Our results showed that fatty liver is much more prevalent in COVID-19 patients, which is on par with other studies stating that fatty liver has a higher percentage among COVID-19 patients in comparison with non-COVID-19 patients (7, 12). The fatty liver prevalence among hospitalized COVID-19 patients is higher than the calculated prevalence of NAFLD in Iran from 2016 (37.84% vs. 33.95%). Other study findings state that increased liver fibrosis in NAFLD might affect COVID-19 outcome (3). Our result is also supported by Bramante et al. study indicating Fatty liver patients have a much higher risk of COVID-19 hospitalization; their study suggests metabolic syndrome and NAFLD/NASH available treatments significantly mitigated risks from COVID-19 those with home metformin glucagon-like-peptide 1 receptor agonist (GLP-1 RA) use has a non-significantly reduced odds of hospitalization(6).
Our study demonstrates that COVID-19 patients who suffer from fatty liver have to be hospitalized for more extended periods, which is confirmed by the study of Dong Ji and colleagues(12). The data analysis also shows that patients with fatty liver experience more severe symptoms during the course of the disease; the number of involved lobes and total involvement of lugs are higher in fatty liver patients, which can be attributed to the findings of the extended period of hospitalization data. A higher risk of disease progression is also suggested by another study that evaluated the disease severity by different factors(12), and another study also suggests fatty liver patients experience a more severe form of the disease(14).
In addition, the results suggest that social awareness should be gained regarding the negative impact of metabolic diseases such as fatty livers on patients with COVID-19 and that health policymakers should promote the use of preventive measures to prevent obesity and fatty liver.
With increased disease severity, the coronavirus disease 2019 mortality rate was expected to be noticeably higher among fatty liver patients. However, data analysis showed it could not be concluded that fatty liver is linked to a higher COVID-19 mortality rate, which is in contrast to another study that concludes liver injury is strongly associated with the COVID-19 mortality risk(6, 14).
According to our findings, the severity of COVID-19 is increased in Iran's autumn months, which is from September through October. It can be confirmed by other studies that suggest the emergence of virus mutations could have made the COVID-19 virus more transmissible and infectious (15). COVID-19 hospitalization length was not linked to autumn; however, it was much higher at the beginning of the COVID-19 pandemic; it can be speculated that patients used to be hospitalized for more extended periods because of not fully understood treatment and hospitalization protocols. We suggest coronavirus disease 2019 had higher severity in autumn; however, it should also be noted that during the autumn number of patients drastically increased; therefore, hospitals could only administrate patients with more severe symptoms. A newly conducted study also suggests that an increase in the number of COVID-19 patients and severity could be related to the decrease in the amount of individual vitamin D in the autumn and winter season (16). The previous studies give a clear understanding that there is an essential and direct role for vitamin D in modulating liver inflammation and fibrogenesis (17, 18). Other studies show a clear correlation between COVID-19 and vitamin D deficiency (19, 20), which indicates that treating fatty liver patients' vitamin D deficiency can reduce the chance of liver injury(20) and ultimately decrease coronavirus disease 2019 severity and mortality(6, 21).
According to our study and similar studies, the percentage of male patients is more significant than women in COVID-19 (22); our findings cannot validate the theory that male patients are also more prone to more severe forms of the disease, which is, in contrast, to study of Kuno et al.(23) Scatterplot Matrix data analysis showed that older adults are more susceptible to develop a more severe form of disease according to our data elderly patients have to hospitalized for more extended periods. The total score of lungs involvement is significantly higher, which is validated by previous studies; it can also be attributed to pre-existing illnesses (24). The elderly male mortality rate is higher than expected, and it is validated by other studies(25).
Deceased patients' data could only be collected from June through August and October through November of 2020, so the number of deceased patients could not be compared between different months of the year; the deceased patients' data was only used to compare mortality between the COVID-19 patients with and without fatty liver and if one sexuality has a higher risk of mortality. We did not have access to each patient's past medical history, so patients could not be accurately categorized into Non-alcoholic fatty liver disease patients; instead, the selected used term was fatty liver patients.