Polypharmacy Among the Elderly in a List-Patient System

BACKGROUND Polypharmacy, i.e. the simultaneous use of multiple drugs, is known to be associated with compliance errors and adverse drug reactions. Norway has a list-patient system in general practice, formalizing the relationship between the patient and his/her regular general practitioner (GP). One important aim with a list-patient system is to secure medical quality in primary care by giving the GP the responsibility for coordinating the medical treatment. OBJECTIVE To examine the regular GP's role in polypharmacy to the home-dwelling elderly in Norway and to determine by how much multiple prescribers increase the risk of polypharmacy. METHODS This was a population registry study based on data on all prescription drugs dispensed at pharmacies to patients 70 years and older from the Norwegian Prescription Database, merged with data on GPs and GPs' patient lists from the Regular General Practitioner Database. The dataset included 624,308 patients and 4520 GPs in the period from 2004 to 2007. Outcome measures were: number of drug-substances prescribed and dispensed per patient by the regular GP, other GPs, non-GP specialists and hospital doctors; polypharmacy, defined as five or more prescribed and dispensed substances in the same quarter; excessive polypharmacy, defined as ten or more prescribed and dispensed substances in the same quarter. RESULTS Polypharmacy is high and increasing despite the list-patient system. GPs prescribe all the substances that cause polypharmacy in 64 % of the incidents, but the patients' risk of polypharmacy increases substantially with number of prescribers, odds ratio 2.32 (95 % CI 2.31-2.33). CONCLUSION GPs have a major role in the high and increasing polypharmacy among the elderly in Norway. Any intervention intending to improve the situation must necessarily include the GPs.