Introduction NICE guidelines¹ have suggested the introduction of an ‘indeterminate’ range in faecal calprotectin that would include values that are above the reference range but not clinically significant in assessing for inflammatory bowel disease (IBD).² BSG guidance has suggested that the value of faecal calprotectin above which colonoscopy is required should be determined by local audit. This audit is designed to determine that value for the County Durham and Darlington population.

Method A total of two-hundred colonoscopies requested at County Durham and Darlington Foundation Trust (CDDFT) between 1^stDecember 2014 and 21^st September 2015 with an indication of ‘raised faecal calprotectin’ were analysed. We looked at: the value of faecal calprotectin; findings at colonscopy; histological findings; and findings of small bowel imaging. CCDFT uses the EliA Calprotectin test and a raised value is defined as >50 mg/kg.

Results Fifty-five out of 200 (27.5%) of patients had an endoscopic, histological or radiological abnormality. 25 of the 47 patients with endoscopic inflammation did not have significant histological findings. All patients with abnormal histological or radiological findings had a faecal calprotectin >69 mg/kg.

Patients with a faecal calprotectin <200 mg/kg were more likely to have comparatively mild diagnoses. The greatest proprotion of patients with abnormal findings had a faecal calprotectin >200 mg/kg (30/38=78.9%). All patients with a definite diagnosis of IBD had a faecal calprotectin >147 mg/kg and the majority of these patients (18/22) had a faecal calprotectin >300 mg/kg.

Fifty-seven patients had a faecal calprotectin >300 mg/kg but normal histology following colonoscopy. Of these 57 patients, 19 had subsequent small bowel imaging of which 4 patients had abnormal findings.

Conclusion Based on these findings, we would suggest that the indeterminate value of faecal calprotectin for CDDFT patients is between 50 mg/kg and 200 mg/kg. Colonoscopy should be considered in these patients depending on clinical history. Colonoscopy should be offered to those with a faecal calprotectin >200 mg/kg. In addition to this, small bowel imaging should be considered in those with a faecal calprotectin >300 mg/kg who have normal findings at colonoscopy.

References

1. . National Institute for Health and Clinical Excellence. Faecal Calprotectin diagnostic tests for inflammatory diseases of the bowel. NICE Diagnostics guidance. London: NICE; 2013: https://www.nice.org.uk/guidance/dg11 (accessed 20th January 2017)

2. . Bristish Society of Gastroenterology. BSG Guidance on the use of faecal calprotectin testing in IBD.London: BSG; 2016: http://www.bsg.org.uk/clinical-guidance/ibd/bsg-guidance-on-the-use-of-faecal-calprotectin-testing-in-ibd.html (accessed 20th January 2017)

Disclosure of Interest None Declared