05 m rowland population research2 - university college dublin m rowland population... · 2010. 8....
TRANSCRIPT
PopulationResearch
MarionRowlandMBPHD
Structureoftalks
Today
Somedefinitionsanddifferences
ClassicStudies
Amodernexampleofwhyweneedanunderstandingofepidemiology
Tomorrow
Studydesignandmethodology
VariousTerminologies
• PopulationHealth
• PublicHeath
• Epidemiology– Historically
• InfectiousDisease
• ChronicDisease
– ModernEpidemiology• ClinicalEpidemiology
• GeneticEpidemiology
ThePractitioners
Epidemiologist‐DollSusserSteinDawbar
Statistician‐HillMantelBerksonFisher
DefinitionofEpidemiology
Themainfunctionofepidemiologyistodiscovergroupsinthepopulationwithhighratesofdiseaseandwithlowratessothatthecauseofthediseasecanbepostulated
Morris1955
Epidemiologyisthestudyofcausality
Diseasedistributioninapopulation
Determinantsorriskfactorsofdisease
–Who–Why–When–How
Whatdowedo
ResearchMethodology
Person/patient/participant
Community/generalpopulation/clinicalsetting
Representativesampleandapplyfindingstothegeneralpopulation
DataSources
Publicallyavailabledatasets
Collectionofgroupspecificdata
LargeScalepopulationbasedstudies
IssuesinEpidemiology
CaseDefinitionDefinitionofSwineflu/avianflu/coldDefinitionofObesity/HypertensionDefinitionoflungcancer
WhoreportsSelfreportDoctorDiagnosedDefinitiveclinicaltest–Publicrecord
RegisterofdeathsCancerRegistriesNotifiablediseases
OnsetofDisease
Differentissuesindifferenttypesofdisease
InfectiousDiseaseChronicDisease/Cancer InductionPeriod
LatentPhaseofDiseaseDiagnosis
ScreeningClinicalDiagnosis
IncidentorPrevalentcases
OutcomeMeasure
Mortality
Bestoutcomemeasure
Morbidity
Somehardendpoint.
Measures
Statistics
Ratio
Percentage
Proportion
Probability
Definitions
Risk:Numberofpersonswhodevelopthediseaseduringfollow‐up
Numberofpersonsdiseasefreeatthestart
Rate:Numberofpersonswhodevelopthediseaseduringfollow‐up
Averagepopulationduringthestudyperiod
ProofofCausalityKockspostulates
Consistency
StrengthandDoseResponse
Specificity
Temporality
Biologicalplausibility
Reversibility
ClassicPopulationStudies
InfectiousDiseaseSirJohnSnow LondonCholeraEpidemic1948
ChronicDiseaseDollandHill SmokingandLungCancer1947
ThomasDawberFraminghamHeartStudies1948
NormativeDataHealthExaminationSurvey 1959
NationalHealthandNutritionalExaminationSurveys 1971
SmokingandLungCancer
DollandHill2
• SurveyofMedicalRegister(59,6000)inOct1951• Simple,short,Questionary• Smokingstatus:Current/Ex/Non‐smokersNumbersmoked• Responserate70%
• Outcomemeasure• RegisterofDeaths
• Results• DeathrateofheavysmokerswasX20thatofnon‐smokers• Increasingmortalitywithincreasingsmokingrates• Effectacrossallagegroups
DollandHillBMJ:19561071‐81
FraminghamStudies
• Framingham–towninMassachusetts
• Studybeganin1948–prospective/cohortstudy
• Enrolled5209participantswhohadnotyetdevelopedsymptomsofcardiovasculardisease
• Agegroup30–62years
• Physicalandlifestylefollow‐upevery2years
OtherFraminghamCohorts
OffspringCohort 1971
OmniCohort(506) 1994
ThirdGeneration 2002
NewOffspring/SpouseCohort 2003
SecondGenerationOmni 2003
RiskFactorsforCardiovascularDisease
IncreaseriskCigarettesmoking 1960Cholesterol,bloodpressure,andECGabnormalities 1961Obesity 1967Menopause 1976Menhavehigherriskthanwomen 1999HighNormalBloodpressure 2001
ReduceRiskPhysicalActivity 1967
HighBloodpressureincreasesriskofStroke 1970
Lessonsfromrecentepidemiologystudies
Helicobacterpyloricausespepticulcerdisease
Helicobacterpyloricausesgastriccancer
Newdata?
or
Didwereinventthewheel?
