Is hormone replacement therapy a risk factor for low back pain among postmenopausal women?

Study Design, Cross-sectional study with two age cohorts. Objective. To assess whether women receiving hormone replacement therapy after menopause have a higher prevalence of back problems than women who do not receive such treatment. Background. Back pain is a common medical problem: throughout life and especially during pregnancy. Hormonal factors have been proposed as a possible contributor. Patients and Methods. A validated postal questionnaire was sent in early 1995 to all 1324 women of 55 years and 56 years of age residing in Linkoping, Sweden. This questionnaire included questions about current rent hormone replacement treatment, previous and current back problems, medical care for back problems, parity, exercise and smoking habits, and occupation. Results. The questionnaire was returned by 84.7% of the women. There was a significant, albeit weak, positive association between current use of hormone replacement treatment and low back pain. Previous back problems during pregnancy was a strong risk factor for current back pain, whereas neither current smoking nor regular physical exercise was a risk factor according to multiple logistic regression analysis. The interaction of smoking and an occupation involving heavy lifting significantly affected back pain. Conclusions. Women receiving hormone replacement treatment had a slightly, but significantly, higher prevalence of current back pain than nonusers (48% vs. 42%, respectively, P < 0.05), which could not be explained by differences in occupation, smoking habits, or current physical activity. Although the association be-tween hormone replacement therapy and back problems is weak and probably of minor clinical importance, it is speculated that hormonal effects on joints and ligaments may be involved.