Sex differences in claudication pain in subjects with peripheral arterial disease

Purposes: To compare the claudication distances between men and women patients with peripheral arterial disease (PAD), and to determine whether sex differences in claudication pain persisted after controlling for potential confounders such as demographic, functional, and physiological measures. Methods: A total of 488 men and 72 women functionally limited by intermittent claudication were evaluated. Patients were characterized on PAD-specific measures consisting of ankle/brachial index (ABI) and treadmill claudication distances, physical function measures consisting of ambulatory function, monitored physical activity, balance, and strength, and demographic measures obtained during a medical history. Results: Initial claudication distance (ICD) was 33% shorter (P = 0.024) in women than in men (126 +/- 22 vs 189 +/- 13 m; mean +/- SEM), and absolute claudication distance (ACD) was 23% shorter (P = 0.022) in women (313 +/- 43 vs 407 +/- 18 m). These differences were present despite similar (P = 0.440) ABI values between women (0.63 +/- 0.02) and men (0.62 +/- 0.01). Peak oxygen uptake (P = 0.043) and self-perceived stair climbing ability (P = 0.020) were different between men and women, and were independently related to ICD (multiple R = 0.57, P < 0.001) and to ACD (multiple R = 0.7 1, P < 0.001). The sex differences in ICD (P = 0.524) and ACD (P = 0.722) were no longer present after controlling for peak oxygen uptake and self-perceived stair climbing ability. Conclusion: Shorter treadmill claudication distances in women with PAD were explained by their lower cardiopulmonary fitness and poorer 'self-perceived ability to climb stairs than compared with men. Therefore, women with intermittent claudication represent a subgroup of PAD patients who should receive high priority for exercise rehabilitation to improve physical function.