Incidence and impact of pneumonia on mortality among individuals with chronic noncommunicable diseases: a UK Biobank cohort study

Existing evidence has not comprehensively compared pneumonia incidence and subsequent outcomes in patients with specific conditions, including cardiovascular disease (CVD), chronic kidney disease (CKD), diabetes mellitus (DM), cancer and chronic obstructive pulmonary disease (COPD). Therefore, this study aims to investigate the incidence of pneumonia in patients with five major chronic noncommunicable diseases—CVD, CKD, DM, cancer, and COPD—and evaluate its impact on mortality and hospitalization. The incidence of pneumonia, the mortality before and after its onset, and hospitalization burden in the target populations were assessed using data from the UK Biobank cohort. Time-updated Cox regression models were used to estimate the risk of death following pneumonia, adjusting for a number of confounding variables. Total hospitalizations were analyzed by a semiparametric proportional rates model with rate ratios (95% CIs). The age-standardized incidence rate of pneumonia was highest in COPD patients (26.8 per 1,000 person-years; 95% CI: 24.5–29.5), followed by CKD (12.4 per 1,000 person-years; 95% CI: 11.3–13.7), CVD (10.1 per 1,000 person-years; 95% CI: 9.6–10.6), DM (8.4 per 1,000 person-years; 95% CI: 8.1–8.8) and cancer (6.3 per 1,000 person-years; 95% CI: 6.0–6.5). Following pneumonia, both mortality and hospitalization risks showed a marked increase. Patients with COPD had an adjusted hazard ratio (HR) of 8.15 (95% CI: 7.14–9.31) for all-cause death, while cancer patients faced nearly twice the risk (HR: 17.11; 95% CI: 16.04–18.24). The other study populations, including CVD, DM, and CKD, exhibited elevated risks in between. The risk of total hospitalizations was significantly increased, nearly doubling across all study populations. Pneumonia incidence is notably higher in patients with chronic diseases. An episode of pneumonia is linked to elevated risks of mortality and hospitalization.