Table 1. Baseline Characteristics of the Study Patients.

	All patients	High-risk → no or low-risk	High-risk → high-risk	p value
Number (%)	434	383 (88.2)	51 (11.8)
Patient factors
Male (%)	336 (77.4)	290 (75.7)	46 (90.2)	0.02
Age (yrs)	61.0±8.6	60.7±8.7	63.2±7.9	0.058
Body mass index (kg/m2)	24.0±2.9	24.1±2.8	23.5±3.0	0.183
Family history of CRC (%)	37 (8.5)	36 (9.4)	1 (2.0)	0.074
Family history of polyps (%)	23 (5.3)	20 (5.2)	3 (5.9)	0.843
Aspirin and/or NSAID use (%)	70 (16.1)	60 (15.7)	10 (19.6)	0.477
Procedure factors
Bowel preparation (%)				0.005
Good or fair	351 (81.0)	317 (83.0)	34 (66.7)
Poor	82 (19.0)	65 (17.0)	17 (33.3)
Endoscopist (%)				0.133
Experienced colonoscopist	230 (53.0)	208 (54.3)	22 (43.1)
Fellow	204 (47.0)	175 (45.7)	29 (56.9)
Withdrawal time (min)	24.2±17.8	23.6±17.7	28.9±17.6	0.043
Diverticular disease (%)	57 (13.1)	50 (13.1)	7 (13.7)	0.894
Failed colonoscopy (%)	7 (1.6)	5 (1.3)	2 (3.9)	0.164
Polyp factors
Interval period (yrs)	1.5±0.8	1.5±0.8	1.6±0.9	0.27
Size (max)	14.5±9.1	14.8±9.3	12.2±7.7	0.054
Site (%)				0.859
Left (DC-R)	255 (59.0)	226 (59.3)	29 (58.0)
Right (C-SF)	176 (41.0)	155 (40.7)	21 (42.0)
Polyp number
Total number (%)	3.7±3.2	3.5±3.1	5.7±3.6	<0.001
1-2	186 (42.9)	180 (47.0)	6 (11.8)	<0.001
3-9	225 (51.8)	189 (49.3)	36 (70.6)
≥10	23 (5.3)	14 (3.7)	9 (17.6)
Number of polyps ≥1 cm	1.0±1.1	1.0±1.0	0.9±1.5	0.593
Pathology (%)				0.166
Adenoma	187 (43.1)	158 (41.3)	29 (56.9)
Villous	83 (19.1)	76 (19.8)	7 (13.7)
High grade	164 (37.8)	149 (38.9)	15 (29.4)

CRC, colorectal cancer; NSAID, nonsteroidal anti-inflammatory drug; DC, descending colon; R, rectum; C, cecum; SF, splenic flexure.