Roel Bogie

Optical diagnosis of diminutive polyps in the Dutch bowel cancer screening program: Are we ready to start?

Table 8.3: Optical diagnosis versus histological evaluation of diminutive polyps.*

Lesions in colon and rectum (n=3028) Adenomas (n=2038)** Hyperplastic polyps (n=563)**

Overall accuracy (95% CI)

76% (74-77) 90% (88-91) 47% (44-50) 78% (76-79) 69% (66-73)

79% (77-80) 48% (44-53) 85% (84-87) 43% (39-47)

Sensitivity (95% CI) Specificity (95% CI)

Positive Predictive Value (95% CI) Negative Predictive Value (95% CI)

88% (86-89) Lesions in the rectosigmoid (n=1222) Adenomas (n=602)**

Hyperplastic polyps (n=439)**

Overall accuracy (95% CI)

72% (69-74) 89% (86-92) 55% (51-59) 66% (62-69) 84% (80-87)

71% (69-74) 54% (49-59) 81% (78-84) 61% (56-66) 76% (73-78)

Sensitivity (95% CI) Specificity (95% CI)

Positive Predictive Value (95% CI) Negative Predictive Value (95% CI)

*Diagnostic performance for different polyp subtypes (hyperplastic and adenomatous lesions) were calculated by dichotomizing outcomes, where histological outcome is used as reference. **These numbers represent the total number of adenomas and hyperplastic polyps using histological evaluation, i.e. the reference.

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Performance of optical diagnosis Optical diagnosis for diminutive adenomas in the colon and rectum showed a diagnostic accuracy of 76% (95% CI: 74 – 77) compared to histological diagnosis. The NPV for adenomatous histology was 69% (95%CI: 66 – 73, Table 8.3 ). In the rectosigmoid, a total of 1222 diminutive lesions were found and the NPV for adenomatous histology was 84% (95% CI: 80 – 87). For hyperplastic polyps in the rectosigmoid the NPV was 76% (95% CI: 73 – 78), the PPV was 61% (95% CI: 56 – 66) and the overall accuracy was 71% (95% CI: 69 – 74, Table 8.3 ). A total of 150 polyps in the rectosigmoid (12.3% of the total) were optically misdiagnosed as hyperplastic. In 5.1% and 1.9% of the cases, an adenoma or sessile serrated lesion, respectively, would have been left in place (5.3% other/no abnormality, Table 8.4 ). For optically misdiagnosed lesions (in 139 of 150 cases photo documentation available), no significant difference was found with regard to use of IEE ( P =0.620). Diagnostic accuracy for diminutive adenomas in the colon and rectum ranged from 74 to 78% ( P =0.393) between the four endoscopy units and regarding hyperplastic lesions in the rectosigmoid, diagnostic accuracy ranged from 70 to 73% ( P =0.769, Table 8.2 ). Overall diagnostic accuracy between the 15 endoscopists ranged from 69 to 87%. From 2576 polyps photo documentation was available. Image enhancement had been documented by endoscopy photos in 36.9%, where in the majority of the cases I-scan was used. There was no significant difference between the use of IEE and the correct optical diagnosis for both adenomas

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