• Aili Wang, Kun Li, Hui Sun, Yuan Wang, and Huaie Liu.
• Department of Infectious Diseases, The First Affiliated Hospital, Kunming Medical University, Kunming, Yunnan Province, China.
• Medicine (Baltimore). 2025 Jan 31; 104 (5): e41360e41360.

AbstractOlder age and comorbidities are risk factors for increased coronavirus disease 2019 (COVID-19) severity, but few studies have explored their interaction. This study aimed to assess the actual impacts of these factors on disease severity in COVID-19. The enrolled COVID-19 patients were divided into 4 age subgroups (≤44, 45-59, 60-74, and ≥75 years). Logistic regression analysis was conducted to determine the association between comorbidities and disease severity; Kappa consistency test was implemented to verify the study results. Of the 1663 patients with COVID-19, 287 had severe disease. The disease severity was correlated with the age-adjusted Charlson Comorbidity Index in each age group. In the 4 subgroups, the odds ratio of age-adjusted Charlson Comorbidity Index declined with age. After removing age interference, diabetes and cardio-cerebrovascular diseases were the main risk factors for severe disease in patients aged <75 years, whereas only chronic lung disease was associated with disease severity in patients aged ≥75 years. When comorbidities alone were used to predict disease severity, only the predictions were consistent with real outcomes in patients aged ≥75 years, compared with the predictions of high-risk comorbidities mentioned in World Health Organization and Chinese guidelines (Kappa 0.106, P < .05). Although older age and comorbidities were risk factors for severe COVID-19, their effects on disease severity varied across age groups. Additionally, comorbidities had a greater impact on COVID-19 severity in younger patients.Copyright © 2025 the Author(s). Published by Wolters Kluwer Health, Inc.

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