Abstract
BACKGROUND: Lower respiratory tract illness (LRTI) is a significant cause of morbidity among adults, particularly older adults and adults with underlying medical conditions. Evidence on short- and long-term risks of mortality among adults requiring hospitalization or ambulatory care for LRTI, overall and within subgroups, is currently lacking. METHODS: A retrospective observational matched-cohort design and Optum's de-identified Clinformatics Data Mart Database (2012-2019) were used. The study population included adults who were hospitalized or received ambulatory care for LRTI and matched (1:1) comparison patients. All-cause mortality was ascertained during the 30-, 60-, 90-, 180-, and 360-day periods following the beginning of the LRTI episode. Risks of mortality were estimated for all LRTI patients and comparison patients as well as within age/comorbidity-specific subgroups. RESULTS: Among LRTI-hospitalized patients (n = 60.2K), 30-day mortality risk was 5.8% and 360-day risk was 18.3%, 7.5 and 2.6 times higher than corresponding values for comparison patients. Among LRTI-ambulatory patients (n = 2.4M), 30-day mortality risk was 1.2% and 360-day risk was 3.6%, 6.5 and 2.1 times higher than comparison patients. Among both LRTI-hospitalized and LRTI-ambulatory patients, mortality risk increased with increasing age and was higher for adults with chronic or immunocompromising conditions (vs without medical conditions). CONCLUSIONS: Short- and long-term mortality were higher among patients who were hospitalized or received ambulatory care for LRTI vs matched comparison patients, and risks increased markedly with increasing age and worsening comorbidity profile. Strategies for preventing LRTI, especially among persons at elevated risk, may reduce premature deaths and yield important public health benefits.