[Chronic widespread pain and tender points in low back pain: a population-based study]

Clinical observation suggests a frequent coincidence of back pain (BP) and fibromyalgia (FMA). Based on data from a population survey on back pain we studied the hypothesis of FMA being a frequent underlying condition of BP. We additionally studied the association of the severity of back pain and both chronic widespread musculoskeletal pain and active tender points.

Data from a regional two-stage survey on urban German residents (aged 25-74 years) of Luebeck/Northern Germany (N=3969) were reanalyzed. The survey combined a postal questionnaire screening with a subsequent medical-psychological examination. Only subjects with back pain on the day of filling in the questionnaire were invited (n = 875). The response and participation rates were 82% and 73%, respectively. The severity of back pain was graded according to Kohlmann and Raspe (1994; based on pain severity and disability). In assessing widespread pain and tender points and classifying FMA-cases, we followed the criteria of the American College of Rheumatology (Wolfe et al. 1990). Standardized psychometric scales were used to measure general health status, bodily complaints, depressiveness, and catastrophizing cognitions.

In Luebeck, the overall point prevalence of back pain reached 39%. Among those invited and examined we found 27%, 25%, and 19% with back pain grade 1, 2 or 3, respectively. 29% reported no back pain on the day of examination. 12.6% of probands with actual back pain reported chronic widespread pain. The number of active tender points showed a significant and relevant association with back pain grade and was additionally correlated with all indicators of somatic and psychological distress.

Our data do not support the hypothesis of FMA as a frequent underlying condition of BP. We found, however, a close correlation between BP grade (and amount of distress) and tender points count. More severe forms of BP imply an increasing allodynia/hyperalgesia, itself being associated with a higher amount of somatic and psychological distress (Chronic severe) back pain seems to be more than simply pain in the back.