Risk factors associated with missed colorectal flat adenoma: A multicenter retrospective tandem colonoscopy study

Table 3 “Per-adenoma” miss rates and the risk factors in detection of flat adenomas during colonoscopy n (%)

Risk factor	Total(n = 916)	Diagnosed(n = 510)	Missed(n = 406)	Univariate analysis		Multivariate analysis
				χ2test	P value	OR (95%CI)	P value
Patient-related
Age				9.021	0.003
< 60 (yr)	493	297 (60.2)	196 (39.8)			1
≥ 60 (yr)	423	213 (50.4)	210 (49.6)			2.062 (1.390-3.061)	< 0.001
Sex				1.586	0.208
Male	559	302 (54.0)	257 (46.0)
Female	357	208 (58.3)	149 (41.7)
Anesthesia				0.197	0.657
Yes	239	136 (56.9)	103 (43.1)
No	677	374 (55.2)	303 (44.8)
History of adenomas
Yes	243	129 (53.1)	114 (46.9)	0.899	0.343
No	673	381 (56.6)	292 (43.4)
Previous surgery				0.105	0.746
Yes	45	24 (53.3)	21 (46.7)
No	871	486 (55.8)	385 (44.2)
Diverticulosis				0.013	0.909
Yes	51	28 (54.9)	23 (45.1)
No	865	482 (55.7)	383 (44.3)
Numbers at first colonoscopy				0.163	0.686
< 3	580	320 (55.2)	260 (44.8)
≥ 3	336	190 (56.5)	146 (43.5)
Concomitance with protruding adenoma(s) at first colonoscopy				127.154	< 0.001
No	280	234 (83.6)	46 (16.4)			1
Yes	636	276 (43.4)	360 (56.6)			7.759 (4.420-13.618)	< 0.001
Bowel preparation				45.773	< 0.001
Good	757	460 (60.8)	297 (39.2)			1
Poor	159	50 (31.4)	109 (68.6)			4.389 (2.314-8.352)	< 0.001
Adenoma-related
Size				122.706	< 0.001
≥ 10 mm	172	159 (92.4)	13 (7.6)			1
6-9 mm	391	202 (51.7)	189 (48.3)			9.239 (4.306-19.824)	< 0.001
< 6 mm	353	149 (42.2)	204 (57.8)			19.613 (8.984-42.822)	< 0.001
Location				74.571	< 0.001
Rectum	184	152 (82.6)	32 (17.4)	6.81	0.0091	1
Left colon	322	175 (54.3)	147 (45.7)			2.866 (1.623-5.062)	< 0.001
Right colon	410	183 (44.6)	227 (55.4)			3.259 (1.819-5.838)	< 0.001
Advanced adenoma				113.850	< 0.001
Yes	205	181 (88.3)	24 (11.7)
No	711	329 (46.3)	382 (53.7)
Pathologic classification				74.745	< 0.001
Tubular	745	366 (49.1)	379 (50.9)
Tubulovillous and villous	151	132 (87.4)	19 (12.6)
Serrated	20	12 (60.0)	8 (40.0)
Procedure-related
Proficiency				28.18	< 0.001
> 1000 cases	585	363 (62.1)	222 (37.9)			1
500-1000 cases	234	109 (46.6)	125 (53.4)			2.219 (1.397-3.525)	0.001
< 500 cases	97	38 (39.2)	59 (60.8)			3.003 (1.568-5.754)	0.001
Specialty				6.86	0.009
Gastroenterologist	739	427 (57.8)	312 (42.2)
Non-gastroenterologist	177	83 (46.9)	94 (53.1)
Operative mode				4.862	0.027
One-person technique	721	415 (57.6)	306 (42.4)
Two-person technique	195	95 (48.7)	100 (51.3)
Withdrawal time				6.069	0.014
≥ 6 min	254	158 (62.2)	96 (37.8)			1
< 6 min	662	352 (53.2)	310 (46.8)			1.958 (1.276-3.006)	0.020

¹The comparison between the left and right colon.