Notescourse‘Introductionanalytical
epidemiologyandpublichealth’
(HNH-28803)
Content
LearninggoalsHNH-28803 2
Notesweek1 3
1.1Associationandcausation 3
1.2Studydesignsinanalyticalepidemiology 4
1.3Internalandexternalvalidity 8
1.4Measuresofassociation 15
1.5Measuresofpublichealthimpact 19
1.6Individualorpopulation?Thepreventionparadox 24
1.7Measuresinanalyticalepidemiology 27
1.8Self-test 27
Summaryofthemoderator 28
Notesweek2 30
2.1Cohortstudy 30
2.2Casecontrolstudy 33
2.3Interventiontrial 38
2.4Riskfactornon-communicablediseases 42
2.5Instructionposterpresentation 49
Summaryofthemoderator 49
Notesweek3 51
3.1Diseasescreening 51
3.2Self-test 58
3.3Posterpresentation:peerreview 58
3.4Exercisestopractice 58
3.5Followgroupdiscussions 58
Summaryofthemoderator 58
AppendixI-Assignment1.7 59
1.7Measuresinanalyticalepidemiology 59
Introductionanalyticalepidemiologyandpublichealth(HNH-28803) 1
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Note:Allreadingchaptersinthissummaryarederivedfrom:
WebbC.&BainP.(2017).Essentialepidemiology:anintroductionforstudentsandhealth
professionals.CambridgeUniversityPress,3ndor4thedition.
WageningenUniversityandResearch(WUR).
Introductionanalyticalepidemiologyandpublichealth(HNH-28803) 2
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LearninggoalsHNH-28803
● Describethemainnutrition-relatedandotherriskfactorsofmajorcommunicableand
non-communicablediseases:
○ diabetesmellitus;
○ cancer;
○ cardiovasculardiseases;
○ mentalhealthdisordersinelderlypeople;
○ osteoporosis;
● Calculateandinterpretbasicmeasuresusedinepidemiologyandpublichealth,
including:
○ variousmeasuresofassociation,e.g.,IRR,IPR,RR,andOR;
○ (Population)attributableriskandfraction(PARandPAF);
● Explainbasicstudydesignsusedinepidemiologyandpublichealthandindicate
major(dis)advantagesofthevariousstudydesigns,including:
○ ecologicalstudy;
○ cross-sectionalstudy;
○ cohortstudy;
○ case-controlstudy;
○ randomizedcontrolledtrial;
● Explainselectionbias,informationbias,andconfounding;
● Explainthedifferencebetweeninternalandexternalvalidityofepidemiological
findingsandinterpretprecisionmeasures;
● Explainthedifferencebetweenpopulationandindividualpreventionstrategies,and
theroleofearlydetectioninprimaryprevention,andcalculatevariousmeasures
usedfordiseasescreening,includingsensitivity,specificity,anddiagnosticvalue.
Introductionanalyticalepidemiologyandpublichealth(HNH-28803) 3
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Notesweek1
1.1Associationandcausation
1.1aWebsite-Spuriouscorrelations
N/A
1.1bAssociationandcausation
Thee tiologystudiesthecausesandoriginsofdiseases.Whatcausesadisease?The
causesmostlydon’texistinisolation,butaremultifactorial.As ufficientcauseisa
(combinationof)factor(s)thatwillinevitablyleadtoadisease.Ac omponentcauseisa
factorthatcontributestowardsdiseasecausation,butcannotdoitalone(aids,poornutrition,
exposuretoinfection).Eliminationofacomponentcausewillnotfullyeradicatedisease.
Whenyoupreventonecomponentcause,notallsufficientcausesareblocked.An ecessary
causeisanycomponentcausethatisrequiredforthedevelopmentofthedisease
(exposuretoTBCbacteria).
Inpublichealthpractice,youusuallyneedtointerveneonmultipleriskfactors
simultaneously:so-called‘complexinterventions’.P reventionisonlypossibleforriskfactors
thatarec ausallyrelatedtothedisease.
Causeandeffect,whatcamefirst;thechickenortheegg?C ausemustprecedetheeffect
(absoluterequirement).Inepidemiology,wemostlydonotobservecauseandeffect,but
associationsbetweenexposureandoutcomes.Beforeyouthinkaboutacause,thinkabout
non-causalassociations.Non-causalassociationscanbeduetobias,confoundingor
becauseofanartefactduetochange.Therecouldalsobear eversecausation.Isa
diseasecausesbyariskfactor,orisariskfactortheconsequenceofthedisease?
Theroleoftimeisveryimportant.Duringlife,yougathermoreandmorecomponentcauses.
Atapointoftimeyouhaveacompletes ufficientcause,afterwhichad iseasewilloccur.
Thiscanbealongprocess,thereforethed iagnosiscanbeonamuchlaterpointoftime.
Theperiodbetweentheonsetofthediseaseandthediagnosisiscalledthelatencytime.
Theperiodbeforetheonsetofadiseaseiscalledtheinductiontime.Thiscanalreadystart
atpreconception(thinkabouttheroleofgenetics).Notethatnotallexposuresincreasethe
riskofadisease,somepreventit(likevaccinations).
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