Impact of Potentially Inappropriate Prescribing on Adverse Drug Events, Health Related Quality of Life and Emergency Hospital Attendance in Older People Attending General Practice: A Prospective Cohort Study

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.