Therearemanygoodepidemiologytextbooksonthemarket,butmostoftheseare addressedtostudentsofpublichealthorpeoplewhodoclinicalresearchwithe- demiologicmethods. Thereisaneedforashortintroductiononhowepidemiologic methodsareusedinpublichealth,geneticandclinicalepidemiology,becausehealth professionalsneedtoknowbasicepidemiologicmethodscoveringetiologicaswell asprognosticfactorsofdiseases. Theyneedtoknowmoreaboutmethodologythan introductorytextsonpublichealthhavetooffer. Insomehealthfaculties,epidemiologyisnotevenpartoftheteachingcurri- lum. Webelievethistobeaseriousmistake. Medicalstudentsarestudentsofall aspectsofdiseasesandhealth. Withoutknowingsomethingaboutepidemiologythe cliniciansandotherhealthprofessionalscannotreadagrowingpartofthesci- ti cliteratureinanyreasonablycriticalwayandcannotnavigateintheworldof "evidence-basedmedicineandevidence-basedprevention. "Withoutskillsine- demiologicmethodologytheyareinthehandsofexpertsthatmaynotonlyhavean interestinhealth. Some health professionals may believe that only common sense is needed to conductepidemiologicalstudies,butthescienti cliteratureandthepublicdebate onhealthissuesindicatethatcommonsenseisofteninshortsupplyandmaynot thrivewithoutsomeformaltraining. Epidemiologic methods play a key role in identifying environmental, social, and genetic determinants of diseases. Clinical epidemiology addresses the tr- sitionfromdiseasetohealthortowardmortalityorsocialormedicalhandicaps. Publichealthepidemiologyaddressesthetransitionfrombeinghealthytobeingnot healthy. Descriptiveepidemiologyprovidesthediseasepatternthatisneededtolook athealthinabroadperspectiveandtosettheprioritiesright. Epidemiologyisabasic scienceofmedicinewhichaddresseskeyquestionssuchas"Whobecomesill?"and "Whatareimportantprognosticfactors?"Answerstosuchquestionsprovidethe basisforbetterpreventionandtreatmentofdiseases. Many people contributed to the writing of this book: medical students in Denmark,studentsofepidemiologyattheIEAEEPEsummercourseinFlorence, Italy,andstudentsofpublichealthinLosAngeles. Withouttechnicalassistance v vi Preface fromGitteNielsen,JenadeShelley,NinaHoheandPamMasangkaythebookwould neverhavematerialized. LosAngeles,California JornOlsen Odense,Denmark KaareChristensen IowaCity,Iowa JeffMurray Stockholm,Sweden AndersEkbom Contents Part I Descriptive Epidemiology 1 Measures of Disease Occurrence ...3 IncidenceandPrevalence ...4 Incidence...6 RatesandDynamicPopulations ...7 CalculatingObservationTime...9 Prevalence,Incidence,Duration ...10 MortalityandLifeExpectancy ...11 LifeExpectancy ...12 References...13 2 Estimates of Associations ...15 3 Age Standardization...19 4 Causes of Diseases ...23 References...28 5 Descriptive Epidemiology in Public Health...29 GraphicalModelsofCausalLinks ...33 References...35 6 Descriptive Epidemiology in Genetic Epidemiology...37 OccurrenceDatainGeneticEpidemiology ...37 ClusteringofTraitsandDiseasesinFamilies ...38 TheOccurrenceofGeneticDiseases ...40 References...41 7 Descriptive Epidemiology in Clinical Epidemiology...43 SuddenInfantDeathSyndrome(SIDS)...44 CytologicalScreeningforCervixCancer ...45 ChangesinTreatmentofJuvenileDiabetes ...46 References...47 vii viii Contents Part II Analytical Epidemiology 8 Design Options...51 CommonDesignsUsedtoEstimateAssociations...51 EcologicalStudy ...52 Case-ControlStudy...54 CohortStudy ...5 5 ExperimentalStudy ...56 Reference ...57 9 Follow-Up Studies ...59 TheNon-experimentalFollow-Up(Cohort)Study ...59 StudyingRiskasaFunctionofBMI ...60 LongitudinalExposureData...62 DifferentTypesofCohortorFollow-UpStudies...63 10 Case-Control Studies...67 Case-CohortSampling ...69 DensitySamplingofControls...69 Case-Non-caseStudy...71 PatientControls ...72 SecondaryIdenti cationoftheSourcePopulation ...74 Case-ControlStudiesUsingPrevalentCases...74 WhentoDoaCase-ControlStudy? ...77 References...78 11 The Cross-Sectional Study...79 12 The Randomized Controlled Trial (RCT) ...81 Reference ...

