Prevalence and Clinical Use of Anti-Thyroid Antibodies in RA Patients: A Prospective Case-Control Study

Abstract

Aim: To evaluate the prevalence of anti-thyroid antibodies in a cohort of rheumatoid arthritis (RA) patients from south India and their clinical use.

Methods: A cross-sectional epidemiological study was conducted including 1217 patients aged more than 14 years with fever and thrombocytopenia admitted in the medical wards from October 2013 to September 2014. Detailed clinical examination and routine investigations were done; specific investigations like blood culture, widal test, antigen test for malaria, IgM ELISA leptospira, IgM ELISA dengue, bone marrow aspiration/biopsy etc. were done as and when indicated. The data are presented as percentage and numbers. Rates and ratios are computedThe prospective case-control study, conducted for 3 consecutive months in a tertiary care hospital based in India, evaluated 103 RA patients (active group) and 36 age-matched healthy controls without the disease. Both the control and active groups were compared for thyroid autoantibodies, and the clinical evaluation included assessment of swollen joint counts (SJC), tender joint counts (TJC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), pain scale, disease activity score (DAS), rheumatoid factor (RF), anti-nuclear antibody (ANA) and anti-cyclic citrullinated peptide (anti-CCP). The active group subjects were further subdivided into RA patients with and without hypothyroidism, and were compared for normal and abnormal levels of thyroid autoantibodies and the variations were statistically analysed.

Results: The corresponding mean age of the subjects belonging to the active and control groups were 47.09±11.29 and 41.03±11, with a female to male ratio of 1:0.12 and 1:0.29 respectively. Among the various thyroid autoantibodies compared between the active and control groups, a significant correlation (P=0.00936) was observed for anti-TTG antibodies. Also, the study has noted a significantly elevated level of anti-TPO antibodies in RA patients with hypothyroidism compared to the group without hypothyroidism (P=0.0074).

Conclusion: A significantly increased level of anti-TPO antibodies was noted in RA patients with hypothyroidism.