Epidemiology - definition, scope and uses.ppt

All Credit goes to Dr. Bishnu P Chaulagai

2. Definitions of epidemiology
8/1/2022Dr. Bishnu Choulagai2
Thescopeofepidemiologyhasenlargedoveryears
Thedefinitionofepidemiologyhasalsochangedfrom
narrowtomodernconcept,i.e.,
•‘Thebranchofmedicalsciencedealingwithepidemics’
(Parkin,1873)
•‘Thescienceofthemassphenomenaofinfectious
diseases’(Frost,1927)
•‘Thestudyofdisease,anydisease,asamass
phenomenon’(Greenwood,1934)
•‘Thestudyofthedistributionanddeterminantsof
diseasefrequencyinman’(MacMohan,1960)

3. Definition
8/1/2022Dr. Bishnu Choulagai3
“EpidemiologyisthestudyoftheDistribution
anddeterminantsofHealthRelatedstatesor
eventsinSpecifiedPopulations,andthe
applicationofthisstudytothepreventionand
controlofhealthproblems.”
(Last JM, Dictionary of Epidemiology, 1988:42).

4. Epidemiology….
8/1/2022Dr. Bishnu Choulagai4
1)Study.Epidemiologyisascientificdiscipline-a
fundamentalscienceofpublichealth.Ithas,atits
foundation,soundmethodsofscientificinquiry.
Examplesofstudiesincludeobservational,
analyticalorexperimental.
2)Distribution.Frequencyandpatternofhealth
eventsinapopulation.Frequencyincludesnotonly
thenumberofsucheventsinapopulation,butalso
therateorriskofdiseaseinthepopulation.
Distributionbytime,personandplacecouldbe
studied.

5. Epidemiology…
8/1/2022Dr. Bishnu Choulagai5
3)Determinants.Epidemiologyisalsousedto
searchforcausesandotherfactorsthat
influencetheoccurrenceofhealth-related
events.
informationonassociatedfactorsbycomparing
groupswithdifferentratesofdiseaseoccurrence.
Identifydemographiccharacteristics,genetic,
immunology,behaviors,environmentalexposures,
andotherpotentialfactorsassociatedwithhealth
outcomes.Epidemiologicfindingsprovideevidence
toorganizeeffectivepublichealthmeasures(health
promotion,diseasepreventionandcontrol)

6. Epidemiology…
8/1/2022Dr. Bishnu Choulagai6
4)Health-relatedstatesorevents.Originally,
epidemiologywasconcernedwithepidemicsof
communicablediseases.Thenepidemiologywas
extendedtoendemiccommunicablediseasesand
non-communicablediseases.
Morerecently,epidemiologicmethodshavebeen
appliedtochronicdiseases,injuries,birthdefects,
maternalandchildhealth,occupationalhealthand
environmentalhealth.
Now,evenbehaviorsrelatedtohealthand
wellbeing(example:amountofexercise,seatbelt
use)arestudiedusingepidemiologicmethods.

7. Epidemiology…
8/1/2022Dr. Bishnu Choulagai7
5)Specifiedpopulations.Epidemiologystudies
populationgroupswithidentifiablecharacteristics
suchasoccupationalgroups.

8. Epidemiology…
8/1/2022Dr. Bishnu Choulagai8
6)Application.Asadisciplinewithinpublic
health,epidemiologyprovidesdatafordirecting
publichealthaction.Epidemiologicalstudies
provideevidencesthatareusefulinpromoting
andprotectinghealthandcontrollinghealth
problems.

9. Goals of Epidemiology
8/1/2022Dr. Bishnu Choulagai9
Toeliminateorreducethehealthproblemsor
itsconsequences
Topromotethehealthandwellbeingofthe
societyasawhole

10. Aims of Epidemiology
8/1/2022Dr. Bishnu Choulagai10
describe,explain,predictandcontrol
Describethehealthstatusofpopulation–
enumeratethecases,obtainrelativefrequencies
ofthediseasewithinsubgroupsandtodiscover
trendsinoccurrenceofdisease
Explainetiologyofdisease–discovercausal
factors
Predicttheoccurrenceofdisease–estimate
numberofcasesthatwilldevelop,identify
distributionwithinpopulations
Controlthedistributionofdisease–prevent
occurrenceofnewcases,treatexistingcases
andprolonglifeofthosewiththedisease

11. Scope and uses of epidemiology
Studyingcausationofdisease:Genetic,behavioral
andenvironmentalcauses
Courseandoutcomeofdisease(naturalhistoryof
disease):Howadiseaseprogressesthrough
subclinicalchanges,clinicaldiseaseandrecovery,
disabilityordeath
Describinghealthstatusofpopulations:Describingthe
burdenofdiseasesothatlimitedresourcescouldbe
usedinbestpossibleways.
Evaluatinginterventions:Interventionsincludehealth
promotion,preventivemeasures,treatmentand
behaviorchange.Theseinterventionsaimatreducing
illhealthinpopulationsandthusimprovingpublic
health.
8/1/2022Dr. Bishnu Choulagai11

12. Epidemiologystudiesspecificpopulation
selectedfromaspecificareaataspecifictime.
Example–patientsworkinginafactoryor
childrenhavingpneumoniainacertain
community.Thespecificpopulationformbasefor
definingsubgroups(education,age,ethnicityetc)
Epidemiologyisconcernednotonlywithdeath,
illnessanddisabilitybutalsowithbehaviors
affectinghealth
Scope and uses of epidemiology
8/1/2022Dr. Bishnu Choulagai12

13. Methodology of epidemiological study
Definitionoftheproblem,suchasrelationshipof
outcomeandexposure
Statementofexistingfactorsbytabulatingall
availableinformationasperage,sex,class,etc.
Formulationofhypothesis,e.g.smoking
increasesriskofcancer
Testingofhypothesisbymakingobservations,
trialsorinvestigations
Statisticalanalysisanddrawingoflogical
conclusions
8/1/2022Dr. Bishnu Choulagai13

14. Agent, host and environment
Global,regionalandnationalcontext
Preventionandcontrolprogramsand
status
Nationalpolicyandstrategies
Targetsandachievement
Criticalreflections
Applied epidemiology
1. Presentation and discussion
8/1/2022Dr. Bishnu Choulagai14

15. Understandorganizationandcontentof
paperspublishedinjournals
Developprotocolforcarryingoutan
epidemiologicalstudy
Updateadvancesinepidemiological
conceptsandmethods
2.Criticalappraisalofscientificpapers
andapplicationofepidemiological
methodstostudyhealthproblems
8/1/2022Dr. Bishnu Choulagai15

16. 3.Analyzedatasettocalculate
epidemiologicalindices
4.Studyoforganizationofhealth
servicesforvarioushealthproblems
8/1/2022Dr. Bishnu Choulagai16

17. Thanks
8/1/2022Dr. Bishnu Choulagai17