Therearemanygoodepidemiologytextbooksonthemarket,butmostoftheseare addressedtostudentsofpublichealthorpeoplewhodoclinicalresearchwithe- demiologicmethods. Thereisaneedforashortintroductiononhowepidemiologic methodsareusedinpublichealth,geneticandclinicalepidemiology,becausehealth professionalsneedtoknowbasicepidemiologicmethodscoveringetiologicaswell asprognosticfactorsofdiseases. Theyneedtoknowmoreaboutmethodologythan introductorytextsonpublichealthhavetooffer. Insomehealthfaculties,epidemiologyisnotevenpartoftheteachingcurri- lum. Webelievethistobeaseriousmistake. Medicalstudentsarestudentsofall aspectsofdiseasesandhealth. Withoutknowingsomethingaboutepidemiologythe cliniciansandotherhealthprofessionalscannotreadagrowingpartofthesci- ti cliteratureinanyreasonablycriticalwayandcannotnavigateintheworldof "evidence-basedmedicineandevidence-basedprevention. "Withoutskillsine- demiologicmethodologytheyareinthehandsofexpertsthatmaynotonlyhavean interestinhealth. Some health professionals may believe that only common sense is needed to conductepidemiologicalstudies,butthescienti cliteratureandthepublicdebate onhealthissuesindicatethatcommonsenseisofteninshortsupplyandmaynot thrivewithoutsomeformaltraining. Epidemiologic methods play a key role in identifying environmental, social, and genetic determinants of diseases. Clinical epidemiology addresses the tr- sitionfromdiseasetohealthortowardmortalityorsocialormedicalhandicaps. Publichealthepidemiologyaddressesthetransitionfrombeinghealthytobeingnot healthy. Descriptiveepidemiologyprovidesthediseasepatternthatisneededtolook athealthinabroadperspectiveandtosettheprioritiesright. Epidemiologyisabasic scienceofmedicinewhichaddresseskeyquestionssuchas"Whobecomesill?"and "Whatareimportantprognosticfactors?"Answerstosuchquestionsprovidethe basisforbetterpreventionandtreatmentofdiseases. Many people contributed to the writing of this book: medical students in Denmark,studentsofepidemiologyattheIEAEEPEsummercourseinFlorence, Italy,andstudentsofpublichealthinLosAngeles. Withouttechnicalassistance v vi Preface fromGitteNielsen,JenadeShelley,NinaHoheandPamMasangkaythebookwould neverhavematerialized. LosAngeles,California JornOlsen Odense,Denmark KaareChristensen IowaCity,Iowa JeffMurray Stockholm,Sweden AndersEkbom Contents Part I Descriptive Epidemiology 1 Measures of Disease Occurrence ...3 IncidenceandPrevalence ...4 Incidence...6 RatesandDynamicPopulations ...7 CalculatingObservationTime...9 Prevalence,Incidence,Duration ...10 MortalityandLifeExpectancy ...11 LifeExpectancy ...12 References...13 2 Estimates of Associations ...15 3 Age Standardization...19 4 Causes of Diseases ...23 References...28 5 Descriptive Epidemiology in Public Health...29 GraphicalModelsofCausalLinks ...33 References...35 6 Descriptive Epidemiology in Genetic Epidemiology...37 OccurrenceDatainGeneticEpidemiology ...37 ClusteringofTraitsandDiseasesinFamilies ...38 TheOccurrenceofGeneticDiseases ...40 References...41 7 Descriptive Epidemiology in Clinical Epidemiology...43 SuddenInfantDeathSyndrome(SIDS)...44 CytologicalScreeningforCervixCancer ...45 ChangesinTreatmentofJuvenileDiabetes ...46 References...47 vii viii Contents Part II Analytical Epidemiology 8 Design Options...51 CommonDesignsUsedtoEstimateAssociations...51 EcologicalStudy ...52 Case-ControlStudy...54 CohortStudy ...5 5 ExperimentalStudy ...56 Reference ...57 9 Follow-Up Studies ...59 TheNon-experimentalFollow-Up(Cohort)Study ...59 StudyingRiskasaFunctionofBMI ...60 LongitudinalExposureData...62 DifferentTypesofCohortorFollow-UpStudies...63 10 Case-Control Studies...67 Case-CohortSampling ...69 DensitySamplingofControls...69 Case-Non-caseStudy...71 PatientControls ...72 SecondaryIdenti cationoftheSourcePopulation ...74 Case-ControlStudiesUsingPrevalentCases...74 WhentoDoaCase-ControlStudy? ...77 References...78 11 The Cross-Sectional Study...79 12 The Randomized Controlled Trial (RCT) ...81 Reference ...

This book marks the 50th anniversary of the foundation of the International Epidemiological Association (IEA). It is a unique compendium by the world's leading epidemiologists of how the field has developed, and how it can be (and has been) applied to the control of common conditions and threats to public health. Five distinct sections guide the reader through the wealth of material: * Gives an historical account of the concepts and ideas, and current importance of epidemiology to global health issues and to organisations such as the WHO. * Illustrates the advances and contributions to epidemiologic knowledge and the control of disease in specific areas such as cancer, cardiovascular disease, respiratory disease, tuberculosis, maternal and child health, non-biologic disorders such as war and disasters, and new infectious diseases. * Outlines the use of epidemiology in areas such as public health, health services, occupational and environmental medicine, social epidemiology and nutrition. * Discusses methodological developments such as statistics, information sources, investigation of disease outbreaks and clinical epidemiology. * Looks at how the subject has developed internationally, with perspectives on regions such as the Americas, Poland, Spain, Eastern Mediterranean, New Zealand, China, Thailand and Japan. This remarkable insight into how epidemiology has developed is essential reading for both existing and aspiring epidemiologists.