Discussion
The most striking finding of our study was that the presence of metabolic syndrome significantly increased mortality in patients with COVID 19 pneumonia. Among comorbid conditions in COVID 19 patients, the highest mortality rates were observed in CAD (10.5%), diabetes mellitus (7.3%), chronic respiratory diseases (6.3%), hypertension (6.0%) and cancer (5.6%) patients11. In a recent study conducted on black COVID 19 patients, the presence of metabolic syndrome was shown to increase mortality, the need for intensive care and mechanical ventilation, but the presence of comorbidities associated with metabolic syndrome, such as hypertension and diabetes alone, were not related with it12. In another study involving 1870 patients, the presence of metabolic syndrome in COVID 19 patients increased mortality, the need for intensive care and mechanical ventilation. Among comorbidities associated with metabolic syndrome, diabetes was reported to increase mortality alone13. It is still unclear whether metabolic syndrome as a whole or its individual components increase this risk in COVID 19 patients. In our study, CAD, diabetes, hypertension, and hypertriglyceridemia were associated with increased mortality. However, metabolic syndrome was shown to increase mortality by 32.8 times. In addition, intensive care requirement and hospitalization were significantly higher in COVID 19 patients with metabolic syndrome.
In the literature, there are no studies regarding the effect of hypertriglyceridemia in COVID 19 patients, except in cases of hypertriglyceridemia secondary to tocilizumab, lopinavir and ritonavir therapy14. The mortality-increasing effect of hypertriglyceridemia found in our study may be parallel to the effect of coronary artery disease on mortality. In our study, since specific causes of death such as acute myocardial infarction and ischemic CV could not be verified, this finding could not be interpreted.
Although metabolic syndrome is more common in the elderly, mortality associated with metabolic syndrome decreases with age15,16. In many studies of COVID 19 patients, advanced age has been identified as the most important risk factor for increased mortality2,3,17,18. Similarly, in our study, the average age of patients with metabolic syndrome was higher and advanced age was associated with increased mortality.
Metabolic syndrome is one of the common comorbidities in patients with COPD. It is associated with physical inactivity and sedentary lifestyle, smoking and inflammatory cell activation in adipose tissue and lungs19,20. In many studies of COVID 19 patients, COPD has been identified as an independent risk factor that increases disease severity or mortality21,22,23. In our study, COPD was more frequent in COVID 19 patients with metabolic syndrome, and mortality rates were higher in patients with COPD.
The metabolic syndrome and aging is associated with a reduced cellular stress response that would make tissues more vulnerable to injury from Covid-19 increasing morbidity and mortality. Increased proinflammatory cytokines, such as IL-6 and TNF-α, in patients with metabolic syndrome are likely responsible for the development of diabetes, hypertension and coronary artery diseases, due to subclinical and persistent inflammation. This persistent inflammatory state causes an increase in acute phase reactants such as CRP, fibrinogen, and ferritin and is thought to worsen the clinical course of COVID 1924,25. In our study, COVID 19 patients with metabolic syndrome had lower oxygen saturations, higher CRP levels and more widespread radiological involvement at presentation compared to those without metabolic syndrome. High CRP levels and radiological weight score were associated with increased mortality. The worse clinical, laboratory and radiological values ​​at admission in COVID 19 patients with metabolic syndrome can be considered an indicator of the worsening of this constant and persistent inflammatory state with COVID 19 in the background.
The most important limitation of the study is that it is a retrospective study. Therefore, many patients had to be excluded because of lack of data for metabolic syndrome.