Inappropriate drug use in the elderly: a nationwide register-based study.

BACKGROUND: Potentially inappropriate drug use (IDU) is an important and preventable safety concern in the care of elderly patients and has been associated with adverse drug reactions, hospitalization, and mortality.

OBJECTIVE: To estimate the prevalence of potentially IDU among the elderly in Sweden and investigate whether age, sex, and number of dispensed drugs are associated with IDU.

METHODS: We analyzed data on age, sex, and dispensed drugs for people aged 75 years and older who were listed in the Swedish Prescribed Drug Register from October-December 2005 (N = 732,228). The main outcome measures of IDU were prescription of anticholinergics, prescription of long-acting benzodiazepines, concurrent use of 3 or more psychotropic drugs, and an indication of potentially serious drug-drug interactions.

RESULTS: Prevalence for IDU was 17%; for anticholinergic drugs 6%, long-acting benzodiazepines 5%, 3 or more psychotropic drugs 5%, and potentially serious drug-drug interactions 4%. After adjustment for age and sex, number of dispensed drugs was strongly associated with all 4 measures of IDU. After adjustment for sex and number of dispensed drugs, increasing age was moderately associated with a higher probability of IDU, long-acting benzodiazepines, and 3 or more psychotropic drugs, After adjustment for age and number of dispensed drugs, women had a slightly increased probability of IDU, anticholinergic drugs, long-acting benzodiazepines, and 3 or more psychotropic drugs.

CONCLUSIONS: IDU was fairly common among the elderly in Sweden in 2005 and was strongly connected to the number of dispensed drugs they were taking. Older age and female sex were related to inappropriate use of psychotropic drugs, whereas the opposite relationship prevailed for potentially serious drug-drug interactions. Future research is needed to determine whether IDU will become more common due to increasing use of drugs among elderly persons. The challenge is to balance the problems related to IDU without denying older people potentially valuable drug therapy.