Clinical Thinking: Evidence, Communication and Decision-Making PDF
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Clinical Thinking Clinical Thinking Evidence, Communication and Decision-Making Chris Del Mar BondUniversity,Queensland,Australia Jenny Doust UniversityofQueensland,Queensland,Australia Paul Glasziou UniversityofOxford,Oxford,UK (cid:2)C 2006ChrisDelMar,JennyDoustandPaulGlasziou PublishedbyBlackwellPublishingLtd BMJBooksisanimprintoftheBMJPublishingGroupLimited,usedunderlicence BlackwellPublishingInc.,350MainStreet,Malden,Massachusetts02148-5020,USA BlackwellPublishingLtd,9600GarsingtonRoad,OxfordOX42DQ,UK BlackwellPublishingAsiaPtyLtd,550SwanstonStreet,Carlton,Victoria3053,Australia TherightoftheAuthortobeidentifiedastheAuthorofthisWorkhasbeenassertedin accordancewiththeCopyright,DesignsandPatentsAct1988. Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrieval system,ortransmitted,inanyformorbyanymeans,electronic,mechanical, photocopying,recordingorotherwise,exceptaspermittedbytheUKCopyright, DesignsandPatentsAct1988,withoutthepriorpermissionofthepublisher. Firstpublished2006 1 2006 LibraryofCongressCataloging-in-PublicationData DelMar,Chris. Clinicalthinking:evidence,communicationanddecision-making/ChrisDelMar, JennyDoust,PaulGlasziou. p.;cm. Includesbibliographicalreferences. ISBN-13:978-0-7279-1741-6 ISBN-10:0-7279-1741-2 1.Clinicalmedicine–Decisionmaking. 2.Evidence-basedmedicine. [DNLM:1.PatientCareManagement–methods. 2.Communication. 3.DecisionMaking. 4.DiagnosticTechniquesandProcedures. 5.Evidence-Based Medicine–methods. 6.ProblemSolving.W84.7D359c2006] I.Doust,Jenny. II.Glasziou,Paul,1954- III.Title. R723.5.D452006 616–dc22 2005037642 ISBN-13:978-0-7279-1741-6 ISBN-10:0-7279-1741-2 AcataloguerecordforthistitleisavailablefromtheBritishLibrary Setin9.5/12ptMeridienbyTechBooks,India PrintedandboundinSingaporebyFabulousPrintersPteLtd CommissioningEditor:MaryBanks EditorialAssistant:VictoriaPittman DevelopmentEditor:ElisabethDodds ProductionController:KateCharman ForfurtherinformationonBlackwellPublishing,visitourwebsite: www.blackwellpublishing.com Thepublisher’spolicyistousepermanentpaperfrommillsthatoperateasustainable forestrypolicy,andwhichhasbeenmanufacturedfrompulpprocessedusingacid-free andelementarychlorine-freepractices.Furthermore,thepublisherensuresthatthetext paperandcoverboardusedhavemetacceptableenvironmentalaccreditationstandards. Contents Foreword,vii Preface:whatthisbookisabout,ix Chapter1 Principlesofclinicalproblemsolving,1 Chapter2 Communicationinclinicalcare,12 Chapter3 Modelsofdisease,27 Chapter4 Diagnosis,38 Chapter5 Fineartofprognostication,58 Chapter6 Makingclinicalmanagementdecisions,71 Chapter7 Monitoringinchronicdisease,84 Chapter8 Screeningfordisease,healthpromotionand diseaseprevention,99 Chapter9 Endpiece,114 References,115 Index,123 v Foreword Every experienced doctor appreciates – and every newly-qualified doctor quicklydiscovers–thatknowingthefactsisnotthesameasknowingwhatto do.Diseasesdon’tconformtothetextbookversions.Patientscanbeidiosyn- cratic and sometimes irrational. So can doctors. Research evidence is often inconsistent,andeventhemostup-to-datepaperisneverthelastword.The so-calledinformationexplosioncanconfuseaseasilyasitcanilluminate.Ev- ery protocol, guideline and code of good practice immediately reminds the practisingclinicianofahundredexceptions. The hallmark of the trustworthy doctor – many would say it is a defining characteristicofatrueprofessional–istheabilitytomakejudgementsinthe faceofuncertainty.Doctorshavetobegoodatinterpreting,atprioritising,at makingcompromises,atseeingwhatmattersamidawelterofcomplication, andatsometimesinsistingthatwhatseemsrightintheorywouldbedamaging intheflesh.Facedwithsuchacomplextask,itistemptingtotakerefugeina numberofeasybutflawedpositions.‘IwillonlyeverdowhatIcanjustifywith evidence’isonesuch.