The diagnostic value of symptom combinations and the characteristics of rectal bleeding for colorectal cancer in primary care.
| Symptoms | Numbers | Predictive value | Likelihood ratio (95% CI) | Sensitivity | Specificity |
|---|---|---|---|---|---|
| Bleeding and CIBH | 11/119 | 9.2 | 2.361 (2.046 to 2.725) | 100 | 55 |
| Bleeding and no CIBH | 0/147 | 0 | |||
| Bleeding and CIBH (loose +/− frequent) | 10/83 | 12.1 | 1.345a (1.071 to 1.689) | 91 | 32 |
| Bleeding and CIBH (hard +/− infrequent) | 1/36 | 2.8 | |||
| Bleeding and no perianal symptoms | 7/63 | 11.1 | 2.898 (1.752 to 4.792) | 64 | 78 |
| Bleeding and perianal symptoms | 4/203 | 1.97 | |||
| Bleeding, CIBH and abdominal pain | 6/67 | 9 | 0.966a (0.549 to 1.697) | 55 | 44 |
| Bleeding, CIBH and no abdominal pain | 5/52 | 9.6 | |||
| Dark blood | 3/31 | 9.7 | 2.133 (0.765 to 5.946) | 27 | 87 |
| Bright blood | 8/199 | 4 | |||
| Aged ≥60 years | 8/155 | 5.2 | 1.524 (1.042 to 2.229) | 73 | 52 |
| Aged ≤59 | 3/164 | 1.8 | |||
| Blood on paper only | 2/82 | 2.4 | 0.580 (0.163 to 2.057) | 18 | 69 |
| Blood in pan and on paper | 9/184 | 4.9 | |||
| Large volume of blood | 1/79 | 1.3 | 0.297 (0.045 to 1.944) | 9 | 69 |
| Small volume of blood | 10/187 | 5.3 | |||
| First time rectal bleeding | 5/106 | 4.7 | 1.148 (0.590 to 2.231) | 45 | 60 |
| Not first time bleeding | 6/160 | 3.8 | |||
| Blood mixed with the stool | 1/33 | 3 | 0.724 (0.109 to 4.827) | 9 | 87 |
| Blood not mixed with the stool | 10/233 | 4.3 | |||
Total cancers in study: 11/319 = 3.4%. Diagnostic yield for cancer in patients sigmoidoscoped: 11/219 = 5%. Pre-test probability or positive predictive value of rectal bleeding in cancer for patients answering questionnaire or sigmoidoscoped: 11/266, 4.1% [95% CI = 2.1 to 7.3]).
↵a Likelihood ratio derived using only patients with rectal bleeding and a change in bowel habit using pre-test probability of 9.2%. CIBH = change in bowel habit.