Healthcare and cost burdens associated with potentially inappropriate medication use in older adults: a matched cohort study

Abstract Background The adverse effects of potentially inappropriate medications (PIMs) use in older adults are one of major public health burdens. This study aimed to examine the association between PIM use and healthcare utilizations and costs among older adults. Methods We used the Korean National Health Insurance Service-Elderly Cohort Database in 2015–2018 with matched cohort design. A propensity score derived from 16 variables, including age, sex, index year, Charlson Comorbidity Index scores, income decile, residential status, nine main comorbidities and number of comedication, was used for 1:1 matching. Cox proportional hazards regression was used to compare the risk of hospitalization and emergency department (ED) visits 1 year after the index date between PIM users and non-users. In addition, hospitalization- and ED visit related costs were evaluated using a two part model consisting of logistic regression and generalized linear model with logit link. Results A total of 3,896 older adults aged ≥ 65 years at index date were included, comprising 1,948 PIM users and 1,948 matched non-users. All the matching variables were well balanced with absolute Standardized Mean Difference (aSMD) < 0.1. Females were 52.77% in non-users and 54.65% in users. The mean age was 73.26 (sd: 5.97) in non-users and 73.14 (sd: 5.98) in users. The results indicated that PIM users were associated with higher risk of hospitalization than non-users (adjusted HR [aHR]: 2.18, 95% CI: 1.81–2.63) and were more likely to visit the ED (aHR: 3.08, 95% CI: 2.01–4.72). Furthermore, the total healthcare costs for PIM users were 40% higher among PIM users than non-users (adjusted Cost Ratio [aCR]: 1.4, 95% CI: 1.35–1.54). Among PIM users, increasing numbers of PIMs were associated with higher total healthcare costs, as well as higher hospitalization- and outpatient-related costs. Conclusion PIM use was associated with an increased risk of hospitalization and ED visits, as well as higher healthcare costs. These findings highlight the importance of regular medication review and optimization of prescribing in older adults. However, PIM use should be considered within the broader context of multimorbidity and frailty, rather than as an isolated risk factor, when developing strategies to improve health outcomes in this population.