Potentially inappropriate medication at polypharmacy initiation in adults aged ≥ 45 years: a nationwide descriptive cross-sectional study

Although polypharmacy and potentially inappropriate medications (PIMs) have been well described, the initiation of polypharmacy and the contribution of PIMs at the time of initiation remain poorly documented. We aimed to describe new polypharmacy users and identify the medications contributing to its initiation. In this descriptive cross-sectional study, we identified all incident cases of polypharmacy in 2024 among individuals aged ≥ 45 years using the French national health database (SNDS). Incident polypharmacy was defined as the overlap of five distinct ATC-5 medications on a day, with no polypharmacy in preceding five years. Medications dispensed at polypharmacy initiation were classified as PIMs or not according to PROMPT criteria (45–64 years old) and REMEDI[e]S criteria (≥ 65 years) excluding duration- or dose- based criteria. Among 693 309 individuals initiating polypharmacy, 71.1% were aged < 65 years. Among individuals aged 45–64 years, 16.2% had ≥ 1 PIM at polypharmacy initiation. Among these individuals, the most frequent PIMs were opioids without laxatives (75.6%) and first-generation antihistamines (22.3%). Among individuals aged ≥ 65 years, 13.0% had ≥ 1 PIM; the most frequent were statins and antiplatelet agents for primary prevention of cardiovascular events (40.4% and 19.6% respectively), and 30.4% had ≥ 2 PIMs. Individuals exposed to ≥ 1 PIM were more often male (56.5% vs. 50.2%) and received more medications at polypharmacy initiation (median 5 vs. 3) than those non-exposed. Polypharmacy initiation may coincide with prescriptions that meet PIM criteria, highlighting this moment as a key opportunity for medication review.