Objectives: To assess the clinical effectiveness of faecal calprotectin (FC) testing for distinguishing between organic gastrointestinal diseases (organic GID), like inflammatory bowel disease (IBD), and functional gastrointestinal disorders (functional GIDs).
Study design: Studies that assessed the accuracy of FC testing for differentiating between IBD or organic GID and functional GIDs were reviewed. Articles published in English during January 1998 – June 2018 that compared diagnostic FC testing in medical care and outpatient hospital settings with a reference test and employed the quality enzyme‐linked immunosorbent FC assay method with a cut‐off of fifty or 100 μg/g faeces were included. Study quality was assessed with QUADAS‐2, an evidence‐based quality assessment tool for diagnostic accuracy studies.
Data sources: MEDLINE and EMBASE; reference lists of screened articles.
Data synthesis: Eighteen relevant studies were identified. For distinguishing patients with organic GID (including IBD) from those with functional GIDs (16 studies), the estimated sensitivity of FC testing was 81% (95% CI, 74–86%), the specificity 81% (95% CI, 71–88%); area under the curve (AUC) was 0.87. For distinguishing IBD from functional GIDs (ten studies), sensitivity was 88% (95% CI, 80–93%), specificity 72% (95% CI, 59–82%), and AUC 0.89. Assuming a population prevalence of organic GID of 1%, the positive predictive value was 4.2%, the negative predictive value 100%. The difference in sensitivity and specificity between FC testing cut‐offs of fifty μg/g and 100 μg/g faeces wasn’t statistically significant (P = 0.77).