ABSTRACT
It has become increasingly clear that powerful interactive genetic, physiological, anatomical, neural, humoral, psychological, lifestyle, and sociocultural factors contribute to differences between males and females in pain and its relief. The words “sex” and “gender” have been used to describe these differences, sometimes interchangeably and at other times with a different interpretation. The definitions used in this chapter reflect a North American interpretation based on a consensus document (Level V evidence) (2). Sex is defined as the classification of living things generally as male or female according to reproductive organs and functions assigned by chromosomal complement. Gender is defined as a person’s selfrepresentation as male or female, or how that person is responded to by social institutions on the basis of the individual’s gender presentation. However, this apparent separation of sex and gender is artificial because they interact, influencing each other and changing across the lifespan of an individual. Acknowledging interactive sex-gender differences helps improve our understanding of multiple factors that can contribute to specific circumstances of pain, thereby improving and informing clinical diagnosis and treatment. In experimental studies of normal individuals, women report lower pain thresholds, higher pain intensities, and less pain tolerance (Level III evidence) (3). In epidemiological research, studies describe similar pain reports from women compared with men such that women experience higher pain severity of longer duration, of higher frequency and present in more sites (Level IVevidence) (4). In these population studies the sex prevalence rate of some painful disorders changes with age. Of those with higher female prevalence, abdominal pain had a higher rate in women than men at all ages despite declining steadily over the age of 40 years. This pattern was consistent across countries, towns, and small communities but excluded menstrual pain. Thus if specific gynecological or obstetric problems are included in this rate, female prevalencemay be increased further.
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