Low frequency of axial involvement in Caucasian pediatric patients with seronegative enthesopathy and arthropathy syndrome after 5 years of disease.

In order to establish how many children with seronegative spondyloarthropathy (SpA) starting with peripheral arthritis and/or enthesitis will develop ankylosing spondylitis (AS), 13 consecutive Caucasian pediatric patients, (11 with the seronegative enthesopathy and arthropathy (SEA) syndrome and 2 with isolated B27 associated peripheral arthritis or enthesitis at entry), were followed prospectively with no loss for more than 5 years. Sacroiliac joint plain films obtained at the last visit were mixed with those of 14 control subjects and read blindly. The course of SpA was self-limiting in 6 patients and recurrent in the other 7. Six patients had episodes of inflammatory cervical and/or lumbar pain during followup. However, none showed any limitation of spinal movement in the asymptomatic periods. Only one patient (9.1%) of 11 with the SEA syndrome showed bilateral sacroiliitis and met New York criteria for AS after 5 years of disease. Our results suggest that the proportion of Caucasian children with the SEA syndrome developing AS is much lower than the 75% found in a similar study on Mexican children. Lack of evaluation of all patients after 5 years, the reading of pelvic plain films without reducing observer error, and the male predominance in the Mexican study, probably in addition to ethnic or environmental factors, may account for differences.