PREVALENCE OF FIBROMYALGIA IN CHILDREN - A CLINICAL-STUDY OF MEXICAN CHILDREN

Objective. To determine the prevalence of fibromyalgia (FM) in schoolc hildren according to the 2 stage classification process proposed by th e 1990 American College of Rheumatology (ACR) Multicenter Criteria Com mittee on Fibromyalgia. Methods. Stage 1: we administered a pain quest ionnaire to a sample of 548 schoolchildren (264 boys, 284 girls; mean age 11.9 yrs, range 9-15). Stage 2. two rheumatologists examined all c hildren with diffuse pain. Using thumb palpation, they examined 18 fib romyalgia tender points and 3 pairs of controls points followed by dol orimetry. Additionally, a random sample of 79 children with no pain we re selected as controls, following the same procedures (thumb palpatio n and dolorimetry). The Wilcoxon test was used to compare the distribu tion of tenderness thresholds between FM and non-FM groups. Kappa stat istics for multiple raters was used to assess interobserver agreement. Results. Seven children, all girls, fulfilled the ACR diagnostic crit eria for FM. Thus, the prevalence of FM in this group of schoolchildre n reached only 1.2%. The girls with FM had a mean of 14 tender points, whereas controls (n = 79) had 2.4. Pain thresholds were 3.4 kg in chi ldren with FM and 5.1 kg in controls (p = 0.004). Conclusion. The prev alence of FM in our study was 5-fold lower than a previous report. Thi s variance may be due to (1) racial and sociocultural differences betw een populations; and (2) differences in methodological approach. The d ifficulties of making accurate estimates of FM across different studie s are highlighted.