Essential Evidence-based Medicine, Second Edition - nogracias.eu

457 Pages·2010·2.59 MB·English

by  Dan Mayer

EssentialEvidence-BasedMedicine
SecondEdition

Essential
Evidence-Based
Medicine
Second Edition
Dan Mayer, MD
cambridge university press
Cambridge,NewYork,Melbourne,Madrid,CapeTown,Singapore,Sa˜oPaulo,Delhi
CambridgeUniversityPress
TheEdinburghBuilding,CambridgeCB28RU,UK
PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork
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Informationonthistitle:www.cambridge.org/9780521712415
Firstedition(cid:2)c D.Mayer2004
Secondedition(cid:2)c D.Mayer2010
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Firstpublished2010
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Mayer,Dan.
Essentialevidence-basedmedicine/DanMayer.–2nded.
p.; cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-521-71241-5(pbk.)
1.Evidence-BasedMedicine. I.Title.
[DNLM:1.Evidence-BasedMedicine. WB102.5M4682010]
R723.7.M396 2010
616–dc22 2009024641
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Contents
Listofcontributors pagevii
Preface ix
ForewordbySirMuirGray xi
Acknowledgments xiii
1 Abriefhistoryofmedicineandstatistics 1
2 Whatisevidence-basedmedicine? 9
3 Causation 19
4 Themedicalliterature:anoverview 24
5 Searchingthemedicalliterature 33
SandiPirozzoandElizabethIrish
6 Studydesignandstrengthofevidence 56
7 Instrumentsandmeasurements:precisionandvalidity 67
8 Sourcesofbias 80
9 Reviewofbasicstatistics 93
10 Hypothesistesting 109
11 TypeIerrorsandnumberneededtotreat 120
12 NegativestudiesandTypeIIerrors 130
13 Riskassessment 141
14 Adjustmentandmultivariateanalysis 156
15 Randomizedclinicaltrials 164
16 Scientificintegrityandtheresponsibleconductofresearch 179
JohnE.Kaplan
v
vi Contents
17 Applicabilityandstrengthofevidence 187
18 Communicatingevidencetopatients 199
LauraJ.Zakowski,ShobhinaG.Chheda,ChristineS.Seibert
19 Criticalappraisalofqualitativeresearchstudies 208
StevenR.Simon
20 Anoverviewofdecisionmakinginmedicine 215
21 Sourcesoferrorintheclinicalencounter 233
22 Theuseofdiagnostictests 244
23 Utilityandcharacteristicsofdiagnostictests:likelihoodratios,
sensitivity,andspecificity 249
24 Bayes’theorem,predictivevalues,post-testprobabilities,and
intervallikelihoodratios 261
25 ComparingtestsandusingROCcurves 276
26 Incrementalgainandthethresholdapproachtodiagnostictesting 282
27 Sourcesofbiasandcriticalappraisalofstudiesofdiagnostictests 295
28 Screeningtests 310
29 Practiceguidelinesandclinicalpredictionrules 320
30 Decisionanalysisandquantifyingpatientvalues 333
31 Cost-effectivenessanalysis 350
32 Survivalanalysisandstudiesofprognosis 359
33 Meta-analysisandsystematicreviews 367
Appendix1 Levelsofevidenceandgradesofrecommendations 378
Appendix2 Overviewofcriticalappraisal 384
Appendix3 Commonlyusedstatisticaltests 387
Appendix4 Formulas 389
Appendix5 ProofofBayes’theorem 392
Appendix6 Usingbalancesheetstocalculatethresholds 394
Glossary 396
Bibliography 411
Index 425
Contributors
ShobhinaG.Chheda UniversityofWisconsinSchoolofMedicineandPublic
Health,Madison,Wisconsin,USA
ElizabethIrish AlbanyMedicalCollege,NewYork,USA
JohnE.Kaplan AlbanyMedicalCollege,NewYork,USA
SandiPirozzo UniversityofQueensland,Brisbane,Australia
ChristineS.Seibert UniversityofWisconsinSchoolofMedicineandPublic
Health,Madison,Wisconsin,USA
StevenR.Simon HarvardMedicalSchool,Boston,Massachusetts,USA
LauraJ.Zakowski UniversityofWisconsinSchoolofMedicineandPublic
Health,Madison,Wisconsin,USA
vii

Preface
In1992duringaperiodofinnovativerestructuringofthemedicalschoolcur-
riculumatAlbanyMedicalCollege,Dr.HenryPohl,thenAssociateDeanforAca-
demicAffairs,askedmetodevelopacoursetoteachstudentshowtobecome
lifelonglearnersandhowthehealth-caresystemworks.Thischargebecamethe
focusofanewlongitudinalrequired4-yearcourseinitiallycalledCCCS,orCom-
prehensiveCareCaseStudy.In2000,thenamewaschangedtoEvidence-Based
Medicine.
Duringthenext15years,aformidablecoursewasdeveloped.Itconcentrates
on teaching evidence-based medicine (EBM) and health-care systems opera-
tions to all medical students at Albany Medical College. The first syllabus was
basedonacourseincriticalappraisalofthemedicalliteratureintendedforinter-
nalmedicineresidentsatMichiganStateUniversity.Thiscorehasexpandedby
incorporatingmedicaldecisionmakingandinformatics.Thebasisfortheorga-
nizationofthebookliesintheconceptoftheeducationalprescriptionproposed
byW.ScottRichardson,M.D.
Thegoalofthetextistoallowthereader,whethermedicalstudent,resident,
allied health-care provider, or practicing physician, to become a critical con-
sumer of the medical literature. This textbook will teach you to read between
thelinesinaresearchstudyandapplythatinformationtoyourpatients.
For reasons I do not clearly understand, many physicians are “allergic” to
mathematics.It seems that even the simplest mathematicalcalculations drive
them to distraction. Medicine is mathematics. Although the math content in
thisbookisonaprettybasiclevel,mostdailyinteractionwithpatientsinvolves
someunderstandingofmathematicalprocesses.Wemaywanttodeterminehow
muchbetterthepatientsittinginourofficewilldowithaparticulardrug,orhow
tointerpretapatient’sconcernaboutanewfindingontheiryearlyphysical.Far
more commonly, we may need to interpret the information from the Internet
thatourpatientbroughtin.Eitherway,wearedealinginprobability.However,I
haveendeavoredtokeepthemathassimpleaspossible.
Thisbookdoesnotrequireaworkingknowledgeofstatisticaltesting.Themath
islimitedtosimplearithmetic,andahandheldcalculatoristheonlycomputing
ix