POLYPHARMACY AND THE RISK OF DRUG-DRUG INTERACTIONS AMONG DANISH ELDERLY - A PRESCRIPTION DATABASE STUDY

Objective: To analyze the use of all subsidized prescription drugs wit h special attention to the elderly (greater than or equal to 70 years of age), including their use of drug combination generally accepted as carrying a risk of severe interactions. Design: Descriptive prevalenc e study. Setting: Odense Pharmacoepidemiological Database. Denmark. Th e fourth quarter of 1994. Subjects: All inhabitants in the county of F unen, Denmark. Main outcome measures: Prevalence of drug use for perso ns <70 and greater than or equal to 70 years of age including number o f drugs used and of drug combinations. Occurrence of 35 drug combinati ons generally accepted as carrying a risk of severe interactions. Resu lts: Among persons less than 70 years, 67.9% used none, 16.5% used one drug and 15.6% used tao or more prescription drugs. The corresponding prevalences for the elderly a ere 35.7%, 15.9% and 48.4%. The 26,337 elderly patients with at least two drugs used 21,293 different combina tions. Of the elderly patients who had purchased greater than or equal to two drugs, 4.4% had combinations of drugs carrying a risk of sever e interactions. Conclusions: Most elderly use drugs and usually severa l drugs concomitantly. The elderly form a heterogeneous group of drug users. Drug combinations carrying a risk of severe interactions are re latively frequent.