Disabling musculoskeletal pain and its relation to somatization: a community-based postal survey

Background Somatization (a tendency to report distress from somatic symptoms) is a little studied, but potentially important, confounder and effect modifier in occupational studies of musculoskeletal disease. Aims To assess the role of somatization as a risk factor for disabling regional pain. Methods A questionnaire was mailed to 4998 subjects of working age. Questions were asked about chronic and disabling pain in the past 12 months affecting the arm, low back, knee or combinations of these sites. Distress from physical symptoms was assessed using elements of the Brief Symptom Inventory and mental well-being was assessed using the short-form 36 (SF-36). Associations were examined by modified Cox regression and expressed as hazard ratios (HRs) with 95% confidence intervals (CI). Results Among 2632 responders, 24% reported chronic pain and 25% disabling pain at one or several sites. Risk of chronic or disabling pain increased strongly according to the number of somatic symptoms reported as bothersome. For example, the HR for chronic upper limb pain in those distressed by >= 2 somatic symptoms in the past 7 days versus none was 3.9 (95% CI 2.9-5.3), and that of disabling upper limb pain was 5.8 (95% CI 4.1-8.3). Similar patterns were found for the low back and knee, and there was a gradient of increasing risk according to the number of sites with disabling pain. In comparison, associations with SF-36 mental well-being score were weaker. Conclusion Somatizing tendency should be evaluated as a possible confounder or effect modifier in studies of occupational risk factors for musculoskeletal pain.