Early reports from China found that both established cardiovascular disease and its risk factors, such as hypertension and diabetes mellitus, were common pre-existing conditions in patients with COVID- 19. The high prevalence of these comorbidities was confirmed in subsequent studies. Remarkably, the prevalence of these pre-existing conditions was higher in critically ill patients and in those who died. In the analysis performed by Wu and McGoogan, including 44 672 patients with confirmed COVID-19, the overall case fatality rate was 2.3%, and increased with comorbid conditions: 10.5% for cardiovascular disease, 7.3% for diabetes, and 6% for hypertension. The connections between cardiovascular disease, hypertension, age, and vascular aging are complex. The association between hypertension and COVID-19 mortality or severity could be explained in part by the increased age and higher prevalence of cardiovascular disease, both well-known risk factors for mortality in critical patients.
Therefore, in order to identify independent predictors of COVID-19 mortality or severity, models should be properly adjusted to exclude potential confounding effects.