Clinical Impact of HLA-B27 on Juvenile Idiopathic Arthritis: Eighteen Years of Follow-up in the Population-Based Nordic Juvenile Idiopathic Arthritis Cohort.

Objective: We have previously shown that HLA-B27 was negatively associated with remission status eight years after the onset of juvenile idiopathic arthritis (JIA). We now aimed to study the associations of HLA-B27 with clinical features and disease outcomes 18 years after the onset of JIA.

Methods: We studied 434 patients from the population-based Nordic JIA cohort. Demographic and clinical data, including remission status, were collected consecutively at baseline, eight years after disease onset, and 18 years after disease onset and presented in relation to HLA-B27 status.

Results: The HLA-B27 status was available for 416 of the 434 participants (96%) and was positive for 93 participants (22.4%), more often in men (P = 0.01). The sacroiliac, hips, and subtalar joints were more frequently involved in individuals who were HLA-B27 positive than in individuals who were HLA-B27 negative. In almost half of the individuals with HLA-B27 positivity and uveitis, the uveitis was asymptomatic. Uveitis, inflammatory back pain, sacroiliitis, arthritis in hip, tarsal, and subtalar joints, and enthesitis during the disease course were all associated with a lower rate of remission off medication. HLA-B27 positivity was significantly associated with a higher risk of not being in remission off medication after 18 years (odds ratio [OR] 2.6), especially in men (OR 5.6).

Conclusion: Clinical features related to spondylarthropathies were more common in patients who were HLA-B27 positive and associated with worse outcomes and nonremission 18 years after disease onset, particularly in men. Our results underline the adverse impact of having HLA-B27 positivity on long-term outcomes in individuals with JIA.