Background: The pandemic of COVID-19 poses a challenge to global healthcare. The mortality rates of severe cases range from 8.1% to 38%, and it is particularly important to identify risk factors that aggravate the disease.
Methods: We performed a systematic review of the literature with meta-analysis, using 7 databases to identify studies reporting on clinical characteristics, comorbidities and complications in severe and non-severe patients with COVID-19. All the observational studies were included. We performed a random or fixed effects model meta-analysis to calculate the pooled proportion and 95% confidence interval (CI). Measure of heterogeneity was estimated by Cochran's Q statistic, I index and P value.
Results: A total of 4881 cases from 25 studies related to COVID-19 were included. The most prevalent comorbidity was hypertension (severe: 33.4%, 95% CI: 25.4%-41.4%; non-severe 21.6%, 95% CI: 9.9%-33.3%), followed by diabetes (severe: 14.4%, 95% CI: 11.5%-17.3%; non-severe: 8.5%, 95% CI: 6.1%-11.0%). The prevalence of acute respiratory distress syndrome, acute kidney injury and shock were all higher in severe cases, with 41.1% (95% CI: 14.1%-68.2%), 16.4% (95% CI: 3.4%-29.5%) and 19.9% (95% CI: 5.5%-34.4%), rather than 3.0% (95% CI: 0.6%-5.5%), 2.2% (95% CI: 0.1%-4.2%) and 4.1% (95% CI: -4.8%-13.1%) in non-severe patients, respectively. The death rate was higher in severe cases (30.3%, 95% CI: 13.8%-46.8%) than non-severe cases (1.5%, 95% CI: 0.1%-2.8%).
Conclusion: Hypertension, diabetes and cardiovascular diseases may be risk factors for severe COVID-19.