‘I’lljustdowhatIalwaysdo,orwhatmyteachersalways did’isanother.Butthefirstsoonleadstoparalysis,thesecondtodangerous sloppiness.Soundclinicalthinking,andtheprofessionaljudgementthatflows fromit,isneitherslavishlyobedienttoanyrulenorrecklesslydisregardingof thebestavailableinformation. Thequestionfordoctorsateverystageoftheircareersishowtheirthinking skillsaretobeacquired,developed,honed,maintained,andprotectedagainst inertiaandatrophy.Surfingtheexponentialwaveofnewknowledgeisnec- essary,butnotsufficient.Preservingone’sfascinationwithhumannaturein itsmanymanifestationsthroughliterature,theartsandhumanitiesishelpful, desirable,butnot–forsomespecialitiesatleast–essential.Thenecessarycom- plementtoboththeseistocultivatethehabitofcriticalreflectionuponone’s ownpractice,conductedwithgenuinecuriosityandhumility.Self-reflection isanotherdefiningcharacteristicofatrueprofessional,andthatiswhatthis book embodies. To read it is to learn the value of thinking about how one thinks. The reader will benefit, but his or her patients will do so in greater measure.Patientsdeservetohavedoctorswhonotonlyknowtheirstuffbut alsoknowhowtoapplythatknowledgetothehumanpredicamentsthatdaily confrontthem. RogerNeighbourMADScFRCPPRCGP President,RoyalCollegeofGeneralPractitioners Bedmond,December2005 vii Preface: what this book is about Thisbookisdesignedtohelppeopleunderstandtheclinicalthinkingneeded topracticesuccessfully. It is based on the simple notion that there are two sorts of learning that we need for practice: knowledge and skills (of the diagnosis and manage- mentofdiseasesandassociatedsymptoms),andtheabilitytosynthesisethis information into clinical decisions. The knowledge and skills can be further subdivided into background information (the basic information, made up of anatomy,biochemistry,physiology,psychology,pathologyandsoon)needed to understand the principles of caring for sick people, and the foreground in- formation(theresearchwhichbestguidesmanagement). Practicing medicine is not just about recalling facts, however. It is about being able to process the facts in order to make choices. All of clinical work canbethoughtofasdecisions,evensuchhands-onskill-basedactivitiessuch assurgery.Ofcourse,thefirstsetoflearningenablesonetodecidewhatthe choicesare.Buthavingassembledthenecessaryinformation,howdoesone goaboutdecidingwhatactuallytodo? The major revolution in foreground information has been the rising star of evidence-based practice (EBP), or evidence-based medicine (EBM). This has changedthewaywethinkofknowledge:nolongerthestaticstuffthatcanbe hauledoutofbooksorstuffedintotheheadsofmedicalstudentsandregistrars, butsomethingdynamicthatweshouldbepullingdownelectronically,often, andnotevenbotheringtorememberbecauseitwillbeoutofdatebythetime wehavecommittedittomemory.WeallthreeareveryinterestedinEBP.But thatisnotthesubjectofthislittlebook.Ratherwewrotethistohelpsetout (as much as anything for our own minds!) some of the cognitive processes that we think make it easier to apply the knowledge and skills into clinical practice.Wethreedecided,whileenjoyingthebrainstormingthatwentinto preparingforthebook,thatwewishedsomethinglikeithadbeenwrittenfor uswhenwewerestudentsandregistrars. Whatwehavedoneinthisbookistogathertogetherwhatisknownabout the art and the science of how we use the facts of medicine to solve the problemswefaceasclinicians.Someofthescienceiscounter-intuitive.This iswhatmakesitsofascinating.Wehaveincludedsomeoftheitemsthatwe findhelpfulorunexpected,andtriedtosynthesisethemintoastory.Hopefully youtoowillfindthatthisisnotonlyhelpful,butalsomakesclinicalpractice evenmorefun.Whereevidenceforsomeofthemoreoutrageousclaimsexists ix x Preface:whatthisbookisabout n Background information o ati m or nf of i nt u o Foreground information m A Time: maturation as a clinician → Figure Differenttypesofinformationneededforsuccessfulclinicalpractice.Adapted fromSackettetal.1 we have quoted it. But on the whole this book is not so much an academic exerciseasahandbook.Hopefully,itwillhelpusalltobebetterclinicians.We hopeyoufinditso. The way the book is written is to set out the framework of the thinking in chapters. We often illustrate the principles with a ‘case’ (many