Thyroid-joint crosstalk: a systematic review and meta-analysis of thyroid autoimmunity and dysfunction in juvenile idiopathic arthritis

BACKGROUND: Recent observational studies outlined the concomitant presence of autoimmune diseases in children with juvenile idiopathic arthritis (JIA), including endocrine autoimmunity. Despite the growing evidence of thyroid involvement in JIA, available data are heterogeneous and fragmented. We aimed to systematically review the available evidence on the prevalence of thyroid autoantibody positivity and thyroid dysfunction in patients with JIA. METHODS: PubMed/Medline, Cochrane, and Scopus databases were approached to identify studies reporting data on thyroid autoantibody positivity and dysfunction in children with JIA. RESULTS: A total of 15 studies were included in the final analysis, encompassing 19 015 children with JIA (13 225 females, 69.6%) with a weighted mean age of 8.0 years (range 1.8-21 years). The pooled prevalence estimates of antithyroid antibody positivity and thyroid dysfunction were 0.04 (95% CI: 0.03-0.05) and 0.04 (95% CI: 0.03-0.08), respectively. The risk difference for thyroid autoantibody positivity between children with JIA and controls was 0.08 (95% CI: 0.02-0.14). Possible risk factors were analyzed: the presence of family history for thyroid autoimmune disease (odds ratio - OR 3.91, 95% CI 1.86-8.25), concurrent Antinuclear Antibodies (ANA) positivity (OR 1.62, 95% CI 1.13-2.31), and older age (MD 2.10 years, 95% CI 1.32-2.89) were associated with thyroid autoantibody positivity and/or thyroid dysfunction in children with JIA. No significant difference emerged for the specific JIA form. CONCLUSION: Thyroid dysfunction may be detected in children with JIA, with a significant risk difference in comparison to healthy controls. Specific clinical characteristics, such as family history, ANA positivity, and older age at JIA onset, may suggest which patients should benefit from thyroid autoantibody screening.