Table Of Content

EvaluationofDrug UseReview Demonstration AbtAssociatesInc. Projects 55WheelerStreet ContractNo.: Cambridge,Massachusetts 02138-1168 500-93-0002 617492-7100telephone 617492-5219facsimile FinalReport HampdenSquare,Suite500 4800MontgomeryLane October28, 1998 Bethesda,Maryland 20814-5341 Submittedto: 301913-0500telephone JayP.Bae,PhD 301652-3618facsimile ProjectOfficer HealthCareFinancingAdministrauo OfficeofResearchandDemonstratu C-3-16-26CentralBuilding 640NorthLaSalleStreet 7500SecurityBoulevard Suite400 Baltimore,MD21244-1850 Chicago,Illinois 60610-378i Submittedby: 312867-4000telephone AbtAssociatesInc. 312867-4200facsimile C55amWbhreiedlgeer,SMtrAeet02138 Table ofContents 1.0 Background 1-1 1.1 TheMedicaidDURDemonstrations 1-2 ProjectC.A.R.E 1-2 IowaOPDURDemonstrationProject 1-3 1.2 ApproachtotheExternalEvaluation 1-3 1.2.1 ComponentsoftheEvaluation 1-4 1.2.2 EvaluationChallenges 1-5 1.2.3 TheCoreModel 1-6 1.3 DURandMedicaidDrugPolicy:TrendsSinceOBRA1990 1-7 1.3.1 MedicaidManagedCarePenetrationintheFourStates 1-7 1.3.2 MedicaidRegulationofPrescriptionDrugs 1-11 1.4 ImprovingPrescribing 1-11 1.4.1 Introduction 1-17 1.4.2 TheRoleofEducationalInterventions 1-17 1.4.3 IndividualEducationalInterventions 1-18 1.4.4 GroupEducationalInterventions 1-19 1.4.5 FeedbackonPrescribingPractices 1-20 1.4.6 ClinicalPharmacistSystems 1-22 1.4.7 TheRoleofIncentives 1-22 1.4.8 TheRoleofRegulatoryandAdministrativeRestrictions 1-23 1.4.9 Conclusions 1-24 2.0 EvaluationResearchTools 2-1 2.1 ThePSUScreener 2-1 2.1.1 HistoryofthePennStateScreener 2-1 2.1.2 ThePSUScreener:AnOverview 2-2 2.1.3 StudyObjectiveServedbythePSUScreener 2-3 2.1.4 UpdatingandImplementingtheUM/PCPSCriteria 2-3 2.1.5 PortingandVerificationofPSUScreener 2-5 2.1.6 ScreenDefinitions 2-5 2.2 TheDUROutcomesDatabase 2-12 2.2.1 DevelopmentofTheDUROutcomesBibliographicDatabase 2-12 2.2.2 SelectionofCandidateClinicalOutcomes 2-14 3.0 DrugUseandPrescribingProblemsinFourStateMedicaidPrograms 3-1 3.1 Background 3-1 3.2 Methods 3-2 3.3 DrugUsebyTherapeuticClass 3-4 AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport i TableofContents(continued) 3.4 DURScreenFailureResults 3-5 3.4.1 DURCriteriaAssociatedwithConsistentlyLowFailureRates 3-5 3.4.2 DURCriteriaAssociatedwithConsistentlyHighFailureRates 3-6 3.4.3 ComparativeFindingsbyDrugClass 3-9 3.4.4 SummaryMeasuresofDURFailureRates 3-16 3.5 SummaryandConclusions 3-18 4.0 PayingforPharmacists'CognitiveServices:TheProjectC.A.R.E.Demonstration 4-1 4.1 Background 4"1 4.2 PharmacistsandPrescribes:AttitudesTowardDURandtheDemonstration 4-3 4.2.1 Background 4-3 4.2.2 OBRA1990Requirements 4-3 4.2.3 AttitudesTowardCognitiveServices 4-4 4.2.4 PaymentforProvisionofCognitiveServices 4-5 4.2.5 ThePharmacist-PrescriberRelationship 4-6 4.2.6 PharmacistAttitudesTowardWork 4-7 4.2.7 RecommendationsforImprovedPrescribing 4-7 4.2.8 Conclusion 4"7 4.3 ProjectC.A.R.E.:Implementation 4'8 4.3.1 Recruitment,OrientationandTraining 4-8 4.3.2 SamplingandEnrollmentofPharmaciesandCohortMaintenance 4-8 4.3.3 ImplementingtheCSPaymentIntervention 4-10 4.3.4 RefinementsandModificationstotheCSPaymentIntervention 4-10 4.3.5 Organization,StaffingandDataManagement 4-12 4.3.6 OrganizationalandStaffingIssues: ProblemsandSolutions 4-12 4.3.7 DataBaseDesignandImplementation:ProblemsandSolutions 4-12 4.3.8 DataFlows 4"13 4.3.9 ProgramEvaluation 4-14 4.3.10 Conclusion 4"14 4.4 FindingsontheImpactoftheCognitiveServicesDemonstrationonDownstream UtilizationandCosts 4-16 4.4.1 