How Chronic Is Polypharmacy in Old Age? A Longitudinal Nationwide Cohort Study

Abstract

Objective: To evaluate the chronicity of polypharmacy among older adults and to identify factors associated with chronic polypharmacy.

Design: Longitudinal cohort study using register data.

Setting: Nationwide, Sweden.

Participants: All 711,432 older adults (aged 65 years and older) living in Sweden with five or more prescription drugs in October 2010 were included and followed up until December 2013. Mean age at baseline was 77 (SD = 7.8) years, 59% were women, and 7% lived in nursing homes.

Measurement: Monthly changes in the exposure to polypharmacy. Data regarding prescription drug use were extracted from the Swedish Prescribed Drugs Register.

Results: Overall, 82% were continuously exposed to polypharmacy for 6 months or longer, and 74% for 12 months or longer. The proportion of individuals who remained exposed until the end of the study was 55%. Among the 21,361 individuals who had not been exposed to polypharmacy during the 6-month period before baseline (ie, with a new episode of polypharmacy), only 30% remained exposed for 6 months or longer. The proportion of older adults who spent at least 80% of their follow-up time with polypharmacy was substantially higher among prevalent polypharmacy users at baseline than among those with a new polypharmacy episode (80% vs 24%; P < .01). Factors associated with chronic polypharmacy included higher age, female sex, living in an institution, chronic multimorbidity, and multidose dispensing.

Conclusion: Polypharmacy is most often chronic, although a substantial share of older adults experience short, recurring episodes of polypharmacy and are thus exposed to its potential harms in a transient rather than persistent manner. J Am Geriatr Soc 67:455-462, 2019.

Keywords: drugs; duration; epidemiology; medication; polypharmacy.