Clinical outcomes and healthcare utilization in very elderly patients with pneumonia: an analysis of korean national health insurance claims database.

Pneumonia remains a major cause of morbidity and mortality worldwide, particularly among the elderly. As populations age rapidly, the disease burden increasingly concentrates in the very elderly, yet evidence specific to this group remains limited. Our study aimed to compare recent trends in pneumonia incidence and clinical outcomes between the elderly and the very elderly. This retrospective cohort study used Korea's nationwide health insurance claims database. Elderly patients aged ≥ 65 years who were hospitalized due to pneumonia between 2009 and 2019 were identified. Individuals older than 80 years were further categorized into the very elderly group (≥ 80 years). After 1:1 propensity-score matching, pneumonia-related clinical outcomes were analyzed using generalized linear models and Cox proportional hazard regression models. Among 889,174 elderly pneumonia patients hospitalized from 2009 to 2019, 423,110 (47.6%) were the very elderly group, with their proportion incrementally increased during that period. After 1:1 matching, a total of 444,788 patients were observed. The very elderly group had greater healthcare utilization, including pneumonia-related hospitalizations (incidence rate ratio [IRR] = 1.92), emergency visits (IRR = 1.99), intensive care admissions (IRR = 2.29), longer hospital stays (IRR = 2.41; all p-value < 0.001), and higher mortality (hazard ratio = 2.47, p-value < 0.001). Rehospitalization incidence rose from 28.6 to 49.2 per 100 person-years in the elderly and from 59.2 to 84.1 in this population, who consistently showed higher rates throughout the study period. The proportion of very elderly patients with pneumonia has increased rapidly, with markedly worse outcomes and higher rehospitalization rates. These findings underscore the need for age-specific strategies incorporating geriatric and palliative care to reduce the growing clinical burden in this population.