Institutionalization as a risk factor for inappropriate drug use in the elderly: a Swedish nationwide register-based study.

BACKGROUND: Few studies have investigated institutionalization as a potential risk factor for potentially inappropriate drug use (PIDU). Sweden now has unique possibilities for comparisons of drug use in large populations of institutionalized and home-dwelling elderly through linkage of the Swedish Prescribed Drug Register (SPDR) with the Swedish Social Services Register.

OBJECTIVE: To compare PIDU in institutionalized versus home-dwelling elderly persons in Sweden.

METHODS: We conducted a cross-sectional retrospective study of 1,260,843 home-dwelling and 86,721 institutionalized elderly individuals. We analyzed data on age, sex, and dispensed drugs for individuals aged 65 years or older registered in the SPDR from July to September 2008. Data on type of housing were retrieved from the Social Services Register. The main outcome measures of PIDU were use of anticholinergic drugs, long-acting benzodiazepines, concurrent use of 3 or more psychotropics, and potentially serious drug-drug interactions (DDIs).

RESULTS: Thirty percent of the institutionalized and 12% of the home-dwelling elderly were exposed to PIDU. Living in an institution was strongly associated with overall PIDU (OR 2.36; 95% CI 2.29 to 2.44), use of anticholinergic drugs (OR 2.58; 95% CI 2.48 to 2.68), long-acting benzodiazepines (OR 1.50; 95% CI 1.41 to 1.60), and concurrent use of 3 or more psychotropics (OR 7.26; 95% CI 6.96 to 7.59), after controlling for age, sex, and number of drugs (used as proxy for comorbidity). However, institutionalization was associated with a lower probability of potentially serious DDIs (OR 0.60; 95% CI 0.55 to 0.65).

CONCLUSIONS: Our results indicate that institutionalization is a potential risk factor for PIDU. This implies that more cautious prescribing is warranted in institutions, where the frailest and most vulnerable elderly individuals reside. Research is needed to identify underlying risk factors for PIDU within these settings.