Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 Case-ControlStudies Thecase-controlapproachisapowerfulmethodforinvestigatingfactorsthatmay explainaparticularevent.Itisextensivelyusedinepidemiologytostudydisease incidence,oneofthebest-knownexamplesbeingtheinvestigationbyBradfordHill andDollofthepossibleconnectionbetweencigarettesmokingandlungcancer.More recently,case-controlstudieshavebeenincreasinglyusedinotherfields,including sociologyandeconometrics. Withaparticularfocusonstatisticalanalysis,thisbookisidealforappliedand theoreticalstatisticianswantinganup-to-dateintroductiontothefield.Itcoversthe fundamentalsofcase-controlstudydesignandanalysisaswellasmorerecent developments,includingtwo-stagestudies,case-onlystudiesandmethodsfor case-controlsamplingintime.Thelatterhaveimportantapplicationsinlarge prospectivecohortsthatrequirecase-controlsamplingdesignstomakeefficientuseof resources.Moretheoreticalbackgroundisprovidedinanappendixforthosenewto thefield. ruth h. keoghisaLecturerintheDepartmentofMedicalStatisticsattheLondon SchoolofHygieneandTropicalMedicine. d. r. coxisoneoftheworld’spre-eminentstatisticians.Hisworkontheproportional hazardsregressionmodelisoneofthemost-citedandmostinfluentialpapersin modernstatistics.In2010hewontheCopleyMedaloftheRoyalSociety‘forhis seminalcontributionstothetheoryandapplicationofstatistics’.Heiscurrentlyan HonoraryFellowatNuffieldCollege,Oxford. Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 INSTITUTE OF MATHEMATICAL STATISTICS MONOGRAPHS EditorialBoard D.R.Cox(UniversityofOxford) A.Agresti(UniversityofFlorida) B.Hambly(UniversityofOxford) S.Holmes(StanfordUniversity) X.-L.Meng(HarvardUniversity) IMSMonographsareconciseresearchmonographsofhighqualityonanybranchof statistics or probability of sufficient interest to warrant publication as books. Some concern relatively traditional topics in need of up-to-date assessment. Others are on emergingthemes.Inallcasestheobjectiveistoprovideabalancedviewofthefield. Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 Case-Control Studies RUTH H. KEOGH LondonSchoolofHygiene andTropicalMedicine D. R. COX UniversityofOxford Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 UniversityPrintingHouse,CambridgeCB28BS,UnitedKingdom PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork CambridgeUniversityPressisapartoftheUniversityofCambridge. ItfurtherstheUniversity’smissionbydisseminatingknowledgeinthepursuitof education,learningandresearchatthehighestinternationallevelsofexcellence. www.cambridge.org Informationonthistitle:www.cambridge.org/9781107019560 (cid:2)C RuthH.KeoghandD.R.Cox2014 Thispublicationisincopyright.Subjecttostatutoryexception andtotheprovisionsofrelevantcollectivelicensingagreements, noreproductionofanypartmaytakeplacewithoutthewritten permissionofCambridgeUniversityPress. Firstpublished2014 PrintedintheUnitedKingdombyMPGPrintgroupLtd,Cambridge AcataloguerecordforthispublicationisavailablefromtheBritishLibrary LibraryofCongressCataloguinginPublicationdata ISBN978-1-107-01956-0Hardback CambridgeUniversityPresshasnoresponsibilityforthepersistenceoraccuracyof URLsforexternalorthird-partyinternetwebsitesreferredtointhispublication, anddoesnotguaranteethatanycontentonsuchwebsitesis,orwillremain, accurateorappropriate. Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 Contents Preface ix Preamble 1 Notes 7 1 Introductiontocase-controlstudies 8 1.1 Definingacase-controlstudy 8 1.2 Measuringassociation:theoddsratio 12 1.3 Methodsforcontrollingconfounding 13 1.4 Temporalaspects 16 1.5 Furtherdetailsonthesamplingofcasesandcontrols 20 1.6 Biasincase-controlstudies 23 1.7 Useofcase-controlstudies 26 Notes 29 2 Thesimplestsituation 31 2.1 Preliminaries 31 2.2 Measuringassociation 34 2.3 Statisticalanalysis 36 2.4 Modelformulation 42 2.5 Designimplicationsfornumbersofcasesandcontrols 44 2.6 Logisticdependence 45 2.7 Explanatoryvariablewithmorethantwolevels 47 2.8 Conditionaloddsratios:combiningestimates 48 2.9 Aspecialfeatureofoddsratios 51 2.10 Introducingtime 54 2.11 Causalityandcase-controlstudies 57 Notes 59 3 Matchedcase-controlstudies 62 3.1 Preliminaries 62 3.2 Choiceofmatchedcontrols 63 v Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 vi Contents 3.3 Analysisofmatcheddata 65 3.4 Discussion 70 3.5 Alternativeanalysesofmatcheddata 71 3.6 Overmatching 73 3.7 Furthertheoreticalpoints 75 3.8 Generalizations:severalcontrolspercase 76 3.9 Logisticdependence 78 3.10 Introducingtime 80 Notes 81 4 Ageneralformulation 83 4.1 Preliminaries 83 4.2 Logisticregressionforcase-controlstudies 84 4.3 Extensions 89 4.4 Moreonnon-collapsibility 93 4.5 Non-logisticmodels 97 4.6 Statisticalefficiency 99 4.7 Estimatingotherquantities 102 4.8 Useofthedistributionofexposure 104 4.9 Beyondcase-controlstudies:amoregeneralview 105 Notes 108 5 Case-controlstudieswithmorethantwooutcomes 111 5.1 Preliminaries 111 5.2 Polychotomouscase-controlstudies 111 5.3 Polychotomousstudieswithmatching 117 5.4 Morethanonecontrolgroup 119 5.5 Orderedoutcomegroups 120 5.6 Case-onlystudies 122 Notes 130 6 Specialsamplingdesigns 132 6.1 Preliminaries 132 6.2 Two-stagesamplingdesign 133 6.3 Likelihoodanalysesfortwo-stagestudies 143 6.4 Discussion 148 6.5 Specialsamplinginmatchedcase-controlstudies 150 6.6 Case-controlstudiesusingfamilymembers 152 6.7 Augmentingcase-controldatausingfamilymembers 155 Notes 157 7 Nestedcase-controlstudies 160 7.1 Preliminaries 160 7.2 Thenestedcase-controldesign 162 Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 Contents vii 7.3 Analysisofnestedcase-controlstudies 165 7.4 Furthercommentsonanalysis 167 7.5 Someextensions 169 7.6 Moreelaboratesamplingprocedures 170 7.7 Furthercommentsonthesamplingofcontrols 175 7.8 Somealternativemodels 176 7.9 Extendeduseofcontrols 180 7.10 Estimatingabsoluterisk 182 7.11 Usingfull-cohortinformation 184 Notes 186 8 Case-subcohortstudies 191 8.1 Preliminaries 191 8.2 Essentialoutlineofthecase-subcohortdesign 193 8.3 Analysisdisregardingtime 194 8.4 Case-subcohortstudyusingeventtimes 198 8.5 Sizeofthesubcohort 202 8.6 Stratifiedcase-subcohortstudies 204 8.7 Somefurtherapproaches 207 8.8 Comparisonbetweennestedcase-controland case-subcohortstudies 208 Notes 209 9 Misclassificationandmeasurementerror 212 9.1 Preliminaries 212 9.2 Misclassificationinanexposurevariable 214 9.3 Misclassificationofcasesandcontrols 218 9.4 Misclassificationinmatchedcase-controlstudies 220 9.5 Errorincontinuousexposures 221 9.6 Correctingforerrorinacontinuousexposure 228 Notes 236 10 Synthesisofstudies 240 10.1 Preliminaries 240 10.2 Somelarge-samplemethods 241 10.3 Graphicalrepresentation 243 10.4 Studyhomogeneity 244 10.5 Anexactanalysis 248 10.6 Combiningstudiesofdifferenttype 250 Notes 250 Appendix Atheoreticaldiversion 252 A.1 Preliminaries 252 A.2 Multidimensionalparameter 253 Trim: 228mm×152mm Top: 10.193mm Gutter: 18.98mm CUUK2556-FM CUUK2556-Keogh 9781107019560 October7,2013 14:40 viii Contents A.3 Themaximum-likelihoodestimate 254 A.4 Significancetests 256 A.5 Moredetailedtheory 256 A.6 Pseudo-likelihood 256 A.7 Weightedestimation 258 A.8 Bayesiananalysis 258 Notes 261 References 262 Index 281