FRI0535 NEWLY DETECTED HYPERTHYROIDISM WITH THERAPEUTIC INDICATIONS IN RHEUMATIC DISEASE PATIENTS AND HEALTHY CONTROLS IN JAPAN: A RETROSPECTIVE COHORT STUDY
Authors: S. Fukui, Y. Ikeda, G. Kidoguchi, T. Nakai, H. Ozawa, S. Kawaai, A. Koido, Y. Ohara, H. Shimizu, H. Tamaki, K. Yamaguchi, M. Okada
Journal: Annals of the Rheumatic Diseases (2020)

Background: Thyroid disorders are known as common comorbidities of rheumatic diseases(RD) [1]. However, data regarding prevalence of hyperthyroidism with treatment indication in RD patients are limited. Objectives: This study aims to reveal and compare the frequency of newly developed hyperthyroidism with treatment indication between RD patients and healthy controls (HC), and identify risk factors to identify patients whose thyroid function should be followed up carefully. Methods: We retrospectively reviewed charts of RD patients and HC who had thyroid stimulating hormone (TSH) measured at least once between 2004 and 2018 from immuno-rheumatology center and preventive medicine center in St. Luke’s International Hospital, Japan. We compared frequency of hyperthyroidism requiring treatment (TSH ≦ 0.1μU/mL or for which physicians started treatment) with Kaplan-Meier curve and log rank test. Cox regression multivariate analysis was performed to reveal risk factors for the new onset of hyperthyroidism with treatment indication in participants without treatment-indicated hyperthyroidism at initial assessments. Results: Overall, 2307 RD patients and 78251 HC were included. Newly detected hyperthyroidism with treatment indication were significantly more frequent in RD patients at initial assessment (1.3% vs 0.5 %, p &lt; 0.001) and in total (2.9% vs 1.7%, p&lt;0.001) (Table 1, Figure 1). Cox regression multivariate analysis revealed systemic lupus erythematosis (SLE), polymyositis dermatomyositis (PMDM), mixed connective tissue disease (MCTD) as significant risk factors of new developments of hyperthyroidism during follow up after adjusting confounders. (Table 2) Table 1. Patients characteristics and results of hyperthyroidism Rheumatic Disease (n = 2307 ) Control (n = 78251 ) p.value Age(yr) 53.7 (16.2) 46.1 (11.9) &lt;0.001 Female (%) 1826 (79.2) 38632 (49.4) &lt;0.001 Rheumatoid arthritis (%) 1091 (47.3) - NA Spondyloarthritis 161 (7.0) - NA ANA associated disease (%) 944 (40.9) - NA SLE(%) 363 (15.7) - NA SS (%) 396 (17.2) - NA PMDM(%) 104 (4.5) - NA SSc (%) 222 (9.6) - NA MCTD (%) 43 (1.9) - NA Vasculitis (%) 202 (8.8) - NA Others (%) 244 (10.6) - NA Times of TSH measurement 2.0 [1.0, 5.0] 5.0 [3.0, 9.0] &lt;0.001 Follow up of TSH (days) 258.00 [0, 1315] 1992 [958, 3632] &lt;0.001 Baseline TSH (μU/mL) 2.28 (3.21) 2.15 (4.07) 0.137 ≦0.45 μU/mL (%) 86 (3.7) 1371 (1.8) &lt;0.001 ≦0.1 μU/mL (%) 29 (1.3) 389 (0.5) &lt;0.001 Baseline FreeT4 (μU/mL) 1.16 (0.24) 1.30 (0.20) &lt;0.001 ≧1.65 μU/mL (%) 17 (0.8) 2355 (3.0) &lt;0.001 TSH level in follow up ≦0.45 μU/mL (%) 231 (0.0) 3926 (5.0) &lt;0.001 ≦0.1 μU/mL (%) 84 (3.6) 1388 (1.8) &lt;0.001 Newly detected hyperthyroidism with treatment indication (%) 68 (2.9) 1350 (1.7) &lt;0.001 At initial assessment (%) 29 (1.3) 389 (0.5) &lt;0.001 In follow up (%) 39 (1.6) 961 (1.2) &lt;0.001 Treatment for hyperthyroidism (%) 21 (0.9) 325 (0.4) 0.002 Figure 1. Hyperthyroidism with treatment indication in rheumatic patients and control Table 2. Risk factors for newly detected hyperthyroidism with treatment indication Adjusted HR p value Age 0.99 (0.98-0.99) &lt; 0.001 Female 2.68 (2.31-3.12) &lt; 0.001 BMI 1.04 (1.02-1.06) &lt; 0.001 Baseline TSH ≦ 0.45 5.71 (4.47-7.30) &lt; 0.001 Baseline Free T4 ≧ 1.65 1.16 (0.79-1.69) 0.45 Rheumatoid arthritis 1.05 (0.50-2.21) 0.90 ANA associated diseases - - SLE 2.29 (1.11-4.71) 0.025 SS 1.91 (0.91-4.01) 0.089 PMDM 12.90 (5.50-30.22) &lt; 0.001 SSc 0.67 (0.18-2.43) 0.541 MCTD 8.02 (2.62-24.51) &lt; 0.001 Vasculitis 1.44 (0.35-5.92) 0.610 Spondyloarthritis 3.04 (0.74-12.52) 0.120 Others 1.98 (0.67-5.81) 0.214 Conclusion: Hyperthyroidism with therapeutic indications are considerably more frequent in RD patients (particularly with SLE, PMDM and MCTD) both at initial assessment and during follow up. We recommend routine screening at initial assessment and careful follow up of thyroid function test in those patients. References: [1] Rev Bras Rheumatol 2012;52(3):417-430 Disclosure of Interests: None declared