To report our experience of fibromyalgia syndrome (FMS) in young children with onset at age 10 years and younger as compared to older children.
Clinical and laboratory data were reviewed in all patients that had been diagnosed with FMS between November 1994 and March 2003. Patients with onset above the of age 18 years, and patients with FMS and concomitant rheumatic diseases were excluded from this study. The study population included two groups: group "A", young children with onset at age 10 years and under and group "B", children with onset above 10 years old. A questionnaire was used at follow-up visits or by telephone interview to evaluate the outcome.
There were 148 children with the diagnosis of FMS (based on ACR criteria), of these 46 children in group A and 102 children in group B. The mean age at onset and mean age at diagnosis were 7.5 years and 10 years in group A, and 13.2 years and 14.5 years in B, respectively. The mean interval between the age of onset and the age at diagnosis was 32 months in group A, and 18 months in group B (p= 0.007). There was a predominance of female gender and Caucasian ethnicity in both groups. Diffuse aching was reported in all patients in both groups. Stiffness, subjective joint swelling, abdominal pain and initial presentation on wheelchair were found more frequently in group A, compared with group B (p= 0.03, 0.001, 0.01, 0.03 respectively). The mean count of tender points at diagnosis was higher in group A, compared with group B (15.3 vs. 14.2, p = 0.004). The differences of other clinical features and laboratory tests in both groups were not statistically significant. Thirty-six patients in group A (78%) and 83 in group B (81%) were available for one or more follow-up visits and/or telephone interview. The mean follow-up period was 14 months in group A, and 19 months in group B (p value = 0.3). There was no difference in the type of treatment or outcome in both groups.
FMS in young children of 10 years old and younger is frequently under-recognized. As compared with the older group, stiffness, subjective joint swelling, abdominal pain, initial presentation on wheelchair and a higher mean count of tender points at diagnosis were significantly more common in the younger age group. However, the type of medications used and outcome were similar in both groups. Prospective studies with large patient population are needed to clarify these findings.