Validation of the Collaborative Ocular Tuberculosis Study (COTS) Calculator for the Diagnosis of Ocular Tuberculosis...

To evaluate the diagnostic accuracy of the Collaborative Ocular Tuberculosis Study (COTS) calculator in predicting ocular tuberculosis (OTB) and compare its performance with ophthalmologists' clinical judgment among Thai patients.

This retrospective study included patients with suspected OTB. Demographic, clinical, laboratory, and imaging data were scored using the COTS calculator (scores 1-5). Clinician judgment combined with treatment success served as the reference standard. Diagnostic accuracy was assessed at two thresholds: COTS ≥ 4 and COTS = 5. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and area under the ROC curve (AUC) were calculated.

Sixty-two patients were included (42.8 ± 16.5 years). OTB was diagnosed in 45 (72.6%). The COTS calculator demonstrated moderate overall diagnostic accuracy, with AUC of 0.675 (95%CI:0.544-0.788,p = 0.0304). COTS = 5 showed the highest specificity (76.5%;95%CI,52.7-90.4) but low sensitivity (35.6%;95%CI,23.2-50.2). Clinician judgment had the highest sensitivity (100.0%;95%CI,92.1-100.0) with low specificity(29.4%;95%CI,13.3-53.1%). COTS ≥ 4 provided the best balance (sensitivity 68.9%;95%CI,54.3-80.5, specificity 70.6%,95%CI,46.9-86.7), with PPV/NPV of 86.1%/46.2% (vs. 80.0%/31.0% for COTS = 5). Clinician judgment showed the highest screening performance (PPV 78.9%,NPV 100.0%). The overall accuracy for all locations, using COTS ≥ 4, was 69.35%, while the specific accuracies for choroiditis, panuveitis, and retinal vasculitis were 80.00%, 73.08%, and 63.16% respectively.

The COTS calculator demonstrates a balanced diagnostic performance within this cohort at a cutoff score of $\ge 4$, making it a valuable clinical adjunct. While ophthalmologists' clinical judgment provided superior sensitivity and overall accuracy. These findings support the COTS calculator as a useful adjunct, showing high accuracy specifically for choroiditis and panuveitis in diagnosing OTB.