Potentially inappropriate medicines in a cohort of community-dwelling older people in New Zealand

Aim: To examine independent factors associated with potentially inappropriate medicines (PIM) among 316 community-dwelling people aged ≥75 years living in Dunedin. Methods: People aged ≥75 years living in the community in Dunedin, New Zealand, taking ≥1 prescription medicines, randomly sampled from the electoral roll, were interviewed about their medicine-taking practices. A medication inventory comprising prescription and non-prescription medicines was taken from each participant at the time of the interview. Participants used a median of seven prescription medicines (range 1-19) and one non-prescription medicine (0-14). PIM were identified using the updated 2012 Beers criteria. Results: PIM were identified in 42.7% (n=135) older people. A total of 23 (7.2%) took two PIM, five (1.5%) took three PIM, four (1.2%) took four PIM and one (0.3%) took five PIM. Of the 184 total PIM identified, the top three drug classes were non-COX-selective non-steroidal anti-inflammatory drugs (24.0%), tricyclic antidepressants (16.8%) and benzodiazepines (14.6%). Polypharmacy (adjusted odds ratio [OR] 2.06, 95% confidence interval [CI] 1.03-4.12) and the use of any psychotropic drug use (OR 22.05, 95% CI 5.80-83.84) were associated with PIM exposure. In the Poisson regression model, the risk of taking a PIM significantly decreased with age (OR 0.95, CI 0.91-0.99) and increased as the number of drugs prescribed increased (OR 1.11, CI 1.08-1.15). Conclusion: The prevalence of PIM is relatively high in community-dwelling older people aged ≥75 years living in New Zealand. PIM defined by the Beers criteria might be a useful initial screening tool, before efforts to stop unsafe medication use or replace with safer alternatives are initiated.