Why women are not small men: sex-related differences in perioperative cardiopulmonary exercise testing

The use of preoperative cardiopulmonary exercise testing (CPET) to evaluate the risk of adverse perioperative outcomes is increasingly prevalent. CPET-derived information enables personalised perioperative care and enhances shared decision-making. Sex-related differences in physical fitness are reported in non-perioperative literature. However, little attention has been paid to sex-related differences in the context of perioperative CPET.

We explored differences in the physical fitness variables reported in a recently published multi-centre study investigating CPET before colorectal surgery. We also report the inclusion rate of females in published perioperative CPET cohorts that are shaping guidelines and clinical practice.

We performed a post hoc analysis of the trial data of 703 patients who underwent CPET prior to major elective colorectal surgery. We also summarised the female inclusion rate in peer-reviewed published reports of perioperative CPET.

Fitness assessed using commonly used perioperative CPET variables-oxygen consumption at anaerobic threshold (AT) and peak exercise-was significantly higher in males than in females both before and after correction for body weight. In studies contributing to the development of perioperative CPET, 68.5% of the participants were male.

To our knowledge, this is the first study to describe differences between males and females in CPET variables used in a perioperative setting. Furthermore, there is a substantial difference between the inclusion rates of males and females in this field. These findings require validation in larger cohorts and may have significant implications for both sexes in the application of CPET in the perioperative setting.