ADEQUACY OF SIGMOIDOSCOPY IN COMPARISION TO COLONOSCOPY TO ASSESS DISEASE ACTIVITY DURING FOLLOW UP IN PATIENTS WITH ULCERATIVE COLITIS

BACKGROUND Endoscopic remission is the current treatment target in patients with Ulcerative Colitis (UC). Literature on adequacy of sigmoidoscopy in comparison to colonoscopy to assess endoscopic and histologic activity during follow up is sparse. METHODS This is an interim analysis of a prospective study of patients diagnosed with UC with disease extent proximal to the sigmoid colon. Fifty adult patients underwent a complete colonoscopy with segmental biopsies. Endoscopic disease activity was graded using Mayo Endoscopic Subscore (MES) and the Ulcerative Colitis Endoscopic Index of Severity score (UCEIS). The histological grading was done using the Nancy score, Robarts Histopathology Index (RHI) and Simplified Geboes Score (SGS). The maximum rectosigmoid disease activity was compared with the maximum disease activity in the rest of the colon. RESULTS Endoscopic Correlation: Sigmoidoscopic evaluation using MES showed good correlation with pan colonoscopic evaluation for disease activity with a sensitivity of 92.11%, specificity of 66.67%, accuracy of 86% (95% CI – 73.26% to 94.18%), kappa value (k) of 0.58 (p value < 0.001) and Area under curve (AUC) of 0.82 (95% CI- 0.74 to 0.942). Similarly, sigmoidoscopic evaluation using UCEIS score showed good correlation with pan colonoscopic evaluation for disease activity with a sensitivity of 95.0%, specificity of 70%, accuracy of 90% (95% CI – 78.19% to 96.67%), k of 0.68 (p value < 0.001) and AUC of 0.895 (95% CI- 0.805 to 0.924). Disease activity in the colon missed by performing a sigmoidoscopy using MES and UCEIS score is only 6% and 4% respectively. Histological Correlation: Histologic findings in rectosigmoid showed good correlation with histologic findings in rest of the colon using Nancy’s score [Sensitivity of 97.96%, specificity of 100%, accuracy of 98% (95% CI – 89.35% to 99.95%), k of 0.658 (p value < 0.001) and AUC of 0.99 (95% CI- 0.959 to 1.0)], Simplified Geboes Score [Sensitivity of 97.92%, specificity of 100%, accuracy of 98% (95% CI – 89.35% to 99.95%), k of 0.79 (p value < 0.001) and AUC of 0.99 (95% CI- 0.962 to 1.0)], and Robarts Histopathology Index [Sensitivity of 95.56%, specificity of 80%, accuracy of 94% (95% CI – 83.45% to 98.75%), k of 0.694 (p value < 0.001) and AUC of 0.878 (95% CI- 0.667 to 1.0) ]. Histologic disease activity in the colon missed by performing a sigmoidoscopy using Nancy score, SGS and RHI is only 2%, 2% and 4% respectively. CONCLUSION In patients diagnosed with UC and having disease extent proximal to the sigmoid colon, sigmoidoscopic evaluation has good correlation with pan colonoscopic evaluation for grading endoscopic and histological disease activity. A sigmoidoscopic examination is adequate to assess the disease activity in patients with disease extent proximal to the sigmoid colon.