Characteristics of the patients at randomisation
| Characteristics | 2-examination group (n=1087) | 1-examination group (n=1079) | Both groups (n=2166) |
| Age, years, mean (SD) | 58.6 (6.9) | 58.4 (7.2) | 58.5 (7.1) |
| n (%) of patients | |||
| Age | |||
| <60 years | 535 (49.2) | 539 (50.0) | 1074 (49.6) |
| ≥60 years | 552 (50.8) | 540 (50.0) | 1092 (50.4) |
| Gender | |||
| Male | 726 (66.8) | 706 (65.4) | 1432 (66.1) |
| Female | 361 (33.2) | 373 (34.6) | 734 (33.9) |
| Baseline colonoscopy indication | |||
| Positive FIT | 368 (33.9) | 384 (35.6) | 752 (34.7) |
| Postpolypectomy surveillance | 236 (21.7) | 205 (19.0) | 441 (20.4) |
| Endoscopic treatment* | 178 (16.4) | 193 (17.9) | 371 (17.1) |
| Symptomatic† | 124 (11.4) | 138 (12.8) | 262 (12.1) |
| Screening | 129 (11.9) | 115 (10.7) | 244 (11.3) |
| Barium enema abnormality | 30 (2.8) | 25 (2.3) | 55 (2.5) |
| Others | 22 (2.0) | 19 (1.8) | 41 (1.9) |
| Family history of CRC‡ | |||
| Present | 166 (15.3) | 153 (14.2) | 319 (14.7) |
| Absent | 921 (84.7) | 926 (85.8) | 1847 (85.3) |
| Past history of polypectomy§ before enrolment | |||
| Present | 300 (27.6) | 253 (23.4) | 553 (25.5) |
| Absent | 787 (72.4) | 826 (76.6) | 1613 (74.5) |
| Bowel preparation¶ | |||
| Excellent/good | 2055 (94.5) | 2065 (95.7) | 4120 (95.1) |
| Fair/poor | 119 (5.5) | 93 (4.3) | 212 (4.9) |
| Size of largest adenoma before randomisation** | |||
| Small (≤5 mm) | 375 (34.5) | 371 (34.4) | 746 (34.4) |
| Medium (6–9 mm) | 362 (33.3) | 379 (35.1) | 741 (34.2) |
| Large (≥10 mm) | 350 (32.2) | 329 (30.5) | 679 (31.3) |
| Morphology†† | |||
| Polypoid (≥10 mm) | 273 (25.1) | 257 (23.8) | 530 (24.5) |
| Flat (<10 mm) | 716 (65.9) | 697 (64.6) | 1413 (65.2) |
| Depressed | 24 (2.2) | 28 (2.6) | 52 (2.4) |
| LST-G | 47 (4.3) | 37 (3.4) | 84 (3.9) |
| LST-NG | 38 (3.5) | 56 (5.2) | 94 (4.3) |
| Mean no of adenomas/patient | |||
| 3.5 | 3.3 | 3.4 | |
| No of adenomas | |||
| 1–2 | 528 (48.6) | 565 (52.4) | 1093 (50.5) |
| 3–4 | 293 (27.0) | 270 (25.0) | 563 (26.0) |
| ≥5 | 266 (24.5) | 244 (22.6) | 510 (23.5) |
| Adenoma detection rate | |||
| First colonoscopy | 884 (81.3) | 877 (81.3) | 1761 (81.3) |
| Advanced neoplasia (AN)‡‡ | 247 (22.7) | 255 (23.6) | 502 (23.2) |
| Second colonoscopy | 477 (43.9) | 486 (45.0) | 963 (44.5) |
| AN | 12 (1.1) | 26 (2.4) | 38 (1.8) |
| Histology of worst lesion before randomisation | |||
| Low-grade dysplasia | 824 (75.8) | 845 (78.3) | 1669 (77.1) |
| High-grade dysplasia | 263 (24.2) | 234 (21.7) | 497 (22.9) |
| Villous component§§ | |||
| Present | 71 (6.5) | 67 (6.2) | 138 (6.4) |
| Absent | 1016 (93.5) | 1012 (93.8) | 2028 (93.6) |
| Large serrated lesion (≥10 mm, Rt-sided¶¶) | |||
| Present | 11 (1.0) | 14 (1.3) | 25 (1.2) |
| Absent | 1076 (99.0) | 1065 (98.7) | 2141 (98.8) |
| No of examinations after enrolment until colon was polyp-free | |||
| 2 | 1050 (96.6) | 1038 (96.2) | 2088 (96.4) |
| ≥3 | 37 (3.4) | 41 (3.8) | 78 (3.6) |
*Referred from other hospitals for endoscopic treatment.
†Abdominal pain, constipation and bloody stool, among others.
‡First degree relative with CRC.
§Past history of polypectomy for neoplastic lesions before enrolment.
¶Data from all first/ second colonoscopy.
**Data from past history of colonoscopy and first/ second colonoscopy.
††Polypoid; 0-Ip, 0-Isp, 0-Is type, Flat; 0-IIa type, Depressed; 0-IIa+IIc, 0-IIc type.
‡‡Any lesion with low-grade dysplasia ≥10 mm, high-grade dysplasia.
§§Tubulovillous adenoma and villous tumour.
¶¶Caecum, ascending colon, transverse colon.
AN, advanced neoplasia; CRC, colorectal cancer ; FIT, fecal immunochemical test; LST-G, laterally spreading tumour, granular type; LST-NG, laterally spreading tumour, non-granular type.