from our ownpractices)tohelpshowhowtheymightbeapplied,andthenattheend of each section we show how they could be applied into clinical practice by explainingthemtothe‘patient’asadialogue. Whoarewe?WeareacademicgeneralpractitionerswhometupinQueens- land. We all worked in the same clinical general practice while we worked togetherinacademia,beforespreadingout.Wedidacertainamountofsitting around,drinkinggreenteaandthinkingaboutthisbook.Oneconsequenceof ourbackgroundisthatourexamplesarefirmlybasedonprimarycare.Forthis wemakenoapology.Wethinkthatifonecangetclinicalthinkingtobeuse- fulingeneralpractice,thatseatofthegreatestunknown,leastdifferentiated disease,thenitislikelytobeusefulalmostanywhereinclinicalpractice. Wededicatethebooktopatients,forwhomwehopethiswillmakeadif- ference,reducetheirsuffering,andhelptheirdoctorsmanagetheirillnesses better. ChrisDelMar JennyDoust PaulGlasziou Clinical Thinking: Evidence, Communication and Decision-Making Chris Del Mar, Jenny Doust, Paul Glasziou Copyright © 2006 by Chris Del Mar, Jenny Doust and Paul Glasziou CHAPTER 1 Principles of clinical problem solving Doctors constantly make decisions. It may not always feel like this. In fact, if we have been in practice for a while, it can begin to feel as if much of ourpracticeisroutine.Thisisbecause‘whenthingsareproceedingnormally, expertsdon’tsolveproblemsanddon’tmakedecisions:theydowhatnormally works’.2 Part of becoming a competent doctor is learning the vast number of facts necessarytopracticemedicine.Themoreimportantpartofourlearningisto modelthedecision-makingbehaviourofmoreexperiencedclinicians,learning the routines that they use to collect and process the facts of each new case and thereby learn to make the sort of decisions that we all need to make as clinicians(seeBox1.1). Ourclinicaltraininggivesusthecontextandtheexperiencetoprocessthe informationofeachnewpatientandtomapitagainstourstoreofmemorised facts.Thewaythatwelistentoandrecountthestoriesofourpatientsbecomes ritualised,withstrictruleslikeaGreekchorus.Thetextbookfactsthatwehave learntbegintoattachthemselvestoexperience,tothestoriesofourpatients and to our own experience of working in health care. We now know that clinical knowledge is mostly stored in memory as stories or templates, and notascollectionsofabstractedfacts.3 Aswegainclinicalexperience,weare graduallyabletousethedetailsthatweseeandhearwithbetterdiscrimination and with time we come to make decisions more or less intuitively, and may evenfinditdifficulttoexplaintheintermediatestepsinourclinicalreasoning (Box1.2). Box1.1 ExamplesofTypicalClinicalDecisions (cid:2)ShouldIdoatest?WhichtestshouldIdo? (cid:2)CouldIbemissingadiagnosis?ShouldIbeinvestigatingthispatient further? (cid:2)WhichoftheavailabledrugsshouldIprescribe?Wouldthepatientbe betterwithoutfurthermedication? (cid:2)Isitalrighttodividethisstructureduringtheoperation–amIsureitis aveinandnotanerve...? (cid:2)ShouldIaskthepatienttocomeback?When?Howoften? 1 2 Chapter1 Box1.2 CharacteristicsofNovice,CompetentandExpert Practitioners4 Thenovicepractitionerischaracterisedby: Rigidadherencetotaughtrulesorplans Littlesituationalperception Nodiscretionaryjudgment Thecompetentpractitioner: Isabletocopewith‘crowdedness’andpressure Sees actions partly in terms of long-term goals or a wider conceptual framework Followsstandardisedandroutinisedprocedures Theexpertpractitioner: Nolongerreliesexplicitlyonrules,guidelinesandmaxims Hasanintuitivegraspofsituationsbasedondeep,tacitunderstanding Usesanalyticapproachesonlyinnovelsituationsorwhenproblemsoccur Because of our training and experience, we are able to practice medicine without considering in great detail how we come to make clinical decisions. Manyexpertandhighlycompetentclinicianshavenotstudiedtheprinciples outlined in this book. We believe, however, that learning the principles of clinicalproblemsolvingisimportantinordertoprovidethebestpossiblecare forourpatients,andthatunderstandingtheseprincipleswillbeincreasingly importantformedicalcareinthefuture. Firstly,understandingthemethodsforclinicalproblemsolvingisimportant