Fig. 4

Sensitivities and specificities of risk prediction models and guidelines within the same population. Highlighted boxes indicate guidelines. In NICE 1, 2 and 3 a score of 1 was given for fulfilling any of the NICE high-risk criteria and a score of 100 for a positive faecal occult blood test (FOBT), abnormal rectal examination or abdominal mass. For NICE 1 a single consultation with diarrhoea or change in bowel habit (CIBH) was assumed to indicate a 6 week change. For NICE 2 two consultations for diarrhoea between 35 and 119 days apart were taken to indicate a change in bowel habit for > 6 weeks (CIBH coding not used). For NICE 3 two consultations for diarrhoea between 35 and 119 days apart, or a single consultation with CIBH, were taken to indicate a change in bowel habit for > 6 weeks. WNS – Weighted Numerical Score developed by Selvachandran et al. 2002 with cut-offs of 40, 50, 60 or 70. DOH – Department of Health