58% Barrett’s Index Predicts Sight-Threatening Optic Neuropathy in Graves’ Orbitopathy, Suggests Study

While GO is the most common extra-thyroidal feature of Graves’ disease, existing radiological markers were established in Caucasian populations, creating a clinical gap due to the anatomically shallower orbits of Indian patients. Therefore, Dr. Felix K. Jebasingh and his team from the Department of Endocrinology, Diabetes and Metabolism at Christian Medical College, Vellore, India, evaluated active GO patients to determine the prognostic value of BI and the Nugent index (NI) for predicting DON and treatment outcomes.

Therefore, the 16-year retrospective study at an Indian tertiary center evaluated 58 orbits from 29 patients with active Graves’ orbitopathy (Clinical Activity Score ≥3) to assess the diagnostic accuracy of Barrett's and Nugent indices using magnetic resonance imaging and computed tomography. The analysis excluded patients with mild or inactive disease, prior steroid use, or missing records.

Key Clinical Findings of the Study Includes:

• Barrett's Index Thresholds: Investigators found a BI cut-off of 58% optimal for predicting DON (area under the curve (AUC): 0.705, sensitivity: 60%, specificity: 68.8%) and sight-threatening disease (AUC: 0.811, sensitivity: 70%, specificity: 81.6%).

• BI-Associated Outcomes: The study linked a higher BI with DON (61.4% vs 51.1%, P = 0.03), lower steroid response (63.7% vs 54.2%, P = 0.043), and increased surgical needs (62.85% vs 49.3%, P = 0.001).

• Nugent Index Associations: Researchers linked an NI of 1 or greater with sight-threatening disease (48.2% vs 22.2%, P = 0.02) and higher steroid requirements (54.8% vs 23.8%, P = 0.04).

• Antibody Correlation: The authors noted that thyrotropin receptor antibody (TRAb) levels exceeding twice the upper normal limit (ULN) are associated with sight-threatening GO (50% vs 14%, P = 0.026) and higher BI (57.7% vs 44.8%, P = 0.002).

• Ocular Presentation Severity: The paper highlighted that sight-threatening GO occurred in 34.5% of cases, correlating with higher BI (62.8% vs 47.6%, P < 0.001) and older age (49.9 ± 16 years vs 42.9 ± 10.9 years, P = 0.053).

The results suggest that a BI of 58% serves as an effective diagnostic threshold for DON in Indian patients, achieving 60% sensitivity and 68.8% specificity. However, the authors emphasize that while these radiological parameters are valuable, clinical assessment remains the cornerstone for diagnosing sight-threatening complications.

Thus, the study concludes that clinicians can consider utilizing this population-specific BI threshold as a complementary tool for the early diagnostic sub-categorization and objective characterization of patients with active GO who may be at risk of developing DON.

Although the study is limited by its retrospective design, small sample size, and lack of a concurrent control group, further prospective trials in larger cohorts could help validate these radiological thresholds and examine the confounding impacts of age, gender, and comorbidities on these indices.

Reference

Agarwal K, Joy AA, Veerappan M, Rallapalli SS, Peter J, Sahu S, et al. Dysthyroid optic neuropathy in Graves’ orbitopathy: Insights from a single centre and limitations of the radiological indices. Indian J Endocr Metab 2026;30:251-7.