PPVs (95% CI) for colorectal cancer (CRC) or inflammatory bowel disease (IBD) in males and females aged 18–49 years for individual risk markers and for pairs of risk markers in combination. The top figure in each cell is the PPV (95% CI) when both features are present. CI have not been calculated when any cell in the 2 × 2 table was <5 (invariably, this was because too few controls had both features). The yellow shading is for features with a PPV >1%; and the red for PPV >3% (see Discussion for reasoning). The cells along the diagonal relate to the PPV when the same feature has been reported twice. Thus, the abdominal pain/abdominal pain intersect is the PPV for CRC/IBD when a patient has attended at least twice with abdominal pain. PPV = positive predictive value.
↵aFeatures that did not retain independent significance in multivariable analysis in the CRC/IBD population. All associations in the above table had a P-value of <0.001. CRC = colorectal cancer. IBD = inflammatory bowel disease. LR = likelihood ratio. PPV = positive predictive value.