Relationship Between Serum Thyroid Autoantibody Titers and Disease Severity in Rheumatoid Arthritis Patients in Gonabad in 2022-2023

Abstract

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation, pain, and impaired daily function. Rheumatoid arthritis can affect multiple systems, including the thyroid. Thyroid dysfunction may be a factor in the exacerbation of RA symptoms or the complication of treatment. The aim of this study was to investigate the relationship between thyroid autoantibody titers and disease severity in patients with RA who were referred to the Allameh Bohlool Hospital in Gonabad. In this matched case-control study, patients were recruited during a 4-month period. A total of 182 participants were enrolled, including 91 patients with RA and 91 age- and sex-matched controls. Thyroid function tests (TSH, T 3 , T 4 ) and autoantibody titers (TRAb, anti-TPO, anti-TG) were measured by enzyme-linked immunosorbent assay. Disease activity was assessed by the Disease Activity Score based on 28 joints and C-reactive protein (DAS28-CRP) questionnaire. Data were analyzed using SPSS version 27.0 Statistical significance was set at P  < .05. Patients with RA demonstrated higher rates of thyroid dysfunction and autoantibody positivity compared with controls. In particular, more than 25.3% of patients with RA had hypothyroidism. This was significantly higher than in controls (12.1%). The severity of the disease, as assessed by DAS28-CRP, categorized the patients into remission (25.3%), low (28.6%), moderate (41.8%), and high (4.4%) activity groups. Elevated levels of TRAb, anti-TPO, and anti-TG were observed in 22%, 22%, and 19.8% of patients with RA, respectively. This compares to 9.9%, 15.4%, and 13.2% in controls. Elevated T 3 levels ( P  = .002) and TRAb positivity ( P  = .028) were significantly more frequent in patients with RA than in controls. Multiple logistic regression demonstrated that TSH (odds ratio [OR] = 3.498, CI = 1.279-9.570, P  = .015), T3 (OR = 4.057, CI = 1.526-10.789, P  = .005), and T 4 (OR = 0.105, CI = 0.019-0.572, P  = .009) were significantly associated with RA. Our findings suggest that thyroid dysfunction and thyroid autoantibodies are relatively common among patients with RA. These findings support consideration of thyroid function assessment in appropriate clinical settings, although larger prospective studies are warranted to confirm these observations.