointscapturetheinherentrisksofanoperation(eg,surgicalsiteinfection),naturalhistoryoftheunderlyingdiseaseprocessinthecontextoftherapy(eg,malignancyassociateddeepvenousthrombosisinapostoperativepatient),andorthesafetyofhealthcaredelivery(eg,wrongsitesurgery)Operativemortalityandpostoperativecomplications(morbidity)arethemostcommonlymeasuredmarkersofsafetySafetyendpointsareoftenusedinstudiesbecausetheyarerelativelyeasytomeasureandonlyrequireashortfollowupperiodtodeterminewhethertheeventoccurredHowever,thesearegenerallyrareevents,solargenumbersofpatientsareusuallynecessarytocharacterizetheassociationbetweenagiveninterventionandthechosensafetyoutcomeappropriatelyEffectivenessandEfficacyEfficacyreferstotheextenttowhichatreatmentinterventionachievesitspurportedbenefitandthedurabilityofthatresultEfficacyisusuallydeterminedinacontrolledresearchenvironment,requirescomparisonoftheselectedinterventiontoacontrolgroup,mayincluderandomization,andusuallynecessitateslongerfollowupForallthesereasons,efficacystudiesaremorechallengingtoexecuteandmoreexpensivetofundthansimpledescriptivestudiesArelatedoutcomeoftenconfusedwithefficacyiseffectivenessWhereasefficacyusuallyrelatestooutcomesinthecontextofresearchstudies(eg,randomizedtrials)andidealpatientcareconditions,effectivenessrelatestooutcomesinrealworldpracticeThedistinction,althoughsubtle,isanimportantonebecausemuchofthesurgicalliteratureiswrittenbyexpertsatacademiccentersandorcentersofexcellencethatmorecloselyapproximateidealpatientcareconditionsTheymayfailtocapturevariabilityinthequalityofcareprovidedbytheaveragephysicianatanaveragemedicalcenterinanaveragecommunityItisexactlyforthisreasonthatstudiesofcomparativeeffectiveness,comparingthebenefitsandharmsofdifferentinterventionsinrealworldsettings,havegainedincreasedattentionbecausetheyarebelievedtoprovidethehealthcarecommunitywithinformationonoutcomesthatmorecloselyapproximatesactualpracticeinthegeneralcommunityPatientReportedOutcomesPatientreportedoutcomes(PROs)measuresubjectiveoutcomes(termedconceptsinthePROliterature)ofcarereportedbythepatientdirectly,withourtherinterpretationofthisresponsebyaproviderorresearcherSimilartooutcomesinformingEvidEncEBasEdsurgEry:criticallyassEssingsurgicallitEraturEenspChapterenspenspSECTIONIsurgicalBasicPrinciPlEsThereareseveraldifferentmethodsforcomparativehealtheconomicanalysesAllmethodsconsiderthecostsofcareintermsofdollars,butdifferintermsofhowtheyquantifyhealthbenefitAcostbenefitanalysisquantifieshealthbenefitintermsofdollarsAlthougheasytocompareandinterpretsuchresults,thegreatchallengewiththisapproachisassigningadollarvaluetoalifeoraspecifichealthoutcomeAcostutilityanalysisquantifieshealthbenefitsintermsofqualityadjustedlifeyears(QALYs)Utilitiesareameasureofoverallqualityoflife,usuallyscaledbetweenand,withbeingperfecthealth,andareascertainedusingavisualanaloguescale,thetimetradeoff,orstandardgambletechniquesUtilitiesaremultipliedbysurvivaltimetodetermineQALYsWhenthisoutcomemetricisevaluatedasacostQALY,itisreadilycomparablebetweeninterventionsAninterventionwithanassociatedcostQALYof$,orlesshastypicallybeenconsideredcosteffectiveIntheoriginalMedicarelawthatincludeddialysisasapubliclyfundedtreatment,$,wasdeterminedtobethecostofdialysisHowever,thereisongoingdebateaboutthevalidityofthismetricandarangeofcostsQALYof$,to$,hasbeenproposedasmorereasonableCosteffectivenessanalysesmeasurehealthbenefitintermsofanoutcomemetriccalledtheincrementalcosteffectivenessratio(ICER),whichisthedifferenceincostsbetweentwocompetingtherapeuticoptionsdividedbythedifferenceinhealthoutcomeIftheICERcomparingatreatmentwithastandardrevealsthatitismoreexpensiveandlessefficacious,itisconsideredtobedominatedbythestandardandnotfavored,whereasalessexpensiveandmoreefficacioustreatmentdominatesthestandardandisfavoredCircumstancesinwhichaninterventionismoreexpensiveandefficaciousorlessexpensiveandefficaciousrepresentatradeoffSurrogateEndPointsInterestinsurrogateendpointshasemergedbecausedefinitiveclinicaloutcomesmaybedifficulttoassesssecondarytotheinfrequencyofachosenclinicalendpoint,thecostofascertainment,oralonglagtimetodevelopmentSurrogateendpointsarecommonlyusedinstudiesofnewpharmaceuticalinterventionswhenefficientdatagatheringabouttreatmenteffectisessentialtomoveaproducttothemarketplacerapidlyThetrueclinicalbenefitsofaninterventionmaytakeyearstorecognize,anditmaybedesirabletoidentifyanintermediateoutcomethatcouldserveasasurrogatefortheactualclinicaleffectUnfortunately,theproblemwithusingsurrogateendpointsisthataninterventionmayinfluenceanoutcomethroughvarious,andpotentiallyunintendedorunanticipated,pathwaysAclassicexampleillustratingthedangersofusingsurrogateendpointswastheCardiacArrhythmiaSuppressionTrialThisstudyhypothesizedthattheincidenceofsuddencardiacdeathcouldbereducedthroughtheadministrationofflecainideorencainideThesedrugsbecamepopularbecausetheyhadbeendesignedtoreducetherateofventricularectopy,acommonrhythmaberrancythoughttocausesuddencardiacdeathAlthoughthesedrugshadbeenshowntoreduceventricularectopy,whenmortality(aclinical,nonsurrogateendpoint)wasmeasuredinthistrial,administrationofthesedrugswasfoundtoresultinathreefoldincreaseintherateofdeathSuppressionofventricularectopywasthereforeapoorsurrogatefortheintendedclinicalimpact(improvedsurvival)oftheseagentsWhenevaluatingastudy,thereadermustnotonlyaskwhethertheselectedoutcomecananswertheresearchquestion,readmissionafterpancreaticresectionforcancerAlthoughreadmissioneventsarereadilyidentified,itisnotpossibletoknowwhetherthereadmissionwasplanned(forchemotherapyadministration)orunplanned(becauseofacomplication)ThechosentimelineforassessinghealthcareutilizationisalsocriticalOnlymeasuringimmediatehealthcareutilizationassociatedwithadiagnostictestwouldmissthepotentialdownstreamimpactonfuturediagnosticandtherapeuticcareLimitingassessmenttobriefperiodsmightmisspotentiallyimportantfutureimplicationsoverapatientrsquoslifeForexample,althoughthequalityanduseofhighresolutionimagingstudies(eg,computedtomographyCTscan)hasrisen,thenumberofincidentalomasidentified(eg,adrenal,lung,orliverlesionstoosmalltobediagnosedaccuratelyonimaging)hasconcurrentlyincreasedIfaninvestigatorhopedtodescribetheimpactofCTscanningasacancerscreeningmodality,onlymeasuringtheindividualscreeningstudywouldfailtocapturethedownstreameffectintheformofmultiple,costlyfollowupstudiesandorbiopsiestoevaluateanincidentalomafurtherCostsChargesaretheamountofmoneyrequestedforhealthservicesandsuppliesBycomparison,costsaretheactualamountofmoneyrequiredtodelivercareDifferentiatingthetwoiscriticalbecausehealtheconomicstudiesshouldaimtocharacterizethecostsofcareMostdatausedforhealtheconomicanalysesprovideinformationonhealthcarechargesIfchargesareevaluatedinsteadofcosts,aninterventionormanagementstrategywouldappearmoreexpensivethanitactuallyisWhenreadingthemethodssectionofsuchastudy,thecriticalreadermustlookforseveralimportantpointsFirst,theinvestigatorsshoulddescribeifandhowtheyconvertedchargestocosts,generallythroughtheuseofachargetocostratioSecond,costsshouldbediscounted(typically,to)toaccountforthefactthatadollartodaywillbeworthlessthanadollarinthefutureFinally,studiesspanningseveralyearsshouldadjustforinflationTheperceivedrelationshipbetweenhealthcareutilizationandcostsdependsontheperspective(eg,patient,provider,hospital,payer,orsocietal)takenbytheinvestigatorAhosp

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