流行病学英文总结

流行病学英文版总结（精华版）乌衣月1EpidemiologyEpidemiologyisthestudythatisbasedondistributionandfactorsofdiseasesandhealth-relatedstatesinpopulations,andthenmakespoliticiesandtakesmeasurestocontrolheslthproblems.2ExposureExposureisaverycommonusedterminepidemiology,itreferstothecausalfactorsthatmaybeassociatedwiththedisease,forexample,contactwithaharmfulmaterials,orsomecharacteristics,suchastheagewhichmayputanindividualatincreasedrisk.3OutcomeOutcomeisthediseaseorotherchangesinhealthstatus.Itisthepossibleresultthatmaybeassociatedwiththecauses,riskfactorsorpreventivemeasures.4DescriptiveepidemiologyDescriptiveepidemiologyisconcernedwiththevariationsofmorbidityandmortalityinacommunity.Itconcentratesonthedescriptionofdistributionofmorbidityormortalitybyperson,placeandtime,andthenwecanposethehyposthesis,suchascasereport,ecologicalstudyandcross-sectionalstudy.5EcologicalstudyEcologicalstudyisatypeofdescriptivestudy.Itisthestudyoftherelationshipbetweensomefactorsanddiseasesinthegrouplevel,theunitofobservationandanalysisisgroup.Wedescribetheexposurestatusofdiseasefactorsandthefrequencyofdiseasesindifferentpopulationsandthenanalysetherelationshipbetweenexposureanddisease,forexample,ecologicalcomparisonstudyandecologicaltrendstudy.6ExperimentalepidemiologyExperimentalepidemiologyistoidentifyagroupofsubjectswiththesameconditions,andrandomizesthesubjectsintointerventionandcontrolgroups,followsthemupforaperiodoftime,comparestheoutcomebetweenthegroups,soastoevaluatetheefficacyoftheintervention.Itisalsocalledtheinterventionalstudy,includesclinicaltrial,fieldtrialandcommunitytrial.7ObservationalstudyObservationalstudyisakindofepidemiology.Weobserveandmeasuretheoccurrenceofthediseaseorotherhealth-relatedstatusindifferentgroupswithvariouscharacteristicsandattempttoidentythecausalassociationbetweentheexposureandoutcome,butwedonotinterveneinanyway,soitiscalledtheobservationalstudy,suchascross-sectionalstudy,cohortstudyandsoon.8ThreelevelsofpreventionPrimarypreventionconcentratesonthecausepreventionorreductionofriskfactors,soastopreventthedevelopmentofdisease.Secondarypreventionistodiagnoseandtreatdiseasesintheirearlystagessoastorestoreorimprovehealth,suchasthescreeningprogram.Tertiarypreventionistoreducecomplicationsofdisease,improvetheoutcome,soastoimprovethequalityoflifeofthepatients.9PYLLPYLLismeasureofthesocio-economicimpactoftheprematuredeathofanindividual.Itismeasuredbydeductingtheageofdeathfromthelifeexpectancyoftheindividual.10IncidenceIncidencemeasurestherateofoccurrenceofnewcasesofdiseaseinagivenpopulationinagiventimeandcanbeusedtodescribetheriskofdiseaseinthatpopulation.(numberofnewcases/population)10PrevalencePrevalencemeasurestherateofoccurrenceofbothnewandongoingcasesofdiseasesinagivenpopulation,inagiventime,andcanbeusedtodescribetheburdenofdiseaseinthatpopulation,includespointprevalenceandperiodprevalence.(numberofexistingcases/populationatrisk)11Cross-sectionalstudyCross-sectionalstudyisatypeofdescriptivestudy,isalsocalledprevalencestudy.Itisaninvestigationthatsystematicallycollectsinformationinagiventimeanddoesnotuseintervention.Itconcentratesondescriptionofthedistributionofprevalenceratebyperson,place,andtime,andthenwecanposethehyposthesis.12BiasBiasisasystematicerror,itexsitsinthedesign,conductoranalysisofastudyanditmayresultinamistakenestimateoftheassociationbetweentheexposureandoutcome,suchasselectionbias,informationbias,confoundingbias.13ConfoundingbiasConfoundingvariableisanextraneousfactorthatrelates(positivelyornegatively)withboththeoutcomeandthetentativefactorofstudy,andmayresultinamistakenestimateofanexposureeffectontheriskofdisease.Andthebiaswhichiscausedbytheconfoundingvariableiscalledconfoundingbias.14ScreeningScreeningistheearlydetectionandpresumptiveidentificationofanunrecognizeddiseaseordeficitbyapplicationofexaminationsortestswhichcanbeappliedrapidlyandcheaplytolargepopulations.15CohortstudyCohortstudyisakindofobservationalstudy.Theinvestigatorselectsagroupofexposedindividualsandagroup(orgroups)ofnon-exposedindividuals,andfollowsupbothgroupsforaperiodoftime,tocomparetheincidenceofdiseaseorthedeathrateofthediseaseinthetwogroups(ormoregroups)andmeasuretheassociationbetweentheexposureandtheoutcome.Itisalsocalledaprospectivestudyorfollow-upstudy.16Case-controlstudiesCase-controlstudiesstartwiththeidentificationofpeoplewiththediseaseofinterstandacontrolgroupofpeoplewithoutthisdisease,thencollectsomeinformationoftheexposureinbothgroups,andmeasuretheassociationbetweentheexposureandthediseasebycomparingthediseasedandnon-diseasedgroup.Itisakindofobservationalstudy,anditisalsocalledtheretrospectivestudy.17MatchingMatchingisdefinedastheprocessofmakingastudygroupandacomparisongroupcomparablewithrespecttocertaincharacteristics,suchassex,age,raceandsoon.Thepueposeofmatchingistoreducethelikelihoodofconfounding,includesindividualmatchingandfrequencymatching.18ORORisaveryusefulmeasurefortheassociationbetweenexposureandoutcome.Itistheratiooftheoddsofexposureamongthecasestotheoddsofexposureamongthecontrols.Themoretheordepartsfr