title: Correspondence between general practitioner-reported medication use and timing of prescription dispensation.
abstract: Epidemiologic studies often rely on drug dispensation records to measure medication intake. We aimed to estimate correspondence between general practitioner (GP)-reported treatment and timing of prescription dispensation. From seven GPs in northern Denmark, we obtained 317 prescription records for 286 patients treated with ten commonly prescribed medication types for chronic diseases. We linked the GP-reported information to the regional prescription database to retrieve patients' prescription records both prospectively and retrospectively in relation to the GP-reported date of treatment (index date, August 20, 2008 for all patients). We computed overall and medication-specific correspondence between GP-reported treatment and the timing of dispensation. We computed correspondence based on both exact medication and therapeutic subgroup agreement. The correspondence for dispensation within ±90 days of GP-reported treatment was 0.81 (95% confidence interval = 0.76-0.85) with variation by medication type, ranging from 0.55 for ACE-inhibitors to 1.00 for oral glucose-lowering agents. The correspondence was greater when analyzed within therapeutic groups than when analyzed for exact medications within these groups.
authors.affiliation: Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Sigrun Alba
authors.initials: SA
authors.lastname: Johannesdottir
authors.forename: Merete Lund
authors.initials: ML
authors.lastname: Mægbæk
authors.forename: Jens Georg
authors.initials: JG
authors.lastname: Hansen
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Lash
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.forename: Vera
authors.initials: V
authors.lastname: Ehrenstein