Sex-related influences on pain: A review of mechanisms and clinical implications.

Abstract

Objective: To review the literature regarding gender-related influences on the experience of pain. Methods: Medline searches and reference lists were used to locate published articles regarding gender differences in pain. Results: Women are at increased risk for many clinical pain conditions and for increased severity of clinical pain relative to men. Women typically report lower pain threshold and tolerance and higher pain ratings than men in laboratory research. Contributing factors include sex hormones, pain modulatory systems, family history, stereotypic sex roles, and affective/cognitive factors. Conclusions: The clinical implications of gender differences in pain responses are discussed, including gender differences in pain treatment outcomes. Gender-related factors affect pain considerably and merit additional attention in pain research and treatment. Pain is associated with many conditions for which individuals seek rehabilitation, and rehabilitation interventions are often accompanied by pain. Indeed, pain is sometimes conceptualized as both an impediment to and an indicator of progress (e.g., “No pain, no gain”). Thus, an understanding of individual difference factors that influence pain is important in the rehabilitation setting. Pain is a complex experience sculpted by multiple biological, psychological, and sociocultural forces. Sex (i.e., the biological classification of male vs. female) and gender (i.e., one’s selfrepresentation of being male or female that is based on both sex and social considerations) recently have received increasing attention as individual difference variables that influence pain. Understanding the influence of gender is particularly relevant in the rehabilitation setting because the prevalence of disability is greater among women than men (Leveille, Penninx, Melzer, Izmirlian, & Guralnik, 2000; Leveille, Resnick, & Balfour, 2000), and disability specifically associated with pain is more frequent among women (Rethelyi, Berghammer, & Kopp, 2001). Moreover, several painrelated conditions common in rehabilitation settings show gender differences in prevalence, including rheumatoid arthritis, osteoarthritis (Buckwalter & Lappin, 2000; Verbrugge, 1995), and multiple sclerosis (Duquette et al., 1992), which are more common among women, and spinal cord injury (Nobunaga, Go, & Karunas, 1999), which occurs more frequently in men. The purpose of this review is to discuss the influence of gender on pain responses. First, the nature of gender differences in pain responses is presented. Then, potential mechanisms underlying these effects are reviewed, and the clinical implications for pain management are then explored.