Introduction Faecal Calprotectin (FC) is recommended in primary care (1°care) to help differentiate inflammatory bowel disease (IBD) from irritable bowel syndrome (IBS), although data to justify this practice are limited.1,2 In 2014 we introduced FC to 1°care and in parallel conducted a large prospective observational study to assess the clinical validity and utility of FC in this setting, and develop an integrated decision tool.
Method GPs from 57 local practices were recommended to submit an FC test for patients with suspected or possible IBD. Criteria for testing included age <46 years and a low suspicion of colorectal cancer (CRC). A request form captured patient symptoms and referral intentions. We used the following cut-offs: negative <50 µg/g, indeterminate 50–99 µg/g, positive ≥100 µg/g. We advised referral of patients with elevated FC and GP management for negative tests. Indeterminate tests were repeated. All patients were followed-up for ≥12 months and clinical data captured from 1° and 2°care records. We assessed the impact of FC on referral practice, time to diagnosis and endoscopic activity.
Results 1143 FC tests were submitted (Jan’14-Mar’16), with 761 used in this interim analysis. 458 (59%) were female and median age was 30 years. 50 (7%) patients were diagnosed with IBD, one (0.2%) with an adenoma ≥1 cm and none with CRC. FC≥100 µg/g had a sensitivity=0.92, specificity=0.75, PPV=0.21, NPV=0.99 (AUROC=0.83 [95%CI 0.79–0.87]) for IBD. False negative FC tests occurred in 4 patients later diagnosed with IBD. Red-flag symptoms were reported in 411 (54%) of all patients, 194 (47%) of whom were not referred to 2°care. FC was negative in 520 (68%), and yet 169 (33%) of this group were sill referred to GI services. Multivariable logistic regression demonstrated FC (log10FC=OR 48.2, p<0.01), family history (FHx) of IBD (OR 2.8, p=0.05), and rectal bleeding (OR 3.0, p<0.01) as the best predictors of IBD (R2 0.50). Based on pre-test referral intentions FC saved 252 referrals. The median time from GP referral to IBD diagnosis was 45 days (IQR 25–98).
Conclusion FC is a sensitive and specific test in the primary care setting to distinguish IBD from IBS. It reduces referrals and subsequent endoscopic investigations in patients<46 years including those with red-flag symptoms, but deemed at low risk of CRC. However, a third of patients with a normal FC are still referred. This may reflect lack of confidence in FC and the challenges of managing some IBS patients. We propose a future clinical decision tool integrating FC with rectal bleeding and FHx IBD to facilitate rapid patient identification for secondary care referral.
. Waugh N, et al. doi:10.3310/hta17550(2013)
. NICE DG11 (2013).
Disclosure of Interest None Declared
- FAECAL CALPROTECTIN
- INFLAMMATORY BOWEL DISEASE
- PRIMARY CARE
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