Trends in polypharmacy and potential drug-drug interactions across educational groups in elderly patients in Sweden for the period 1992 – 2002

Abstract

This study investigates the changes in drug use, polypharmacy and potential drug-drug interactions (DDIs) between educational groups of Swedish elderly over a 10-year period from 1992 - 2002. We used data from SWEOLD I (n = 512) from 1992 and SWEOLD II from 2002 (n = 561), which are nationally representative surveys of the elderly population in Sweden aged 77 years and older. Both community-based and institutionalized persons were included. Information on drug use was based on personal interviews and all drugs used in the two weeks prior to the studies were recorded. The three outcomes under study were drug use, polypharmacy (concurrent use of five or more drugs), and potential DDIs. In the SWEOLD data from 1992 - 2002, the mean number of drugs used per person increased from 2.5 - 4.4. Overall, 81% of the study participants were drug users in 1992 as compared to 88% in 2002. The prevalence of polypharmacy increased 3-fold (from 18% in 1992 to 42% in 2002) after controlling for age and gender. In both SWEOLD surveys, the less educated reported polypharmacy more often (19% in 1992 and 46% in 2002) than the higher educated (12% in 1992 and 36% in 2002). Potential DDIs also increased, both among the less educated (14% in 1992 to 26% in 2002) and the higher educated (18% in 1992 to 24% in 2002). The most pronounced changes in the consumption of specific drug groups were observed in antithrombotic agents, beta-blocking agents, ACE inhibitors, and vitamin B12 and folic acid. In general, the use of most therapeutic classes increased more among the well educated compared to less educated men between 1992 and 2002, whereas the opposite relationship prevailed among women. This study indicates that the use of drugs, polypharmacy and potential DDIs have increased during 1992 to 2002 among the elderly. These changes were most prominent among the less educated women. Polypharmacy and potential DDIs represent potential health hazards for the elderly. Therefore, the trends of increasing polypharmacy and drug-drug interactions deserve attention and the mechanisms behind should be investigated further.