Table 4. Positive predictive value (PPV) (%) of FOBT+ colonoscopy for cancer and for significant neoplasiaa and number needed to scope (NTS) to find a cancer or a significant neoplasia by screening strategy and difference with the reference strategyb.
|
2–day strategy
|
|||
|---|---|---|---|
| Cutoff | 1-day strategy | (at least one sample with positive result) | (both samples with positive results) |
| (A) PPV × 100 colonoscopies | |||
| Cancer | |||
| ⩾80 ng ml−1 | 5.9 | 4.7** | 9.1 |
| −1.0 (−3.3 to 1.3) | −2.2 (−4.2 to −0.1) | +2.2 (−0.8 to 5.3) | |
| ⩾100 ng ml−1 | 6.9b | 5.7 | 10.4*** |
| (reference) | −1.2 (−3.4 to 0.9) | +3.5 (0.1 to 6.9) | |
| ⩾120 ng ml−1 | 7.6 | 6.2 | 11.6**** |
| +0.7 (−1.9 to 3.3) | −0.7 (−3.0 to 1.6) | +4.7 (1.0 to 8.3) | |
| Significant neoplasia | |||
| ⩾80 ng ml−1 | 42.7 | 36.5 | 58.5 |
| −3.2 (−7.8 to 1.4) | −9.4 (−13.6 to −5.2)c | +12.6 (7.2–18.1)c | |
| ⩾100 ng ml−1 | 45.8 | 38.9 | 62.4 |
| (reference) | −6.9 (−11.3 to −2.6)c | +16.6 (10.9–22.3)c | |
| ⩾120 ng ml−1 | 48.4 | 41.3***** | 65.8 |
| +2.6 (−2.3 to 7.6) | −4.5 (−9.0 to 0.0) | +20.0 (14.1–25.8)c | |
| (B) NTSd | |||
| Cancer | |||
| ⩾80 ng ml−1 | 17.0 (13.6–22.6) | 21.2 (17.3–27.6) | 11.0 (8.6–15.1) |
| ⩾100 ng ml−1 | 14.5 (11.6–19.4)b | 17.7 (14.4–23.0) | 9.6 (7.5–13.4) |
| (reference) | |||
| ⩾120 ng ml−1 | 13.2 (10.5–17.6) | 16.2 (13.1–21.0) | 8.6 (6.8–12.0) |
| Significant neoplasia | |||
| ⩾80 ng ml−1 | 2.3 (2.2–2.5) | 2.7 (2.6–2.9) | 1.7 (1.6–1.9) |
| ⩾100 ng ml−1 | 2.2 (2.0–2.4)b | 2.6 (2.4–2.8) | 1.6 (1.5–1.7) |
| (reference) | |||
| ⩾120 ng ml−1 | 2.1 (1.9–2.2) | 2.4 (2.3–2.6) | 1.5 (1.4–1.6) |
Statistical comparison of strategies (adopting Bonferroni correction for multitesting). 95% CI (confidence interval) of difference is given in brackets.
a
Significant neoplasia: cancer+advanced adenoma (any adenoma larger than 9 mm, and/or with a villous histological component higher than 20%, and/or with severe dysplasia).
b
Reference strategy: 1-day and cutoff ⩾100 ng ml−1.
c
Differences among strategy and the reference were statistically significant at P<0.00625 (threshold for significance after Bonferroni correction).
Non-significant at P<0.00625, *P=0.0277, **P=0.0312, ***P=0.0063, ****P=0.0485.
d
NTS: number of FOBT+colonoscopies needed to find a cancer or a significant neoplasia.