Background 4"16 4.4.2 DataandMethods 4"17 4.4.3 Findings 4"25 4.4.4 Discussion 4"28 4.5 EffectsofProjectC.A.R.E.onPrescriptionUseandCosts 4-30 4.5.1 DataandStudyPopulation 4"30 4.5.2 Methods 4'31 4.5.3 Findings 4'31 4.5.4 Discussion •••• 4~34 AbiAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport ii TableofContents(continued) 4.6 EffectsoftheCognit—iveServicesDemonstrationonScreenFailures 4-35 4.7 OutcomesAnalyses MethodsandData 4-48 4.8 TheImpactofProjectC.A.R.E.onGastrointestinalEvents 4-53 4.9 TheImpactoftheCognitiveServicesDemonstrationonAdverseClinical OutcomesRelatedtotheUseofAntidepressants 4-66 4.10 TheImpactoftheCognitiveServicesDemonstrationonAdverseClinical OutcomesRelatedtotheUseofBenzodiazepines 4-84 4.11 TheImpactofProjectC.A.R.E.onAdverseOutcomesRelatedto InappropriatePrescribingofCardiovascularDrugs 4-101 4.12 CostsandCost-EffectivenessofProjectC.A.R.E 4-121 5.0 On-LineProspectiveDrugUseReview: TheOPDURDemonstration 5-1 5.1 Background 5-1 5.2 IowaandMarylandPharmacistsPrescribers:AttitudesTowardDURandthe Demonstration 5-2 5.3 TheIowaOPDURDemonstration: Implementation 5-9 5.4 FindingsontheImpactoftheOPDURDemonstrationonDownstream UtilizationandCosts 5-12 5.4.1 Background 5-12 5.4.2 DataandMethods 5-12 5.4.3 Findings 5-21 5.4.4 Discussion 5-28 5.5 EffectsoftheOPDURDemonstrationonPrescriptionDrugUseandCosts 5-30 5.5.1 DataandStudyPopulation 5-30 5.5.2 Methods 5-31 5.5.3 Findings 5-31 5.5.4 Discussion 5-34 5.6 EffectsoftheOPDU—RDemonstrationProjectonScreenFailures 5-35 5.7 OutcomesAnalyses MethodsandData 5-49 5.8 TheImpactofOPDURonGastrointestinalEvents 5-54 5.9 TheImpactoftheOPDURDemonstrationProjectonAdverseClinical OutcomesRelatedtotheUseofAntidepressants 5-67 5.10 TheImpactoftheOPDURDemonstrationProjectonAdverseOutcomes RelatedtotheUseofBenzodiazepines 5-87 5.11 TheImpactoftheIowaOPDURDemonstrationProjectonAdverseOutcomes RelatedtoInappropriatePrescribingofCardiovascularDrugs 5-105 5.12 TheImpactoftheMarylandProDURInterventionfor0-AgonistInhaler UseonElderlyDual-EligibleMedicaidRecipients 5-126 5.13 CostsandCost-EffectivenessoftheOPDURDemonstration 5-145 AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport iii TableofContents(continued) 6.0 RetrospectiveDrugUseReview 6-1 6666....1324 ITTTnhhhteeeroIIIdmmmupppcaaatciccotttnooofffRRRDDDUUURRR———IIMooawwryaalMMaeendddiiccRaaDiiddURDDUULeRRttBBeoorsaarroddnLLZeeattnttteearrsscooUnnseMSialsmoeptreorsotlol 66--66-13-1630 7.0 Conclusions 7.1 SummaryofFindings 7-1 7.2 Discussion 7-1 AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport iv Evaluation of Drug Use Review Demonstration Projects Final Report 1.0 Background TheOmnibusBudgetReconciliationActof1990(OBRA1990)requiredthatallstateMedicaid programsimplementdrugusereview(DUR). Thislegislationalsomandateddemonstrationsof innovativemodelsofDUR,andin1992,theHealthCareFinancingAdministration(HCFA)funded twoexperimentsmanagedbystateMedicaidagencies. InProjectC.A.R.E., Washington's DepartmentofSocialandHumanServicescollaboratedwiththeUniversityofWashingtonSchoolof Pharmacytotesttheeffectsofpayingpharmaciststoprovidecognitiveservices(CS). TheIowa MedicaidOPDURDemonstrationProject,involvingIowa'sDepartmentofHumanResources, togetherwithresearchersfromtheUniversityofIowa,DrakeUniversityandtheIowaPharmacists Association,testedon-lineprospectivedrugusereview(OPDUR). In1993,HCFAchoseateamledbyAbtAssociatesInc.toconductanexternalevaluationofboth demonstrations,aswellastargetedstudiesoftheeffectivenessofretrospectivedrugusereview (RDUR).1 InordertoincreaseprecisioninquantitativeanalysesoftheeffectsofOPDUR,the evaluationteamrecruitedtwoadditionalstatesfortheexternalevaluation:Maryland(designateda"co- experimental"statewithanOPDURsystemsimilarinstructuretoIowa's),andGeorgia(designateda "comparison"statewithnoOPDURsysteminplace). Becausenootherstatewaspayingpharmacists forCSatthetimetheevaluationdesignwasfinalized,itprovedtobeimpossibletofindadditional statestoaugmenttheevaluationofWashington'sdemonstration. Therefore,theexternalevaluationof CSpaymenteffectsreliesonlyonWashingtondata. Thisisthefinalreportoftheexternalevaluation.2 Thefollowingsectionsofthischapterintroducethe demonstrationsandtheevaluationdesign,reviewtheMedicaidpolicycontextwithinwhichthe evaluationstatesoperated,andreviewresearchevidenceonprogramsdesignedtoimproveprescribing. ChapterTwodescribestwokeyresearchtoolsusedintheevaluation:the"PSUscreener"andadata basethatrelates prescribingproblemscodifiedinPSUscreeningcriteriatoadverseclinicaloutcomes, definedbyICD-9diagnosiscodes. ChapterThreepresentsbaselinedescriptivestatisticsondrug prescribingandprescribingproblemsinthefourevaluationstates. ChapterFourevaluatesProject C.A.R.E.throughaseriesofstudiesfocusedonCSpaymenteffectsintheWashingtondemonstration, includinganalysesofphysicians'andpharmacists'attitudesandperceptionstowardDUR,problems encounteredinimplementingthedemonstration,andestimatedeffectsofCSpaymentonprescription 1 InadditiontoAbtAssociates,theteamincludedinvestigatorsfromPennsylvaniaStateUniversity,JENAssociates,Inc. andCasalsandAssociates. 2 BoththeWashingtonandIowademonstrationscompletedtheirownevaluations.SeeChristensen,D.B.etal.. PPHraCoyjFmeceAtn.CtoAonnftnruPahacaltrmRNaeocp.iosr1ttls.-CfHo-rC90CF2oA2g9n.CiotNoiopveevreSametrbivevierceAs1.g9r9R6ee,esmuaeltnnsdtoCNfhort.ihsec1hWli-alCsl-eh9si,0n2Eg3.t2Ao/.n7,.STtShaeetpetICeo.mwAba.eRMr.eEd1.9i9cD7ae.imdonOsPtDraUtiRonDePmroojnescttr.ation — AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects FinalReport 1-1 drugutilization,screenfailures,"downstream"MedicareandMedicaid-reimbursedutilization,and clinicaloutcomes. Infourseparateoutcomesanalyses,theevaluationusedepidemiologicalmethodsto study theeffectsofDURon:1)gastrointestinalbleedingassociatedwiththemisuseofNSAIDS,2)a varietyofoutcomesassociatedwith antidepressantprescribingproblems(e.g.conductiondisorders, falls),3)hipfracturesandotheroutcomesassociatedwithbenzodiazepineprescribingproblems,4) adverseoutcomesassociatedwithACEinhibitor,calciumchannelblockeranddigoxinprescribing problems. Thischapterconcludeswithadiscussionofthecostsandcost-effectivenessofcognitive servicespayment. ChapterFiverepeatstheseanalysesforanevaluationofOPDUR.Thischapteralso includesafifthepidemiologicalstudyoftheeffectsofMaryland'sOPDURprogramonoutcomes associatedwithbeta-agonistinhalerprescribingproblems. ChapterSixreportsonthreestudiesofthe effectsofRDURonprescriptiondrugutilization. TwostudiesfocusonIowainterventionsinvolving thedrugsMisoprostolandSalmeterol,whileonereportsresultsfromanH2blocker(Zantac) interventioninMaryland. ChapterSevenconcludesthereportwithadiscussionofimplicationsfor Medicaidprescriptiondrugpolicy. 