The clinical burden of potentially inappropriate medications on hospitalization risk in an Italian older adult cohort: a large-scale real-world study.

INTRODUCTION: Optimizing drug treatments in older adults is essential for improving health outcomes and reducing drug-related issues. OBJECTIVE: This study aimed to develop an updated and comprehensive explicit indicator of potentially inappropriate medications in older adults, and to evaluate its association with all-cause hospitalization. METHODS: Administrative healthcare data from Local Health Units (LHUs) in Lombardy, Italy (2015-2018) were used to identify individuals aged ≥65 years who were exposed to potentially inappropriate medications (PIMs), identified through an explicit criteria-based list. Risk-set matching was used to select unexposed controls, and logistic regression models adjusted for high-dimensional propensity scores were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for all-cause hospitalization within 90 days after the first exposure date. KEY FINDINGS: Among 641 230 older patients, between 52.8% and 56.3% were exposed to at least one PIM. After matching (128 063 pairs) hospitalization rates were higher among the exposed (8.3%-10.2%) compared with the not exposed (5.1%-6.0%) across the LHUs. Pooled estimates showed an increased risk of hospitalization for those exposed (ORs 1.55, 95% CIs 1.48-1.62), with the highest risk observed in adults aged 65-74 years (1.67, 1.59-1.76) and in women (1.62, 1.55-1.70). CONCLUSIONS: Over half of older individuals were exposed to at least one PIM, with a 55% increase in short-term hospitalization risk. These findings highlight the urgent need for improved prescribing practices tailored to older populations.