Can the CalproQuest predict a positive Calprotectin test? A prospective diagnostic study

BACKGROUND: Diagnosis of inflammatory bowel disease (IBD) in primary care (PC) is challenging and associated with a considerable diagnostic delay. Using a calprotectin test for any PC patient with abdominal complaints would cause significant costs. The 8-item-questionnaire CalproQuest was developed to increase the pre-test probability for a positive Calprotectin. It is a feasible instrument to assess IBD in PC, but has not yet been evaluated in clinical routine. This study, therefore, aimed to validate whether the CalproQuest increases pretest-probability for a positive fecal Calprotectin. METHODS: Prospective diagnostic trial. The CalproQuest consists of 4 major and 4 minor questions suggestive for IBD. It is considered positive if ≥ 2 major or 1 major and 2 minor criteria are positive. Primary outcome: Sensitivity and specificity of the CalproQuest for Calprotectin levels ≥ 50 μg/g and for positive IBD diagnosis among patients referred to endoscopic evaluation at secondary care level. Secondary finding: Patient-reported diagnostic delay. RESULTS: 156 patients from 7 study centers had a complete CalproQuest and fecal Calprotectin test. The sensitivity and specificity of CalproQuest for Calprotectin ≥ 50 μg/g was 36% and 57%. The sensitivity and specificity of the CalproQuest for positive IBD diagnosis was 37% and 67%. The diagnostic delay was 61 months (SD 125.2). CONCLUSION: In this prospective diagnostic study, the sensitivity and specificity of CalproQuest for Calprotectin levels ≥ 50 μg/g and positive IBD diagnosis were poor. Additional prospective studies concerning the ideal cut-off values, validity and cost-effectiveness of a combined use with the Calprotectin test in the PC setting are necessary.