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 (≥65 years) living in Sweden with 5 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 during ≥6 months, and 74% during ≥12 months. 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 (i.e. with a new episode of polypharmacy), only 30% remained exposed for ≥6 months. 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<0.01). Factors associated with chronic polypharmacy included higher age, female gender, living in an institution, chronic multimorbidity, and multi-dose 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.
