Diagnosing IBD

NICE DG11 faecal calprotectin diagnostic tests for inflammatory diseases of the bowel proposed that faecal calprotectin should be used as part of the assessment of IBD and IBS (NICE, 2013). This consensus document has been developed by experts in the field to assist local health economies to introduce the NICE guidance locally with a view to improve the patient journey and reduce unnecessary referrals to endoscopy services. Increased uptake of the test should produce increased knowledge and evidence, which can be used to enhance NICE DG11.

Amid NHS upheaval in the search for savings, are we missing a huge opportunity by overlooking tried and tested in vitro diagnostic tests?

The Quantum Blue method was a suitable screening test for excluding inflammatory bowel disease. It may be of value to laboratories wishing to offer calprotectin but who do not have sufficient numbers to warrant ELISA methodology or in ‘one stop’ gastrointestinal clinics where an immediate result is required.

Levels and sensitivities of fCal are equal in patients with colonic and small bowel CD. Due to its high sensitivity and negative predictive value, fCal is a useful marker to rule out CD and select patients for endoscopy.

In patients with abdominal discomfort, fecal calprotectin is a useful non-invasive marker to identify clinically significant findings of the gastrointestinal tract, irrespective of age.

Correct use of the test and adherence to usage/referral protocols are likely to lead to fewer referrals to secondary care and consequently fewer investigations with potential cost savings.

Overall accuracy for differentiating IBD from IBS or “other colitis” was the best for Quantum Blue® Calprotectin (97%/91%).

The care pathway for FC in primary care had a 97% NPV and a 40% PPV. This was better than GP clinical judgement alone and doubled the PPV compared with the standard FC cut-off.

FC is beneficial in distinguishing between functional GI conditions (IBS) and organic disease (IBD). In those with IBD, a 250 μg/g cut-off aids in determining clinical disease activity.

The National Institute for Health and Care Excellence has issued new guidelines on the use of faecal calprotectin diagnostic tests for inflammatory diseases of the bowel. As Jason Cunningham explains, these guidelines may have substantial impact and cause the number of test requests to rocket.

The use of F-calprotectin as a screening test substantially could reduce the number of invasive measurements necessary in the diagnostic work-up of patients with suspected IBD, as well as the associated costs

“We conducted a systematic review of the published literature regarding fecal calprotectin to evaluate its potential as a noninvasive marker of neutrophilic intestinal inflammation.”

Testing for faecal calprotectin is a useful screening tool for identifying patients who are most likely to need endoscopy for suspected inflammatory bowel disease. The discriminative power to safely exclude inflammatory bowel disease was significantly better in studies of adults than in studies of children.

Faecal calprotectin is now playing a major role in the investigation and diagnosis of patients presenting to the physician with lower gastrointestinal symptoms and can obviate the need for costly invasive investigations in selected patients.

This article summarizes the current literature on the use of fecal calprotectin in clinical practice.

Faecal calprotectin can be a highly sensitive way of detecting IBD, although there are inevitably trade-offs between sensitivity and specificity, with some false positives (IBS with positive calprotectin) if a low calprotectin cut-off is used. In most cases, a negative calprotectin rules out IBD, thereby sparing most people with IBS from having to have invasive investigations, such as colonoscopy.