BACKGROUND: Potentially inappropriate prescribing (PIP) describes medications where risk generally outweighs benefit for older people. Cross-sectional studies suggest an association between PIP and poorer health outcomes but there is a paucity of prospective cohort studies. This study investigates the longitudinal association of PIP with adverse drug events (ADEs), health related quality of life, and accident & emergency visits.

METHODS: Study design: Two-year (2010-2012) prospective cohort study (n = 904, ≥70 years, community-dwelling) with linked pharmacy dispensing data.

EXPOSURE: Baseline PIP: Screening Tool for Older Persons potentially Inappropriate Prescriptions (STOPP) and Beers 2012 applied 12 months prior.

STUDY OUTCOMES: ADEs (patient interview), health related quality of life (EQ-5D-3L: patient questionnaire), and accident & emergency visits (general practice medical record review).

STATISTICAL ANALYSIS: Descriptive statistics: Poisson (incidence rate ratio [95% confidence interval [CI]], linear regression models [regression coefficient [95% CI]], and logistic [odds ratio [OR] [95% CI]).

RESULTS: Of 791 participants eligible for follow-up, 673 (85%) returned a questionnaire and 605 (77%) also completed an ADE interview. Baseline STOPP PIP prevalence was 40% and 445 (74%) patients reported ≥1 ADE at follow-up. In multivariable analysis, ≥2 STOPP PIP was associated with ADEs (adjusted incidence rate ratio: 1.29 [95% CI 1.03, 1.85; p = .03]; poorer health related quality of life [adjusted regression coefficient: -0.11 [95% CI -0.16, -0.06; p < .001]]; and, ≥1 accident & emergency visit [adjusted OR: 1.85 [95% CI 1.06, 3.24; p = .03]]). Baseline Beers 2012 prevalence was 26% and there was no association with adverse health outcomes in multivariable analysis.

CONCLUSIONS: Older community-dwelling people, prescribed ≥2 STOPP PIP are more likely to report ADEs, poorer health related quality of life and attend the accident & emergency department over 2-year follow-up.