Faecal calprotectin as part of standardised assessment tool of suspected irritable bowel syndrome (IBS): a novel investigative algorithm

Abstract

Introduction There is enormous variability in the referral rates for IBS from GPs and this relates to patient and physician factors. 1 IBS patients tend to wait longer for appointments and hence a standardised algorithm which includes faecal calprotectin (FC) might aid in the rapid assessment of IBS in secondary care. FC has been shown to consistently differentiate IBS from IBD because it has excellent negative predictive value in excluding organic pathology. 2 Methods To assess the effi cacy of diagnostic algorithm (using FC) for assessment of IBS in a pilot study using patients already referred to hospital GI clinics. Patients were included if the GP suspected IBS (age group 18-50),without alarm symptoms (weight loss, rectal bleeding etc) at time of referral. Initial assessment was in a nurse-led clinic using a standardised algorithm consisting of questionnaire and baseline investigations (FC, FBC, ESR, CRP, albumin, IgA and TTG). FC level < 100 mcg/g was considered normal. 3 4 week review was undertaken by a doctor and those with abnormal results were transferred to the GI clinic. 1-year assessment was undertaken on all study patients, reviewing fi nal diagnosis and hospital visits. Clinical diagnosis by nurse and doctor before results of FC and blood tests were compared. Co-primary end-points were the positive predictive value (PPV) of the algorithm in diagnosing IBS and the added benefi t of FC in excluding organic pathology.

High negative predictive value of a normal faecal calprotectin in patients with symptomatic intestinal disease

“…And in a recent meta-analysis it had been concluded that measuring ‘faecal calprotectin is a useful screening tool for identifying patients who are most likely to need endoscopy for suspected IBD.’9 The authors however expressed reservations about its utility in primary care. To date, no studies have been performed in the primary care setting to refute this 10 11…”

Faecal calprotectin testing for differentiating amongst inflammatory and non-inflammatory bowel diseases: systematic review and economic evaluation

“…The Cardiff data show that a considerable proportion of referrals by GPs are to confirm IBS (by exclusion of IBD). 38 So the main value of calprotectin testing may be to confirm presumptive diagnoses of IBS, and that can be done in general practice. Other studies (Rotherham unpublished) report that > 60% of colonoscopies in the 'pre-calprotectin era' showed no pathology.…”

“…In one small study (54 patients) from Cardiff, the main reason for referral was diagnostic uncertainty (37/54) but the second reason was for 'confirmation of IBS' (17/54). 38 In various studies, the proportion of patients referred for further investigation, in whom abnormal findings are reported on colonoscopy, is low. Kok et al 39 noted reports that only 22-37% had organic bowel disease (OBD).…”