[Big differences in the frequency of polypharmacy between physicians].

Polypharmacy, the simultaneous use of multiple drugs, is associated with adverse drug reactions, medication errors, and increased risk of hospitalisation. When the number of drugs is five or more (major polypharmacy), a significant risk may be present. We analysed the prevalence of major polypharmacy among listed patients, and identified possible predictors of major polypharmacy related to the practice. Prescription data were retrieved from the Odense Pharmaco-epidemiological Database and the age and sex standardised prevalence rate of major polypharmacy was calculated for each practice (n = 173). Possible predictors of major polypharmacy related to the GPs were analysed by backward stepwise linear multiple regression. A six-fold variation between practices in the prevalence of major polypharmacy was found, i.e. from 16 to 96 per 1000 listed patients (median: 42). Predictors related to the practice structure, workload, clinical work profile, and prescribing profile could explain 56% of the variation.