Assessment of nonarticular tenderness and prevalence of fibromyalgia in children.

Fibromyalgia syndrome (FS) is most common in midlife, but may be seen at any age. Its prevalence and assessment of tenderness in healthy children is not known. We assessed 338 healthy schoolchildren for tenderness thresholds and prevalence of FS. In all children a point count of 18 tender points (TP) was conducted by thumb palpation and tenderness of some of the TP sites as well as control point sites was further assessed using a Chatillon dolorimeter. All children and their parents were questioned about the presence of widespread pain or aching. Children were considered to have FS if they met the American College of Rheumatology (ACR) criteria for diagnosis of FS. Of the 338 children, 21 (6.2%) had FS. Thresholds of tenderness of 9 TP were 5.0 (1.2) (kg) [mean (standard deviation)] for boys vs 3.6 (0.8) (kg) for girls (p < 0.001). Thresholds of tenderness of the control point sites were 7.1 (1.4) (kg) for boys vs 5.5 (1.1) (kg) for girls (p < 0.001). Thresholds of tenderness of TP and control points in the children with FS were 2.5 (0.4) (kg) and 4.2 (0.5) (kg) vs 4.5 (1.2) (kg) and 6.6 (1.4) (kg) respectively in the children without FS (p < 0.001). We suggest that FS is common in the pediatric age group. Boys have lower tenderness than girls; children with FS have lower thresholds for tenderness both at control and TP compared to the subjects without FS.