Medication Safety Gaps in Older Adults Across Outpatient and Inpatient Care in Peru: Evidence from Beers and STOPP/START Criteria

Background/Objectives: This study compared medication safety gaps across outpatient and inpatient care among older adults using explicit prescribing-quality criteria. Methods: We conducted an analytical cross-sectional study based on a retrospective review of 157 medical records from adults aged ≥ 60 years treated at Hospital Carlos Monge Medrano, a public referral hospital in Juliaca, Peru, in 2024. Stratified probability sampling included 73 outpatient and 84 inpatient records. Primary outcomes were Beers-defined potentially inappropriate medications, Screening Tool of Older Persons’ Prescriptions (STOPP)-defined potentially inappropriate prescribing, and Screening Tool to Alert to Right Treatment (START)-defined potential prescribing omissions. Overall medication safety gaps were assessed as a secondary exploratory composite outcome. Crude and adjusted prevalence ratios (PRs) with 95% confidence intervals (CIs) were estimated using modified Poisson regression with robust variance. Results: Overall medication safety gaps were identified in 79.0% of participants. START-defined omissions occurred in 52.9%, STOPP-defined inappropriate prescribing in 49.7%, and Beers-defined potentially inappropriate medications in 46.5%. Compared with outpatient care, hospitalization was associated with a lower prevalence of STOPP-defined inappropriate prescribing (adjusted PR = 0.74; 95% CI: 0.55–0.99) and a higher prevalence of START-defined omissions (adjusted PR = 1.39; 95% CI: 1.04–1.86). Polypharmacy and multimorbidity were independently associated with the composite outcome. Conclusions: Medication safety gaps were common but differed by care setting. Outpatient care showed more high-risk or insufficiently reviewed prescribing, whereas inpatient care showed more therapeutic omissions. These findings support prospective evaluation of medication review, reconciliation, deprescribing, and reassessment of omitted therapies in similar public referral settings.