whenaproblemariseswherewedonothavearoutineorpracticedapproach. By its nature, this happens more frequently in general practice than in any otherareaofmedicine.Itisprobablynoaccidentthatthethreeauthorsofthis book, and many authors who write in this area, come from general practice backgrounds.Butbeingabletodealwithnewandcomplexproblemsandbeing abletomanageuncertaintyisimportantinallareasofclinicalmedicine.Being able to understand the principles of clinical problem solving is particularly importantwhenwearerelativelyjuniorandhavenotyetdevelopedenough clinicalexperiencetoactmoreintuitively. Secondly, understanding these principles gives us a framework for incor- porating both new evidence and the values of our patients into our clinical decisions.Evidence-basedmedicineisdescribedas‘theintegrationofbestre- searchevidencewithclinicalexpertiseandpatientvalues’1,butitisnotalways cleartoclinicianshowthisintegrationmightoccur.Twochangesmakeitim- perativetofindmethodsforsuchintegration.Thefirstistherateatwhichnew medicalknowledgeisadvancing.Thesecondisthegreaterdesireforpatients to participate in decisions about their own health care. As another leader of Principlesofclinicalproblemsolving 3 the evidence-based medicine movement described it: ‘medicine is indeed in the middle of an intellectual revolution. Methods of reasoning and problem solving that might have worked well in the past are not sufficient to handle today’sproblems.’5 Theframeworkoutlinedinthisbookshowshowthein- tegrationbetweenclinicalexpertise,researchevidenceandpatientvaluescan begintooccur. Thirdly, there are times when we can predict that intuitive or routine de- cisionmakingmightfail.Beingawareofthepotentialcognitivebiasesinour routinethinkingcanhelpustobebetterandsaferdoctors. Finally, we have found that learning and thinking about the principles of clinicalproblemsolvinghasimprovedourunderstandingofwhatwearedoing as clinicians. All three of us have found that understanding these principles makesourclinicalworkmorefun. The framework for clinical problem solving Studiesofnaturalisticdecisionmakinghaveshownthatexpertsmakingcrit- icaldecisions,suchasfirecommandersinchargeofunitsfightinglargefires, areoftenunawareofmakinganydecisions.6Thisiseventhoughtheyclearly have to make decisions such as the need for extra units, when to withdraw firefightersfromasituationandsoon.Whenaskedtoexplaintheirdecision- makingprocess,thefirecommanderswillusuallyinsistthattheydonotmake decisionsandthatitisobviouswhattodoinanygivensituation.Afteranalysis ofhowtheyactuallymadecriticaldecisions,itseemsthatexpertsusetheirex- periencetomatcheachnewsituationtoaprototype,andtousethisprototype todecideonacourseofaction.Theymayrecognisethattheyneedtocollect moredatatoclarifyasituationortore-evaluateasituationifconditionschange over time, but at each point they are trying to match the situation to a pro- totype.Themainelementsoftherecognitionprimeddecision-makingmodel areshowninFigure1.1.Thismodelappearstobeveryconsistentwithwhat weknowabouthowexpertcliniciansmakedecisionsinmedicine(Box1.3).7 For example, when a patient is admitted with a myocardial infarction, it is importanttodecidequicklywhetherapatientshouldhavethrombolyticther- apy or not. There are many factors that could determine this choice, but it hasbeenshown,infact,thatdoctorsuseonlyafewofthesefeaturestomake thedecision.Doctorsareoftenbetterthanclinicalalgorithmsordecisionsup- port systems could be at determining when the clinical pattern does not fit. For example, a case report in The Lancet describes a patient who presented withchestpainandSTsegmentelevationintheanteriorleads.8 Themedical team was preparing to give the patient thrombolytic therapy, when the pa- tientremarkedthathecouldnotmoveorfeelhislegs.Recognisingthatthis didnotfittheclinicalpatternofmyocardialinfarction,theteaminvestigated further. A CT of the patient’s chest and abdomen showed a thoracic aortic dissection.
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