PURPOSE: This study aims to estimate (i) the prevalence of potentially serious alcohol-medication interactions in a nationally representative sample of older adults using the Potentially Serious Alcohol-Medication Interactions in Older adults (POSAMINO) criteria, and (ii) whether POSAMINO prevalence changes over time.

METHODS: A prospective cohort study of adults aged ≥ 65 years, using data from the first three waves of The Irish Longitudinal Study on Ageing (TILDA). All 38 POSAMINO criteria were applied at each wave using respondents' information on regular medications and alcohol consumption. Multilevel logistic regression and negative binomial models were used to investigate whether the prevalence of POSAMINO varied over time.

RESULTS: The overall prevalence of POSAMINO was 18% at baseline, with 8% at risk of one potentially serious alcohol-medication interaction, and 10% at risk of two or more. The most common POSAMINO involved cardiovascular (CVS) agents (15% baseline; 11% wave 2; 14% wave 3), followed by central nervous system (CNS) agents (4% baseline; 4% wave 2; 5% wave 3). Prevalence of any POSAMINO (AOR 0.94, 95% CI 0.81, 1.08) or number of POSAMINO criteria (AIRR 0.97, 95% CI 0.91, 1.04) did not change over time. Any POSAMINO and number of POSAMINO were associated with younger age, male sex and number of medications and chronic conditions.

CONCLUSIONS: Potentially serious alcohol-medication interactions occurred in 18% of older adults in this study. Alcohol screening and brief interventions should be considered for high-risk groups at the point of prescribing, particularly among younger older adults, men and as patients receive more medications or develop additional illnesses.