Polypharmacy, hospitalization, and mortality risk: a nationwide cohort study

Abstract

Polypharmacy is a growing and major public health issue, particularly in the geriatric population. This study aimed to examine the association between polypharmacy and the risk of hospitalization and mortality. We included 3,007,620 elderly individuals aged ≥ 65 years who had at least one routinely-prescribed medication but had no prior hospitalization within a year. The primary exposures of interest were number of daily prescribed medications (1-2, 3-4, 5-6, 7-8, 9-10, and ≥ 11) and presence of polypharmacy (≥ 5 prescription drugs per day). The corresponding comparators were the lowest number of medications (1-2) and absence of polypharmacy. The study outcomes were hospitalization and all-cause death. The median age of participants was 72 years and 39.5% were men. Approximately, 46.6% of participants experienced polypharmacy. Over a median follow-up of 5.0 years, 2,028,062 (67.4%) hospitalizations and 459,076 (15.3%) all-cause deaths were observed. An incrementally higher number of daily prescribed medications was found to be associated with increasingly higher risk for hospitalization and mortality. These associations were consistent across subgroups of age, sex, residential area, and comorbidities. Furthermore, polypharmacy was associated with greater risk of hospitalization and death: adjusted HRs (95% CIs) were 1.18 (1.18-1.19) and 1.25 (1.24-1.25) in the overall and 1.16 (1.16-1.17) and 1.25 (1.24-1.25) in the matched cohorts, respectively. Hence, polypharmacy was associated with a higher risk of hospitalization and all-cause death among elderly individuals.

Figure 1

Associations between the number of daily prescribed medications with the risk of (A) hospitalization and (B) mortality. All models were adjusted for age, sex, residential area, and Charlson comorbidity index score.

Figure 2

Subgroup analyses of the association between the number of daily prescribed medications and the risk of hospitalization. Subgroup analyses were performed and stratified by (A) age (65–69, 70–74, 75–80, and ≥ 80 years), (B) sex (men and women), (C) residential area (large city, small city, and rural area), and (D) comorbidity burden (CCI scores: 0, 1, 2, and ≥ 3). All models were adjusted for age, sex, residential area, and CCI score. CCI Charlson comorbidity index.

Figure 3

Subgroup analyses of the association between the number of daily prescribed medications and the risk of all-cause mortality. Subgroup analyses were performed and stratified by (A) age (65–69, 70–74, 75–80, and ≥ 80 years), (B) sex (men and women), (C) residential area (large city, small city, and rural area), and (D) comorbidity burden (CCI scores: 0, 1, 2, and ≥ 3). All models were adjusted for age, sex, residential area, and CCI score. CCI Charlson comorbidity index.