Predictive value of signs and symptoms for colorectal cancer in patients with rectal bleeding in general practice

The aim of the study is to determine the diagnostic value of(combinations of) signs, symptoms and simple laboratory testresults for colorectal cancer in patients with rectal bleedingpresenting in general practice. Initial complaints and findingswere compared with the final diagnoses based on clinical follow-upafter at least 1 year. Patients studied were those presentingovert rectal bleeding to the general practitioner (83 GPs inthe South of the Netherlands). Outcome measures are sensitivity,specificity, predictive values, odds ratios and a predicitionmodel derived from multiple logistic regression analysis. Age,change in bowel habit and blood mixed with or on stool showa statistically significant independent value in the discriminationbetween patients with a low and those with a high probabilityof colorectal cancer. Many other variables did not show predictivevalue. The prediction model has a sensitivity of 100% and aspecificity of 90%. Although the number of patients with colorectalcancer is small (n=9) it was possible to identify three characteristicswhich can be helpful in the prediction of presence or absenceof colorectal cancer in general practice. Application of themodel presented might prevent 90% of ‘unnecessary’invasive diagnostic procedures for patients with rectal bleedingwho do not have colorectal cancer (true negative). Testing theperformance of the model in other general practice populationsis recommended.