The Clinical Characteristics and Risk Factors of Severe COVID-19

Objective: We aim to investigate the clinical characteristics and risk factors for the severe cases of coronavirus disease 2019 (COVID-19) in comparison with the non-severe patients. Methods: We searched PubMed, EMBASE, Web of Science, and CNKI to collect all relevant studies published before July 26, 2020, and a total of 30 papers were included in this meta-analysis. Results: In the severe COVID-19 patients, 60% (95% CI = 56–64%) were male, 25% (95% CI = 21–29%) were over 65 years old, 34% (95% CI = 24–44%) were obese, and 55% (95% CI = 41–70%) had comorbidities. The most prevalent comorbidities were hypertension (34%, 95% CI = 25–44%), diabetes (20%, 95% CI = 15–25%), and cardiovascular disease (CVD; 12%, 95% CI = 9–16%). The most common blood test abnormalities were elevated C-reactive protein (CRP; 87%, 82–92%), decreased lymphocyte count (68%, 58–77%), and increased lactate dehydrogenase (69%, 95% CI = 57–81%). In addition, abnormal laboratory findings revealing organ dysfunctions were frequently observed in the severe cases, including decrease in albumin (43%, 95% CI = 24–63%) and increase in aspartate aminotransferase (47%, 95% CI = 38–56%), alanine aminotransferase (28%, 95% CI = 16–39%), troponin I/troponin T (TnI/TnT; 29%, 95% CI = 13–45%), and serum Cr (SCr; 10%, 95% CI = 5–15%). Conclusion: The male, elderly and obese patients and those with any comorbidities, especially with hypertension, diabetes, and CVD, were more likely to develop into severe cases. But the association between hypertension, diabetes, CVD, and severity of COVID-19 was declined by the increase of age. A significant elevation in cardiac TnI/TnT, the hepatic enzymes, and SCr and the reduction in lymphocytes with elevated CRPs are important markers for the severity. Specific attention should be given to the elderly male and obese patients and those with indications of severe immune injury in combination with bacterial infection and indication of multi-organ dysfunction or damages.