Learning Curve Of Optical Diagnosis With A Resect And Discard Strategy For Screening Colonoscopy: Preliminary Results From The Discard3 Study

Aims Advanced endoscopic imaging allows optical diagnosis of diminutive polyps. Performance thresholds for optical diagnosis have been set to allow a “resect and discard strategy” which may streamline patient care and reduce histopathology need. Aim: to assess early implementation and quality assurance of this strategy in a bowel cancer screening unit setting (1.1 million population).

Methods In this prospective feasibility study, 8 bowel cancer screening colonoscopists completed a validated optical diagnosis training module and performed procedures at St Mark’s Hospital, London (Feb-Oct 2020). All ≤5mm polyps had white-light and narrow-band images. Endoscopists classified the optical diagnosis as high or low confidence. All polyps had standard histopathology.

Performance was analysed in 2 month time periods with active feedback given. There was repeat histology review of inaccurate high confidence optical diagnoses.

Results In the 8 months to date, 639 polyps were optically diagnosed (468 high confidence and 171 low confidence) from 283 patients who were divided into 4 time periods.

The proportion of low confidence diagnoses increased from 15 % in periods 1-2 to 29 % in period 4.

In periods 1-2, 1/8 endoscopists achieved the 90 % accuracy threshold. In periods 3 and 4, 2/8 and 4/8 endoscopists achieved the threshold respectively. Overall, accurate diagnoses increased from 81 % to 86 % (period 1 to 4). Of those who reached the threshold by period 4 the mean number of high confidence calls was 60 (range 41-99).

For periods 1-4, the positive and negative predictive values for optical diagnosis of adenomas were 89.3 % and 64.4 % respectively:

Tab. 1

		Histology		Total
		Adenoma	Non-adenoma
Optical diagnosis	Adenoma	275	57	332
	Non-adenoma	33	103	136
	Total	308	160	468

Conclusions The learning curve for optical diagnosis in a bowel cancer screening setting varies between individual operators. Over time, and with feedback, there is a gradual increase in optical diagnosis accuracy and in the number of colonoscopists achieving the 90 % threshold accuracy target, with a corresponding decrease in the percentage of high confidence calls.

Citation: Ahmad A, Wilson A, Thomas-Gibson S et al. OP184 LEARNING CURVE OF OPTICAL DIAGNOSIS WITH A RESECT AND DISCARD STRATEGY FOR SCREENING COLONOSCOPY: PRELIMINARY RESULTS FROM THE DISCARD3 STUD. Endoscopy 2021; 53: S76.

Publication History

Article published online:
19 March 2021