17 Optimising the use of faecal calprotectin for early diagnosis of IBD in primary care

Abstract

Background: Faecal calprotectin ELISA (FC) is an exquisitely sensitive and specific test of intestinal inflammation and may have a role in distinguishing early IBD from other GI disorders (IBS) presenting in primary care. Previous data has shown that diagnostic uncertainty for symptomatic patients with FC between 50-150 μg/g might be resolved by a strategy of repeat testing 6-8 weeks later. The AIM of this study was to evaluate the safety and diagnostic utility of this strategy in patients with elevated FC levels in primary care. Methods: Study population: All patients with a FC results within the pathology faecal calprotectin data set from June 2009-2012 (n = 9123). Patient data were cross checked with electronic patient records, radiology (PACS), endoscopy and histology data sets for SnoMed CT codes for IBD (T655260 T67000-6893). Exclusion criteria: previous diagnosis of IBD, and aged 150-3000 μg/g. In the latter population, there were 13 new diagnoses of IBD (9 female, 7 with UC), in whom mean FC increased from 933 to 1666 μg/g (sem ±200) (ns) on repeat testing prior to specialist referral. In contrast, FC values fell rapidly in 37 patients with presumed infectious enteritis: initial mean FC decreased from 682 to 53 μg/g (sem ±155) (p < 0.05). In 66 patients with minimally elevated FC levels (50-150 μg/g), none developed IBD during 2years follow up, and repeat FC testing showed a non-significant fall in FC from a mean 88 to 65 mg/g (sem ±5) (ns), with sub-group analysis suggesting regression towards the mean. Conclusions: These data demonstrate that, in primary care, a strategy of repeat FC testing facilitates the diagnosis of IBD and the distinction between IBD and infectious enteritis. These data also show that repeat FC testing in patients with minimally elevated FC values is a safe strategy for patients with FC values in the 'grey-zone'.