Objective: To compare the clinical, functional, and radiographic outcomes in patients with enthesitis-related arthritis (ERA) with those in patients with other subtypes of juvenile idiopathic arthritis (JIA) and healthy controls, and to determine genetic markers, patient characteristics, and early disease variables that predict the development of remission, sacroiliitis, and physical limitations in ERA.
Methods: Fifty-five children with ERA who were first admitted to Rikshospitalet Medical Center between 1980 and 1985 were studied. Patients with oligoarthritis or polyarthritis who were admitted during the same period (n = 55) and individuals from a national population registry (n = 55) were matched for sex and age and used as controls. Health status was assessed after a median of 15.3 years of disease (range 11.7-21.9 years) and, in some patients, was reassessed after a median of 23.0 years (range 19.7-29.4 years) of disease, by use of the 36-item Short Form health survey and the Health Assessment Questionnaire. Clinical and radiographic examinations were performed at the 15-year followup visit. Variables relating to the onset of disease were retrospectively obtained by chart review. HLA alleles were determined by genotyping and serologic testing.
Results: Patients with ERA had lower levels of physical functioning, poorer physical health, and more bodily pain compared with patients with oligoarthritis or polyarthritis (after a median of 15.3 and a median of 23.0 years) and normal controls (after a median of 15.3 years). Among patients with ERA, remission occurred in 44%, sacroiliitis was observed in 35%, and reduced spinal flexion was observed in 75%. Predictors of failure to attain disease remission included the following: ankylosing spondylitis (AS) in a first-degree relative, the presence of HLA-DRB1*08, and ankle arthritis within the first 6 months. HLA-DPB1*02 was a protective factor, whereas a persistently elevated erythrocyte sedimentation rate (ESR), and hip arthritis within the first 6 months were risk factors for sacroiliitis. Female sex, a family history of AS, and high numbers of affected joints within the first 6 months predicted poor physical health status after 23 years. Male sex was associated with reduced anterior flexion of the spine.
Conclusion: In this study, patients with ERA had poorer physical outcomes compared with patients with oligoarticular or polyarticular JIA and controls from the general population. A family history of related diseases, sex, the presence of HLA-DRB1*08, the absence of HLA-DPB1*02, a persistently elevated ESR, early hip or ankle arthritis, and high numbers of affected joints were predictors of an unfavorable outcome.