PepticUlcerDiseaseinthe1950s
Incidence‐2.3per100employees
10thmostcommoncauseofdeath
10%ofhospitaladmissions
SpiralOrganismsintheStomach
BarryMarshall
TheLancetJune4th1983Page1273‐5
Describedfirstcultureofgastricspiralorganisms
SpeculatedonassociationwithgastritisandPUD
RobinWarren
TheLancetJune4th1983Page1273
“theextraordinaryfeaturesofthesebacteriaisthattheyarealmostunknowntoclinicians”
Unansweredepidemiologicalquestions
1.Atwhatagedochildrenbecomeinfected?
2.WillchildrenbecomereinfectedwithH.pylorifollowingeradicationtreatment?
Reinfection
AgeGroup n Patientyearsoffollow‐up
Hpylori+ H.Pylori‐ Reinfectionrate/100PersonyearsUnder5years 6 6.75 4 2 59.2
Over5years 46 97.1 2 44 2.0
Total 52 103.8 6 46 4.8
Rowland et al Gastroenterology 1999
Conclusion
H.Pylorireinfectionoccursrarelyinolderchildren
Poorsocioeconomicconditionsnotariskfactorforreinfection
Havinginfectedparentsorsiblingsisnotariskfactorforreinfection
Youngeragemaybeariskfactorforreinfection
IncidenceofH.pyloriinfection
Requirements– Prospectivestudy
– Cohortofyoungnon‐infectedchildrenatriskofinfectionrequired
– Reasonablelengthoffollow‐up
– Lowsocio‐economicstatus
Enrolled 327 Families
Meanageatbaseline 33.25MonthsSD7.24
Range 23–48months
Female 45%
Age‐SpecificIncidenceofH.pylori
Rowland et al Gastroenterology 2006
MultivariateAnalysis
Factor UnivariateOddsRatio
95%CI MultivariateOddsRatio
95%CI
InfectedMother 5.4 2.4‐11.8 7.2 1.9‐26.3
InfectedSibling 7.3 3.5‐15.2 4.9 2.1‐11.5
>2bottles/day 1.89 0.96‐3.7 5.0 1.1‐21.8
Alwayssleepwithmother
1.89 0.96‐4.6 1.0 0.4‐2.5
Income<£8320/y 1.3‐4.8 1.3 0.6‐2.6
Rowland et al Gastroenterology 2006
HistoricalPerspectiveWheredidHelicobactercomefrom?
Spiralorganismsreportedongastricmucosafor>100yrs
AnimalsBizzozero 1893ArchfMikrBakt
Salomon 1896 CentralblfBakt
HumansKrienitz 1906 DtschmedWochenschrLuger 1917 WeinklinWochnschr
BacteriaandUlcerDiseaseStreptococcuswasaputativeorganism
NotculturedFailedtoinduceulcersinanimalmodels
Rosenow 1913JAMASaunders 1930ArchIntMedCeller 1916MedRecord
SpirochetesDoegens1939ArchPathFreedberg 1940AmJDigDis
1950s
Thetheoryofacidwasborn
Thetheoryofstressandurbanization
AND
TheoccasionaltheoryofinfectionwasunderminedFailuretofindspirochetesin1000biopsies
PalmerGastroenterology1954
Ureainthestomach
LuckandSethBiochemJ1924;18:1227‐31
Roleofgastricurease
FitzgeraldO,MurphyP.Nature;1948162:896
Urease
Antibiotictreatmentdecreasedammoniaandincreasedgastricacidity
LieberandLefevreJClinInvest1959;38:1271‐7
Gastricureaseactivityinmammalsisofbacterialorigin
DelluvaetalBiochemBiophysActa1968;151
SusserandSteinTheLancetSaturday20January1963
Yearofbirth
Cohorteffectandduodenalulcerdisease
100
DeathRatepe
rmillionliving
The1970s
Adventofendoscopyandelectronmicroscopy
Gramnegativespiralbacteriaongastricmucosaofallpatientswithgastritis
Steer1975JClinPath
Cultured“pseudomonasaeruginosa”SteerandColinJones1975
Gut
EndoscopyandelectronmicroscopystudyFung1979AmJGastroenterol
Question
WhydidBarryMarshallcultureH.pyloriandRobinSteerandothersfail?
TheResearchProcess
Researchisagig‐sawandeachpieceofinformationcontributestothepicture
Wemustacquaintourselveswithwhatisknownaboutourparticularareaofinterestinother
disciplines.
Wemustaskwhyandnotfollowblindly.