Fig. 1.

Positive predictive values (95 % confidence intervals) for gastro-oesophageal cancer in men and women over 55 years of age for individual risk markers and for pairs of risk markers in combination. The top figure in each cell is the positive predictive value when both features are present. The two smaller figures represent the 95 % CIs for the positive predictive value. These have not been calculated when any cell in the 2×2 table was below 5 (invariably this was because too few controls had both features). The yellow shading is for pairs of symptoms with a positive predictive value over 1 %, the amber shading is when the positive predictive value is above 2.0 %, and the red shading is for positive predictive values above 5.0 %. The cells along the diagonal relate to the positive predictive value when the same feature has been reported twice. Thus the back pain/back pain intersect is the positive predictive value for pancreatic cancer when a patient has attended at least twice with back pain