In a study of patients in China, investigators found most men were more likely than women to have severe cases of COVID-19, and more likely to die from the disease.
Being elderly and having a weakened immune system have already been shown to be risk factors of more severe coronavirus disease 2019 (COVID-19), but new research suggests another risk factor might be gender.
The study, published in Frontiers in Public Health, found that men were more likely to have serious cases of the disease than women, and men had nearly 2.5 times the death rate of women.
Jin-Kui Yang, MD, PhD, of Beijing Tongren Hospital, in China, said the research was prompted by observations at his hospital early in January that male patients seemed to be dying more than female patients.
"This raised a question: are men more susceptible to getting or dying from COVID-19?” Yang explained. “We found that no-one had measured gender differences in COVID-19 patients, and so began investigating.”
The result of that investigation shows that while the prevalence of the disease appears to be the same in both females and males, men are significantly more likely to die if they become infected with SARS-CoV-2. If replicated in other areas, these findings could have implications for how patients are treated and risk-stratified.
The study is based on 43 hospitalized patients treated by Yang and his co-authors, a public data set including the first 37 patients who died from COVID-19 and 1019 patients who survived, as well as data from 524 patients who became infected with the SARS virus in 2003. Of the latter group, 139 patients died.
Gender differences were observed in all 3 data sets, and in all 3 cases it was male patients who experienced more serious disease. In the largest of the 2 COVID-19 data sets, 70% of the deaths were men.
The reasons for the correlation between the male gender and more severe disease are not clear. However, Yang and colleagues posit that one factor could be ACE2, the protein to which the COVID-19 and SARS viruses attach.
“We have previously reported that high protein expression of ACE2 receptor in specific organs correlated with specific organ failures, indicated by corresponding clinical parameters in SARS patients,” Yang and colleagues write. “It has been shown that circulating ACE2 levels are higher in men than in women and in patients with diabetes or cardiovascular diseases.”
Patients with diabetes and cardiovascular disease are also believed to have a higher risk of death from the novel coronavirus.
Though the data included in the study showed a significant disadvantage for men who contract the virus, the investigators said these data are preliminary and will need to be replicated with larger data sets.
Yang and colleagues note that they had to base their severity-of-disease analysis on just the 43 patients at their hospital, since they did not have access to sufficient patient information to parse the other data sets. A larger dataset was used for the analysis of COVID-19 deaths.
“More clinical and basic research regarding gender and other prognostic factors for individualized assessment and treatment is needed in the future,” they concluded.