Table 2.

Health outcomes, costs, incremental cost-effectiveness ratios of adenoma surveillance strategies for 50-year-olds with adenomas detected at screening colonoscopy or FIT ^*

		Outcomes per 1000 adults
Risk group †	Strategy by mode of polyp detection ‡	CRC cases	CRC deaths	QALYs § (disc.)	QALY‖ gained (disc.)	Colonoscopies	Cost (thousand $; disc.) ¶			ΔCost/ΔQALY (disc.) **
							Colonoscopy	Treatment	Total
LRA	Colonoscopy-detected
	No surveillance/No return to screening	109	44	19,456	-	0	0	4,110	4,110	Dom.
	Return to routine screening	65	19	19,570	114	1,736	1,199	2,671	3,870	Ref.
	Low-intensity surveillance	59	16	19,577	121	2,013	1,341	2,557	3,898	4,000
	High-intensity surveillance	49	12	19,598	142	3,178	2,178	2,112	4,290	18,400
	FIT-detected
	No surveillance/No return to screening	119	48	19,407	-	0	0	4,699	4,699	Dom.
	Return to routine screening	92	25	19,510	103	551	542	3,994	4,536	Dom.
	Low-intensity surveillance	74	20	19,530	123	1,591	1,144	3,310	4,454	Ref.
	High-intensity surveillance	55	14	19,565	158	3,207	2,211	2,630	4,841	11,100
HRA	Colonoscopy-detected
	No surveillance/No return to screening	172	70	19,303	-	0	0	6,622	6,622	Dom.
	Return to routine screening	105	31	19,491	188	1,720	1,231	4,402	5,633	Ref.
	Low-intensity surveillance	89	23	19,525	222	2,712	1,960	3,824	5,784	4,500
	High-intensity surveillance	75	18	19,557	254	3,898	2,886	3,166	6,052	8,400
	FIT-detected
	No surveillance/No return to screening	169	69	19,302	-	0	0	6,608	6,608	Dom.
	Return to routine screening	131	34	19,462	159	600	581	5,532	6,113	Dom.
	Low-intensity surveillance	88	23	19,520	218	2,709	1,955	3,901	5,856	Ref.
	High-intensity surveillance	75	18	19,553	251	3,883	2,872	3,258	6,131	8,400

Abbreviations: CRC = colorectal cancer; disc. = discounted; Dom. = dominated (less effective and more costly); FIT = fecal immunochemical test; HRA = high-risk adenoma; ICER = incremental cost-effectiveness ratio; LRA = low-risk adenoma; QALY = quality-adjusted life-year; Ref. = reference scenario.

^*Adenomas were detected through colonoscopy screening or at colonoscopy after FIT screening.

^†LRAs were defined as 1–2 tubular adenomas <10 mm in diameter; HRAs were defined as ≥3 or more tubular adenomas <10mm in diameter, and/or ≥1 advanced adenoma (tubular adenoma ≥10 mm in diameter, tubulovillous adenoma, or adenoma with high-grade dysplasia). In the model histology was not described, and an advanced adenoma was considered a large adenoma.

^‡There were four scenarios evaluated: No surveillance/No return to routine screening consisted of a baseline examination only; Return to routine screening consisted of continued colonoscopy screening after 10 years through age 70 years for colonoscopy-detected patients, and return to FIT screening through age 75 years for FIT-detected patients; Low-intensity surveillance consisted of a colonoscopy after 5 years in case of HRA detection, and colonoscopy after 10 years after detection of LRA, and 10 years or return to screening in case of no detected adenoma (Supplementary Table 1), with a stopping age of 80 years; High-intensity surveillance consisted of a colonoscopy after 3 years in case of an HRA, colonoscopy after 5 years in case of an LRA; and colonoscopy after 10 years in case of no detected adenoma in surveillance (Supplementary Table 1), with a similar stopping age of 80 years.

^§QALYs were discounted by 3% per annum to baseline at age 50, 60, or 70 years, respectively. See Supplementary Table 7 for a specification of quality of life adjustments.

^‖QALY gained are presented compared to No surveillance/No return to screening.

^¶Costs were discounted by 3% per annum to baseline at age 50, 60, or 70 years, respectively. Cost of colonoscopy complications were included. See Supplementary Table 7 for a specification of cost components.

^**Additional cost per QALY gained for some surveillance strategy compared to the next less effective, non-dominated strategy.