Association of Social Determinants, Multimorbidity, and Functional Status with Mortality after Pneumonia

Social support, multimorbidity, and functional status are important determinants of health in older adults, but their prognostic implications remain unclear after an acute illness. We conducted a prospective cohort study of 201 patients 65 years or older who were hospitalized for pneumonia at a university hospital in Korea in 2019-2020. K-means cluster analysis was performed using social deprivation score (range: 0-5), activities of daily living (range: 0-7), instrumental activities of daily living (range: 0-7), physical limitation score (range: 0-7), and Gagne comorbidity index (range: 0-24) (higher scores indicate higher risk). Four groups were identified: 1) Group A: physically limited and non-disabled group with limited social support; 2) Group B: multimorbid but functional group with social support; 3) Group C: multimorbid and disabled group with social support; 4) Group D: multimorbid and disabled group with limited social support. For Groups A through D, the Kaplan-Meir estimates for 6-month mortality were 10.0%, 18.0%, 34.2%, and 43.6%, respectively, and the 6-month mean survival times were 166.4 days (95% CI: 156.1-176.6), 156.9 days (95% CI: 140.8-173.1), 145.2 days (95% CI: 126.6-163.8), and 125.9 days (95% CI: 107.7-144.1), respectively. After adjusting for sex, age, and pneumonia severity score, the hazard ratios for Groups B through D versus Group A were 2.07 (95% CI: 0.70-6.13), 3.14 (95% CI: 1.17-8.42), and 4.38 (95% CI: 1.73-11.04), respectively. Our results suggest that multimorbidity and disabilities were implicated in higher risk of 6-month mortality after pneumonia, and social support may mitigate this risk among those with multimorbidity and disability.