Association between potentially inappropriate medications and 30-day outcomes among hospitalized older adults with reduced physiologic reserve: a retrospective cohort study.

Objectives: To investigate the independent effect of potentially inappropriate medications (PIMs) on 30-day adverse post-discharge outcomes (unplanned readmissions or emergency department [ED] visits) among hospitalized older adults after strictly controlling for confounders, such as polypharmacy and psychological comorbidities, and to identify high-risk phenotype in patients with reduced physiologic reserve and specific drug classes associated with adverse outcomes. Methods: This retrospective cohort study included 1,264 older patients (aged ≥65 years). PIMs were identified at discharge. Multivariable Cox regression and 1:1 propensity score matching (PSM, caliper 0.02) were used to adjust for confounders, including medication count and psychological comorbidities. Sensitivity, subgroup, drug-specific, and E-value analyses were performed to assess risk heterogeneity and robustness. Results: Overall, 41.8% of the patients (n = 529) were exposed to PIMs. PIM status was not significantly associated with the 30-day composite outcome (unplanned readmission or ED visits) in either the total population (n = 1,264; adjusted hazard ratio [AHR] 1.22, 95% confidence interval [CI] 0.92-1.62, Conclusion: After controlling for polypharmacy, PIM was not a uniform predictor of the 30-day composite outcome, but it served as a marker of clinical complexity. However, it became a significant marker of risk in patients with reduced physiologic reserve and in those with inappropriate PPI use. Clinical interventions should prioritize these high-risk phenotypes for precision deprescribing.