Sex difference in response to cardiopulmonary exercise testing in patients with chronic obstructive pulmonary disease

Background: Cardiopulmonary exercise testing is an important clinical tool to evaluate exercise capacity and to predict the outcome in patients with chronic obstructive pulmonary disease (COPD). Aim: To evaluate exercise tolerance and pulmonary function in COPD patients in relation to sex. Patients and methods: This prospective cross‑sectional analytic study has been conducted in Assiut University Hospital, Chest Department from May, 2017 to January, 2019. Sixty patients with clinical and functional diagnosis of COPD were subjected to: baseline dyspnea assessment assessed by modified Medical Research Council and COPD assessment test, arterial blood gas analysis preexercise and postexercise, pulmonary function test, and cardiopulmonary exercise testing. The patients were divided into two groups: each group included 30 men and 30 women. Results: There were no significant differences between both sexes in response to exercise with the exception of significantly higher oxygen consumption (VO2% predicted) in men (in men = 49.53 ± 9.08, in women = 44.83 ± 7.60, P = 0.03) and that women had significantly higher lactate threshold than men (lactate threshold = 55.46 ± 5.32 and 50.57 ± 7.74, respectively, P = 0.02). Female patients had significantly lower breathing reserve and significantly lower respiratory frequency (P 0.001). Male patients had significantly lower heart ratemax, and significantly higher heart rate reserve than women (P 0.001 and 0.04, respectively). Conclusions: There were no significant differences between both sexes in response to exercise except that men with COPD had significantly higher oxygen consumption and exercise capacity (peak VO_2) than women with COPD.