Table 3.
Association between index colonoscopy quality and examination findings and post-colonoscopy colorectal cancer (PCCRC).
| Cases | Controls | ||||||
|---|---|---|---|---|---|---|---|
| Model | At Index Colonoscopy | n | (%) | n | (%) | OR | (95% CI) |
| Total | 1,206 | 634 | |||||
| 1 | No polyp | 434 | (36.0) | 358 | (56.5) | 1.00 | (reference) |
| Polyp | 772 | (64.0) | 276 | (43.5) | 2.68 | (2.15, 3.34) | |
| Complete examination | 1,099 | (91.1) | 620 | (97.8) | 1.00 | (reference) | |
| Incomplete examination | 107 | (8.9) | 14 | (2.2) | 5.52 | (2.98, 10.21) | |
| Adequate bowel preparation | 1,068 | (88.6) | 567 | (89.4) | 1.00 | (reference) | |
| Inadequate bowel preparation | 138 | (11.4) | 67 | (10.6) | 1.11 | (0.78, 1.57) | |
| Total | 917 | 581 | |||||
| 2 | No polyp | 434 | (47.3) | 358 | (61.2) | 1.00 | (reference) |
| Distal polyp, <10 mm | 97 | (10.6) | 80 | (13.8) | 1.06 | (0.73, 1.53) | |
| Distal polyp, ≥10 mm | 59 | (6.4) | 12 | (2.1) | 3.30 | (1.65, 6.58) | |
| Proximal polyp, <10 mm | 176 | (19.2) | 115 | (19.8) | 1.32 | (0.97, 1.81) | |
| Proximal polyp, ≥10 mm | 151 | (16.5) | 16 | (2.8) | 8.18 | (4.59, 14.60) | |
| Total (KPNC only) | 805 | 407 | |||||
| 3 | No adenoma | 432 | (53.7) | 276 | (67.8) | 1.00 | (reference) |
| Adenoma, no advanced histology | 267 | (33.2) | 111 | (27.3) | 1.87 | (1.37, 2.55) | |
| Adenoma, advanced histology | 106 | (13.2) | 20 | (4.9) | 3.23 | (1.83, 5.68) | |
n, number.
Odds ratios (OR) and 95% confidence intervals (CI) were adjusted for age, sex, race/ethnicity, family history of colorectal cancer, year of index colonoscopy, time from index colonoscopy to the cancer diagnosis/reference date, medical region, extent of examination, and adequacy of the bowel preparation (base model).
In Model 1, polyp detection was added to the base model. In Model 2, polyp detection/size/location was added to the base model. In Model 3, adenoma/histology was added to the base model and only Kaiser Permanente Northern California (KPNC) data were utilized because histology status was not available from Kaiser Permanente Southern California.
Adequate bowel preparation was defined as a preparation listed in the index colonoscopy report as satisfactory, good, very good, excellent, or optimal. Inadequate bowel preparation was defined as a preparation listed in the index colonoscopy procedure report as fair, poor, suboptimal, inadequate or unsatisfactory. Complete colonoscopy was defined as to the cecum or terminal ileum. Adenoma with advanced histology was defined as a villous or tubulovillous adenoma.
Colonoscopies detecting both proximal and distal polyps were categorized as proximal for these analyses.