A clinicopathogenetic study on graves’ orbitopathy in a tertiary care hospital setting in eastern india

Background: The prevalence of Graves’ Orbitopathy(GO) in Indian population is reported to be less, as compared to Caucasians, but there are few and inconclusive data. The role of TRAb in GO development and prediction of activity or severity of GO is not yet clearly understood. 
Objective: To evaluate the prevalence and clinico-radiological profile of GO in an Indian cohort and to find out the correlation of TRAb and extra ocular muscle (EOM) thickness with activity and severity of GO.
Methods: Out of 150 patients with GD, 45 treatment naïve patients- 23 with GO and 22 with Graves’ disease(GD) without GO were evaluated clinico-radiologically.
Results: 32% had clinical based GO (Mild GO 73%, moderate 26%, sight-threatening 1%). Mean TRAb was slightly higher in GO (24.7133 ± 14.8627IU/l) in comparison to GD (19.8775 ± 10.8022 IU/l, p=0.2469).The presence of GO was significantly associated with smoking [OR: 1.85; 95% CI (-.79 – (-.10), p=0.013] and TRAb positivity [OR: 2.15; 95% CI (.57 – 2.30), p=0.002]. TRAb titers were significantly higher in males and smokers and significantly associated with the degree of proptosis of both eyes. There was no association of TRAb with CAS or degree of severity in GO.GO had increase thickness of recti muscles, determined from MRI, versus GD. The cut-offs for thickness in GO vs GD patients are lower compared to Caucasian data. The values of recti thickness had significant correlation with activity scores (p<0.0001). TRAb correlated with the maximum rectus thickness determined by MRI.
Conclusion: TRAb is an important but not the sole pathogenetic factor in GO. Imaging derived rectus muscle thickness, analyzed with respect to regional normative data is associated with the activity of GO, the maximum rectus muscle thickness being an important parameter.