Table 2.

CTC abnormalities, confirmatory tests and detection of matched abnormalities stratified by size of abnormality shown on CTC

	Largest abnormality suspected at CTC in 2731 gFOBt-positive individuals
	CRC or 10 mm+ polyp	6–9 mm polyp	≤5 mm polyp	Size not recorded	Any suspected polyp/cancer
Number (% of total, (95% CI))	462 (16.9% (14.9% to 18.9%))	176 (6.4% (5.1% to 7.7%))	115 (4.2% (3.2% to 5.2%))	274 (10.0% (7.2% to 13.1%))	1027 (37.6% (33.8% to 41.4%))
Number (% of those with CTC abnormality) undergoing confirmatory test (95% CI)	427 of 462 (92.4% (89.6% to 95.1%))	136 of 176 (77.3% (70.8% to 83.7%))	76 of 115 (66.1% (53.2% to 79.7%))	272 of 274 (99.3% (98.3% to 100%))	911 of 1027 (88.7% (86.2% to 91.4%))
Number (% of total) with matched abnormality (95% CI)	371 (13.6% (11.4% to 15.7%))	99 (3.6% (2.6% to 4.6%))	40 (1.5% 0.9 to 2.0%))	147 (5.4% (3.6% to 7.2%))	657 (24.1% (41.5% to 26.7%))
Histological diagnoses	106 CRC 247 adenomas 18 non-adenomatous polyps	87 adenomas 12 non-adenomatous polyps	22 adenomas 18 non-adenomatous polyps	18 CRC 112 adenomas 17 non-adenomatous polyps	124 CRC 468 adenomas 65 non-adenomatous polyps
Positive predictive value for matched CRC or polyp (95% CI)	86.9% (82.7% to 90.9%)	72.8% (62.8% to 82.7%)	52.6% (43.5% to 61.4%)	54.0% (46.1% to 62.2%)	72.1% (66.6% to 77.6%)
Positive predictive value for matched CRC or adenoma (95% CI)	82.7% (78.6% to 86.5%)	64.0% (52.3% to 74.9%)	28.9% (18.3% to 39.5%)	47.8% (38.8% to 53.6%)	64.9% (59.3% to 70.5%)

CRC, Colorectal cancer; CTC, CT colonography; gFOBt, guaiac faecal occult blood test.