Studying sex and gender differences in pain and analgesia: a consensus report

Abstract

In September 2006, members of the Sex, Gender and Pain Special Interest Group of the International Association for the Study of Pain met to discuss the following: (1) what is known about sex and gender differences in pain and analgesia; (2) what are the "best practice" guidelines for pain research with respect to sex and gender; and (3) what are the crucial questions to address in the near future? The resulting consensus presented herein includes input from basic science, clinical and psychosocial pain researchers, as well as from recognized experts in sexual differentiation and reproductive endocrinology. We intend this document to serve as a utilitarian and thought-provoking guide for future research on sex and gender differences in pain and analgesia, both for those currently working in this field as well as those still wondering, "Do I really need to study females?"

Fig. 1

Patterns of estradiol, progesterone, and leuteinizing hormone (LH) in humans (a) and rats (b) during the reproductive cycle. Time unit of the x-axis in (a) is days; in (b), it is hours. Dark bars in (b) indicate dark period of the day/night cycle. Note that during the follicular phase in humans and its analog in rats (diestrus 2), 17β-estradiol rises but progesterone secretion remains low. After the LH surge, progesterone is elevated in both rats and women. In humans, the corpus luteum also secretes some 17β-estradiol, whereas in rats, during the brief luteal phase, 17β-estradiol concentrations decline. Reproduced from [17], with permission.

Fig. 2

The full cycle of translational research.