Correlations between Clinical Activity Score and Serological and Radiological Data in Treatment-naïve Ethnic Han Chinese Thyroid Eye Disease

PURPOSE: Clinical activity score (CAS) is widely used to assess thyroid eye disease (TED) activity, but its predictive value in East Asian patients remains unclear. This study evaluated correlation between CAS and both radiological and serological markers in treatment-naïve ethnic Han Chinese TED patients. METHODS: Cross-sectional study of treatment-naïve ethnic Han Chinese TED patients managed at The Chinese University of Hong Kong between January 2014 and May 2022. STIR signal intensity was quantified using signal intensity ratio (SIR), while disease activity was assessed clinically using CAS. RESULTS: A total of 188 patients with a mean onset age of 50±14 years who underwent baseline MRI were included. The mean presenting CAS was 1.4±1.3. A weak positive correlation was observed between CAS and the SIR of the levator palpebral superioris/superior rectus complex (r=0.196, P=0.00709). Nominal positive correlations were observed between CAS and the SIRs of the inferior rectus (r=0.185, P=0.0112), and medial rectus (r=0.167, P=0.0224). In subgroup analysis of patients presenting with CAS ≥3, nominal positive correlations were observed between CAS and the SIRs of the lateral rectus (r=0.374, P=0.0416), medial rectus (r=0.351, P=0.0487), and inferior rectus (r=0.335, P=0.0348). No correlation was identified in patient with CAS <3. No significant correlation was found between CAS and serological markers. CONCLUSIONS: The correlation between CAS and STIR signals was generally weak, and no significant correlation was identified between CAS and serological markers. These findings suggest that orbital MRI may provide complementary information beyond clinical assessment in evaluating disease activity in Ethnic Chinese TED patients.