1.1 TheMedicaidDURDemonstrations WashingtonandIowadesignedtheDURdemonstrationstoimprovedrugprescribingbyinfluencing pharmacists'behavior. Howevereachdemonstrationtestedadifferentassumptionaboutwhat incentivesaremosteffectiveinachievingthedesiredresults. ProjectC.A.R.E. ProjectC.A.R.E.paidpharmacistsinatreatmentgroupforprovidingcognitiveservices,definedas professionalactivitiesotherthandispensingdrugsthatarerelatedtodispensingandthatarenot routine,hypothesizingthatpaymentwouldencouragemoreandmoreeffectiveCS.Totesttheeffects ofpayingforCS,ProjectC.A.R.E.recruited200pharmaciesandrandomlyassignedgeographic clustersofpharmaciestotwogroups:110pharmaciesingroupAclusters receivedpaymentforCS servicesanddocumentation,and90pharmaciesingroupBclustersreceivedpaymentonlyfor documentingCSprovision. Clusterswerecreatedtocapturepatternsofprescriberuseofpharmacies, minimizing"cross-over"ofprescribersfromonepharmacytypetoanother. Investigatorsalsoselected GroupC,a"silentcontrol"sampleofpharmaciesthatreceivednoCS-relatedpaymentsandnonotice thattheyhadbeenselected.ProjectC.A.R.E.operatedfromFebruary1994throughSeptember1995, sixmonthslongerthanoriginallyplanned. Tobeeligibleforpaymentunderthedemonstration,CShadtoberelatedtodispensingaprescription drugtoaMedicaidbeneficiary, butnota"requisitepartofdispensing"(i.e.,accepting,interpreting, andclarifyingaprescriptionorder,preparingaprescription,deliveringittoapatient),andhadto conformtocertainaprioriassumptionsaboutplausibility.3 ForeachCSevent,ProjectC.A.R.E. askedpharmaciststodocumenttheproblem,theintervention,andtheresult.Investigatorsthen determinedwhatcombinationsofthesethreecomponents"madesense."Experiencegainedduringthe demonstrationexpandedthesetofcodesdeterminedtobereasonable. Finally,thedemonstration 3 Christensen,D.B.,op.cit.,page17 AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport 1-2 limitedpaymenttotwoCSperpatientperday.UnlikeIowaOPDUR,ProjectC.A.R.E.didnotfocus pharmacists'attentiononaspecificlistofdrugs. Foreligiblecognitiveservices,GroupApharmaciesreceivedperservicepaymentsof$4.00fora "briefencounter"(sixminutesorless)or$6.00foran"extendedencounter"(oversixminutes). Both AandBpharmaciesreceived$40permonthforsubmittingCSdocumentationtotheUniversityof Washington.GroupCpharmaciesreceivednopaymentsunderthedemonstration. IowaOPDURDemonstrationProject IowalinkedallpharmaciesparticipatingintheOPDURdemonstrationtoanon-lineDURscreenerthat reviewedeachMedicaidprescriptiondrugclaimasitwassubmittedelectronicallyforpayment. Pharmaciesinthetreatmentgroupreceivedmessagesthatidentifiedpotentialprescriptionproblems. Controlgrouppharmaciesreceivednomessages. Bothtreatmentandcontrolgrouppharmacieswere askedtodocumentallcognitiveservicesprovided,inordertodescribedemonstrationeffectson pharmacistsbehavior. Iowadidnotpaypharmacistsforprovidingordocumentingcognitiveservices. UnlikeWashington,Iowadefinedspecificproblemsanddrugsasthefocusofitsintervention. Iowa investigatorsworkedwithUnisys,Iowa'sMedicaidfiscalagent,tocustomizeProDUR(TM),a softwareproductofNationalDataCorporation. Operationally,theIowaOPDURscreensweredefined bycriteriadevelopedbytheUniversityofMarylandandthePhiladelphiaCollegeofPharmacyand Science.Criteriaincludeddrug-druginteractions,therapeuticduplications,andhighdailydosefor eightclassesofdrugs:angiotensinconvertingenzyme(ACE)inhibitors,calciumchannelblockers, cardiacglycosides,benzodiazepines,antidepressants,antipsychotics,histamineH2receptor antagonists,andnonsteroidalantiinflammatoryagents(NSAIDS). Iowaalsoscreenedearlyrefillsfor alldrugs. Iowarandomizedpharmacyclusterstotreatmentandcontrolgroups. Of223pharmaciesrecruitedfor thedemonstration,110weretreatmentand113control. ThedemonstrationoperatedfromJune1994 throughJune1997. 