Table 2.
Metachronous findings by index colonoscopy findings characterized by high risk adenoma and serrated polyp (size and histology) among 4,015 NHCR participants with 2 colonoscopies (1/2004 – 6/2015)
| Metachronous | |||||
|---|---|---|---|---|---|
| HRA | SP ≥ 1 cm | ||||
| Total N = 4,015 | No N = 3,716 (92.6%) | Yes N = 299 (7.4%) | No N = 3,966 (98.8%) | Yes N = 49 (1.2%) | |
| Index findings | N | N (row %) | N (row %) | N (row %) | N (row %) |
| Classification based on size of serrated polyps on index colonoscopy | |||||
| HRA (N =817) | p<0.0001 | p<0.0001 | |||
| SP ≥ 1 cm | 18 | 14 (77.7) | 4 (22.2) | 16 (88.8) | 2 (11.2) |
| SP < 1 cm | 140 | 111 (79.3) | 29 (20.7) | 139 (99.3) | 1 (0.7) |
| Unknown SP Size | 56 | 45 (80.4) | 11 (19.6) | 55 (98.2) | 1 (1.8) |
| No SP | 603 | 493 (81.8) | 110 (18.2) | 597 (99.0) | 6 (1.0) |
| No adenoma (N = 3,198) | |||||
| SP ≥ 1 cm | 65 | 63 (96.9) | 2 (3.1) | 57 (87.7) | 8 (12.3) |
| SP < 1 cm | 452 | 436 (96.5) | 16 (3.5) | 446 (98.7) | 6 (1.3) |
| Unknown SP Size | 285 | 274 (96.1) | 11 (3.9) | 278 (97.5) | 7 (2.5) |
| No SP | 2,396 | 2,280 (95.2) | 116 (4.8) | 2,378 (99.3) | 18 (0.7) |
| Classification based on histology of serrated polyps on index colonoscopy | |||||
| HRA (N =817) | p<0.0001 | p<0.0001 | |||
| STSA | 28 | 15 (53.6) | 13 (46.4) | 27 (96.4) | 1 (3.6) |
| HP Only | 186 | 155 (83.3) | 31 (16.7) | 183 (98.4) | 3 (1.6) |
| No SP | 603 | 493 (81.8) | 110 (18.2) | 597 (99.0) | 6 (1.0) |
| No adenoma (N = 3,198) | |||||
| STSA | 104 | 101 (97.1) | 3 (2.9) | 94 (90.4) | 10 (9.6) |
| HP Only | 698 | 672 (96.3) | 26 (3.7) | 687 (98.4) | 11 (1.6) |
| No SP | 2,396 | 2,280 (95.2) | 116 (4.8) | 2,378 (99.3) | 18 (0.7) |
Abbreviations: NHCR = New Hampshire Colonoscopy Registry, HRA=high risk adenoma, SP = serrated polyp, STSA = sessile and traditional serrated adenoma, HP = hyperplastic polyp