Els van de Vijver

30 Table 3 : Added value of the “clinical eye” or faecal calprotectin testing in a population of children and teenagers suspected of IBD Characteristics “Clinical eye” of the paediatrician Faecal calprotectin Faecal calprotectin (gastrointestinal infections excluded) n 117 117 104 True positives 42 42 42 True negatives 49 55 50 False positives 26 20 12 False negatives 0 0 0 Pre-test probability 36% 36% 40% Sensitivity (95% CI) 100% (92 to 100%) 100% (92 to 100%) 100% (92 to 100%) Specificity (95% CI) 65% (53 to 76%) 73% (62 to 83%) 81% (69 to 90%) Positive likelihood ratio (95% CI) 2.9 (2.1 to 3.9) 3.8 (2.6 to 5.5) 5.2 (3.1 to 8.6) Negative likelihood ratio (95% CI) 0 0 0 Post-test probability given a positive test result (95% CI) 62% (49 to 73%) 68% (55 to 79%) 78% (64 to 88%) Post-test probability given a negative test result (95% CI) 100% (93 to 100%) 100% (93 to 100%) 100% (93 to 100%) Scenario analysis When the decision to schedule patients for endoscopic evaluation is left to the paediatrician’s discretion (as was the case in our study), 38% of the children and teenagers subjected to ileocolonoscopy had a negative result ( Table 4 ). Chapter 2