Female Sex Affects Respiratory Function and Exercise Ability in Patients Recovered from COVID-19 Pneumonia

Background: Coronavirus-19 Disease (COVID-19) may cause persistent symptoms and functional respiratory impairment, known as long COVID. Determinants of long COVID are unclear. Although males experience more severe acute illness, the impact of sex on the occurrence of long-term sequelae is unknown. The aim of this study was to establish whether sex affects pulmonary function, exercise capacity, and clinical outcomes in patients recovered from COVID-19 pneumonia. Methods: We performed a retrospective analysis on patients evaluated in our "Post-COVID Clinic" after a median follow-up of 128 days from the acute disease. Tests performed included standard spirometry, diffusion capacity of the lung for carbon monoxide (DLCO), and 6-minute walk test (6-MWT). Results: A total of 157 patients (mean age 59.9 ± 12, 91 males) recovered from mild to severe pneumonia, without previous respiratory disease, were included. No differences in demographic data and in the severity of the acute illness were observed between the two study groups, males and females. Abnormal alveolar diffusion was more common and severe among females (DLCO <80% in 31% of males vs. 53% of females, p < 0.01; DLCO <70%, in 20% of males vs. 40% of females, p < 0.01). Severe reduction in 6-MWT was observed in 20% of males versus 46% of females (p < 0.01). Multiple logistic regression showed that female sex was an independent predictor of abnormal DLCO and 6-MWT. The prevalence of symptoms and radiological abnormalities was similar in the two groups. Conclusions: These data show that at 4 months follow-up women recovered from COVID-19 pneumonia are more likely to exhibit a reduced alveolar diffusion capacity and exercise tolerance than men, although a similar severity of the acute disease.