1.2 ApproachtotheExternalEvaluation HCFAaskedtheexternalevaluatortodeterminewhetherornotthedemonstrationswereeffective1)in improvingdruguseand2)inreducingthenegativeconsequencesofdrugmisuse,measuredinterms ofadverseclinicaleventsandhealthservicesutilization.Shouldoneorbothofthedemonstrations showeffectiveness,theevaluatorwasalsoexpectedtodeterminethecostsofachievingthese improvements,forcomparisonwithotherpoliciesandprogramsdesignedtoachievetheseends. This sectiondescribesthecomponentsoftheevaluation,howtheevaluatoraddressedmethodological challenges,andtheunderlyingmodelusedtoestimateeffects. 1.2.1 ComponentsoftheEvaluation Therearethreemajorcomponentsoftheexternalevaluation. Thebasicevaluationmethodologywas replicated,separately,forProjectC.A.R.E.andfortheIowaOPDURDemonstrationProject. These componentsinclude: AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport 1-3 1) Descriptivecontextualinformation. Thesesectionsincludedadiscussionofproblems encounteredinimplementingthedemonstrations,basedonreportsfromthe demonstrationsandsitevisitsconductedbystafffromtheAbtAssociatesteam;analyses ofattitudesandperceptionsofpharmacistsandprescriberstowardDURandthe demonstrations,basedonasurveyofpharmacistsconductedinWashingtonin1995and inIowain1996,aswellaspharmacistandprescriberfocusgroups,heldinallfourstates during1995;baselinecomparisonsamongthefourevaluationstatesofMedicaid prescriptiondrugutilizationandproblems. 2) Testsofaggregatedemonstrationeffects. Threestudiesutilizedacommonstatistical modeltotestfordemonstrationeffectson a) thevolumeandcostsofprescriptiondrugutilization-InIowa,whereduplicationand earlyrefillareOPDURexplicitscreens,butunder-prescriptionisnot,onewouldnot expecttofindthedemonstrationassociatedwithincreaseddrugutilization. However, inWashington,pharmacistsarenotguidedinthismannerbyexplicitscreens,andso aggregateeffectsondrugutilizationmaybepositiveornegative. b) thefrequencyofdrugproblems,measuredasfailuresofPSUscreenercriteria-The externalevaluatorusedthePSUscreenertomeasureeffectsondrugproblemsbecause itistheonlyreliabletoolavailableforthispurposeacrossalloftheevaluationstates. ScreenfailuresintheeightPSUdrugcategoriesareexpectedtodeclineinIowa, becauseIowascreenedagainstcriteriadefinedforthesedrugs. Failuresmayhave declinedforthesedrugsinWashington,butthereisnoreasontobelievethateffects wouldbeconcentratedinthem. c) thevolumeandcostsof"downstream"MedicareandMedicaidnon-drugutilization -Bothinterventionswereexpectedtobeeffectiveinreducingthecostsof downstreamutilization,inparticular,utilizationassociatedwithdiagnosesidentified withless-than-optimalprescribing(madeoperationalbythePSUscreen failure/outcomedatabase),emergencyroomvisits,andphysicianofficevisits. However,theremaybeunintendedeffectsonthevolumeof"optimal"prescribing,so thatdecreasesinutilizationofcertaindrugsresultinincreaseddownstreamutilization inat-riskpopulations. 3) Focusedtestsofdemonstrationeffects.Theevaluationconductedfiveepidemiological analysesoftheeffectsofthedemonstrationsonadverseclinicaloutcomes,inthecontext ofspecificprescribingproblems. Forexample,byreducingthefrequencyofover- utilizationofbenzodiazepines,thedemonstrationmayhaveeffectedadecreaseinfalls,an associatedoutcome. Becausethesestudiesfocusedononeclinicalproblem,modelingand choiceofcovariateswas,tosomeextent,tailoredtoeachproblem. Thestudysubjects were:NSAIDS/GIbleeding;benzodiazepinesandfalls;cardiacdrugsandoutcomes,beta- agonistinhalersandoutcomes;andantidepressantsandoutcomes. AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects—FinalReport 1-4 1.2.2 EvaluationChallenges