Chronic pain conditions in women.

There are inconsistent data on the age/sex prevalence pattern of back pain and on chest pain. However, it is possible that for chest pain, the rates are higher in younger women and older men. Neck pain, joint pain, and fibromyalgia all appear to increase with age in both genders, whereas abdominal pain and tension-type headaches decrease with age, and migraine headache and TMD appear to peak in the reproductive years. A concluding example illustrates how epidemiologic data can be used to enhance our understanding of the causes of pain. A higher prevalence in women and a peak prevalence during the reproductive years as seen in TMD suggest that either biologic or psychosocial factors unique to women in this period of life could increase the risk of developing or maintaining this pain. As female reproductive hormones can play a role in migraine, at least for some women, it would be interesting to examine whether hormones play a role in TMD. The situation that occurs when menopause is followed by hormone replacement therapy (HRT) provides a natural experiment similar to a laboratory experiment in which female animals are deprived of the natural sources of hormones and then hormones are replaced exogenously. In women, of course, the decision to receive HRT may be associated with a number of psychosocial variables that might also influence pain. Recognizing these limitations, data from records of a large health maintenance organization were examined to ascertain whether use of estrogen or progestin (or both) in postmenopausal women might be associated with the occurrence of TMD pain and, thus, whether the hormone hypothesis might be worthy of further investigation. More women with TMD than controls used estrogen replacement therapy, and slightly more patients than controls used progestin. The use of estrogen significantly increased the odds of having TMD. Progestin use showed a weaker association, which did not hold up after other factors were controlled. However, the risk of TMD appears to increase with increasing doses of estrogen. A review of the epidemiologic literature indicates that there are definite age and sex differences in the prevalence of many chronic pain conditions. There is little basic information about the source of these differences, such as different onset rates, different probabilities of recurrence, or different durations of pain, or combinations of these in women and men. Nevertheless, a systematic examination of the existing epidemiologic data may be an important step in helping pain researchers to generate hypotheses in the search for a better understanding of chronic pain in both sexes.