The purpose of this study was to investigate the associations of numbers of comorbidities with critical type and death of COVID-19. Results suggest that patients with more comorbidities have higher risk of critical type and death compared to patients without comorbidities.
Based on our analysis, COVID-19 patients with single NCD such as respiratory diseases and hypertension tent to get more severe outcomes when compared to the non-comorbidity population. But other single NCD didn’t show the significant effects. This suggests that basic diseases of respiratory system or hypertension might cause more serious damage to lung function compared to other systemic diseases. Previous studies indicated that these two diseases especially hypertension got high incidence in patients with COVID-19[12, 13]. Control and treatment of related diseases may be important factors in preventing disease progression to critical type or even death.
As the results shown, the risk of critical type and death of SARS-COV-2 infected patients is obviously affected by the numbers of comorbidities. Patients of COVID-19 with two or more comorbidities have not only a nearly four-fold increasing risk of death, but also much higher risk of critical type than that of patients without comorbidities, regardless of the types of NCDs. These findings suggest that patients with two or more NCDs are a much more vulnerable population in the current COVID-19 outbreak. It seems advanced age is one of the explanations as elder patients tend to have more NCDs simultaneously in our results . However, patients with two or more comorbidities also have significant results on risk of critical type after adjusting for age and gender. Other possible reasons should be discussed to explain the mechanism.
Recent studies suggested that viral susceptibility in patients with NCDs may be associated with a low immune response[15, 16]. Changes in immune system activity have been identified as a hallmark feature of many NCDs, including type 2 diabetes mellitus, atherosclerosis and cancer[17, 18]. Patients with NCDs often get broken homeostatic immune response and decrease in regulatory T cells[18–20]. So immunological response might not be generated such effectively to defend attack of virus in patients with NCDs compared to normal population. Abnormalities of immune function and subsequent systemic inflammation might become significant risk of critical type and death for COVID-19 patients with NCDs. However, significant results only shown between the two-comorbidity group with the non-comorbidity group. It could not be excluded that there are synergistic effects between different kinds of chronic diseases which magnified the risk of immune abnormalities. These results performed a simpler way of prognosis evaluation for COVID-19 patients that the presence of two or more comorbidities portended a high risk of critical type or mortality.
According to the model after adjusting for age and gender, patients with two or more comorbidities have no significant results on risk of death, but the P value is close to 0.05. The reason leading to such results might be the small sample size[21, 22]. In spite of no significant results between the one-comorbidity group with the non-comorbidity group, we cannot rule out there might be a weak risk which didn’t found due to limitations of research size either. Cohort with larger sample will be needed to verify the results and get more realistic risk about critical type and death.
Several limitations of this study should be considered when interpreting the results. First, the sample size of COVID-19 patients included in our study is small and limited in one area, larger scale national or even international level collaborated research will be necessary to further studies. Second, the varieties of comorbidities included in our study were limited, and the associations might be influenced by other kinds of comorbidities which may not be captured. Last, missed diagnosis of comorbidities might be existed and made influence to the results.
Despite these limitations, this study has noticeable strength. This study was the first report that investigated the associations of comorbidities with the risk of critical type and death of COVID-19. Understanding these associations is essential, because these may further reminder us paying attention and managing the risk of comorbidities in the treatment of COVID-19. We hope our report will provide the needed information that will benefit global patients.