Introduction Measurement of faecal calprotectin (FC) may identify those harbouring inflammatory bowel disease (IBD). Use of the test is supported by NICE guidance (DG11) but evidence of its performance, in “real-life”, in patients presenting to primary care, is limited.
Aim To assess the yield of IBD from FC testing in primary care.
Method FC testing (Immunodiagnostics Phical Calprotectin ELISA) was made available to clinicians in October 2013. The results of all FC assays from 1.10.13 to 28.2.14 were reviewed retrospectively with results of GI investigations.
Results Of FC measurements undertaken in 526 patients, 26 could not be identified on the local patient administration system, 57 were initiated in secondary care, 23 had known IBD and outcomes were not available for 22 patients with a raised FC (median 90 μg/g); range 54–995). These were excluded.
398 patients had FC requested in primary care (158 male; median age 42; range 6–91). FC was “positive” (>50 μg/g) in 132/398 (33.2%; median age 44 (range 6–91); median FC 128.5 μg/g (51–1770).
122/132 with positive FC underwent further investigation; 94 (77%) had lower GI endoscopy: IBD (7), colorectal cancer (2), adenoma (8), nil significant (77). 87/94 had lower GI endoscopy for a false positive FC (no IBD). 49/266 FC-negative patients also underwent lower GI endoscopy (median age 47; range 19–76) finding IBD (2), diverticulitis (1), adenomas (2), nil significant (43). 3/266 FC negative patients had IBD.
IBD was diagnosed in 11/398 (2.3%; 4 ulcerative colitis (UC), 3 Crohn’s disease (CD), 2 collagenous colitis, 2 lymphocytic colitis (Table 1)). 8/11 were FC positive (range 67–1170); 3 were FC negative. At a 50 μg/g threshold, sensitivity for detecting IBD was 72.7%, specificity 68%, positive predictive value (PPV) 6.1%, negative predictive value 98.9%.
Conclusion FC testing in primary care has lower sensitivity and specificity than in secondary care and poor PPV for detecting IBD. False positive FC is associated with more lower GI investigation than previously estimated. This experience differs from data used to inform NICE DG11. Strategies to target use to those with higher pre-test probability of IBD are needed.
Disclosure of interest S. Conroy: None Declared, M. Hale: None Declared, S. Cross: None Declared, K. Swallow: None Declared, R. Sidhu: None Declared, R. Sargur: None Declared, A. Lobo Consultant for: Takeda UK and Vifor Pharma.