Ineverydemonstration,challengesemergewhenthedemonstrationdesignmeetstherealitiesof limitedresources,institutionalrigiditiesandrandomunforeseenevents. Thesearediscussedlater,in ChaptersFour(ProjectC.A.R.E.)andChapterFive(IowaOPDURDemonstrationProject). These demonstrationsposedconceptualchallengesaswell. Definingsubjects. BothWashingtonandIowarandomlyassignedpharmacyclusterstotreatmentand controlgroups,becausetheinterventionsweredesignedtoaffectpharmacists'behavior. Theobjectof thedemonstration,however,wastoimproveprescribingandreducethefrequencyofpreventable adverseoutcomesforMedicaidbeneficiaries. Therefore,theevaluatorschosetoanalyzeeffectson beneficiariesratherthanpharmaciesorpharmacists. Thismighthaveposedaproblemforthedesign, ifbeneficiariesfilledprescriptionsatbothtreatmentandcontrolpharmacies-samplinginboth demonstrationswasstructuredtominimizecrossoverofphysicians,withtheexpectationthat beneficiarycrossoverwouldbeminimizedaswell. Thisstrategywaslargelysuccessful. In Washington,fewerthanfivepercentofsubjectsusedbothGroupAandBpharmaciesduringthestudy period;inIowa,aboutsevenpercentofsubjectsusedbothGroupAandBpharmaciesduringthestudy period. Becausetheproportionofcrossoverswassmallinbothdemonstrations,theseindividualswere droppedfromallanalysesofdemonstrationeffects. Clustersamplingalsointroducedapotentialsourceofvariationthathadtobecontrolledinthe analysesinordertobesurethatestimatesofthedemonstrationeffectswereunbiased. Inpart,because thedemonstrationssampledafairlysmallnumberofclusters(37inWashingtonand151inIowa),the investigatorswereconcernedthatsomecluster-leveldemographicorotherfactorsmightbecorrelated withtreatmentstatus,potentiallyproducingestimatesofdemonstrationeffectswithinaccuratestandard errors. Measurablefactorswerecontrolleddirectly,throughcluster-levelaveragesthatwereincluded asregressorsinmultivariatemodels. Inaddition,investigatorsestimatedthemodelsusingaversionof theWhite/Hubervarianceestimationmethodthatadjustsforcorrelationwithinclusters. Definingexposure. Itisstandardpracticeinevaluatingsocialexperimentstoapplyan"intenttotreat" standardfordefiningexposure. Thatis,allmembersofthetreatmentgroupareexposedtothe demonstrationinterventionassoonastheinterventionisavailable,regardlessofwhetherornot subjectsactivelyparticipateinthedemonstration. Inthecontextofthesedemonstrations,onecan definepharmaciesasexposedbythedateonwhichtheywereeligibleforCSpayment(Project C.A.R.E.)orreadytoreceiveOPDURmessages(Iowa).DefiningexposureforindividualMedicaid recipientsislessstraightforward. Knowledgeablerecipientscouldbeawareofthetimingandpurpose ofthedemonstrations,withouthavinganydirectcontactwithademonstrationpharmacy, andthis knowledgecouldaffecttheirbehavior. Thisconjectureseemsimplausible. Morelikely,recipientsare exposedwhenfirstfillingaprescriptionafterthedemonstrationshavebegun.Thisdefinitionwas adoptedfortheevaluation. Sincepharmaciesinbothstatesenteredthedemonstrationsinwaves, recipientexposurereflectstheserecruitmentpatterns. Precision. Twofactorssuggestthatdemonstrationeffects,iftheyexist,willbesmallanddifficultto find. First,theresearchliteratureimpliesthatthefrequencyofprescribingerrorswithpotentially harmfulandcostlyconsequencesisconsiderablylessthanonepercent[(Ruppetal.(1988,1992)]. If, forexample,thedemonstrationreducedprescribingerrorby25percent,fromafrequencyof0.8 percent,theevaluatorwouldbesearchingforanabsoluteeffectof0.2percentagepoints. Second,the — AbtAssociatesInc. HCFAEvaluationofDrugReviewProjects FinalReport 1-5