Performance of blood tests in diagnosis of inflammatory bowel disease in a specialist clinic.

AIMS: To determine the reliability of a panel of blood tests in screening for ulcerative colitis and Crohn's disease. METHODS: The subjects were 153 children referred to a paediatric gastroenterology department with possible inflammatory bowel disease (IBD). Of these, 103 were found to have IBD (Crohn's disease 60, ulcerative colitis 37, indeterminate colitis 6). The 50 without IBD formed the controls. Blood tests evaluated included haemoglobin, platelet count, ESR, CRP, and albumin. Receiver operating characteristic curves were used where possible to determine optimal threshold values. Binary logistic regression analysis was used to investigate the five screening tests in combination, and a stepwise method was used to find the best test combination. RESULTS: The optimal screening strategy used a combination of haemoglobin and platelet count and "1 of 2 abnormal" as the criterion for positivity. This was associated with a sensitivity of 90.8% (95% CI 83.3 to 95.7%), a specificity of 80.0% (95% CI 65.7 to 89.8%), and positive and negative predictive values of 94.4% and 75.9% respectively. CONCLUSIONS: Haemoglobin and platelet count provide a useful screening test combination for patients with suspected IBD. These tests are not completely reliable however. If clinical suspicion is high further investigations are required. [ABSTRACT FROM AUTHOR]