Faecal calprotectin levels can differentiate between inflammatory and non-inflammatory bowel diseases

Irritable bowel syndrome (IBS) is a common form of non-inflammatory bowel disease. IBS is painful and can result in a lowered quality of life, but does not cause permanent damage to the intestines. On the other hand, inflammatory bowel diseases (IBD) such as Crohn’s Disease or Ulcerative Colitis are associated with inflammation in the intestinal tract that may require pharmaceuticals or even surgery to get it under control.

The symptoms of IBD and IBS are similar, therefore differentiating the two can be difficult, often requiring examination by endoscopy. It has been proposed that faecal calprotectin, a stable protein that accumulates in the bowels in response to inflammation, can be used to more quickly and more comfortably differentiate between IBD and IBS.

In this report SBU summarises and remarks on a systematic review from the National Institute for Health Research (NIHR) in Great Britain, published in 2013 [1]. The authors of the review systematically assessed the use of faecal calprotectin as a marker to differentiate between inflammatory and non-inflammatory bowel diseases.

Summary

Faecal calprotectin is a useful marker for differentiating between inflammatory and non-inflammatory bowel diseases, as long as other stomach or intestinal infections have been ruled out. Adoption of this test could reduce the proportion of patients needing to undergo invasive investigations, such as colonoscopy, and could result in lowered health care costs.

Remarks from SBU

• The results from the original report are based on studies of patients younger than 60 years of age, who have suffered from abdominal or intestinal symptoms for at least six weeks, for whom blood tests had excluded gluten intolerance, and who do not have typical IBD alarm symptoms (bloody bowel movements, unintended weight loss, and fever). In Sweden, this patient population is estimated to make up as much as half of all patients who present to the primary health care system with abdominal or intestinal problems. Systematic screening of this population for faecal calprotectin levels would significantly help people get the right diagnosis and reduce the number of colonoscopies performed.
• Health economic analysis indicated that faecal calprotectin tests would lead to savings, as well as marginal improvements in the quality adjusted live years (QALY) in both the primary and specialist health care sectors. This calculation was based on the fact that the faecal calprotectin test were performed prior to colonoscopy, eliminating the need for those with a negative result to submit to such an invasive test. Therefore the savings stem primarily from the reduction in the number of colonoscopies performed. A sensitivity analysis shows that even with a limited increase in the calculated patient population, the faecal calprotectin test would likely be cost effective.
• The choice of cut-off will affect which patients will be examined using colonoscopies. The cutoff for normal is 50 micrograms calprotectin per gram of faeces using ELISA. However, a grey zone exist between 50–150 μg/g for adults, and up to 200 μg/g for children. This highlights how faecal calprotectin tests should be used as a support, in combination with the overall clinical assessment of a patient, to determine which patients need to be examined using colonoscopy.
• Faecal calprotectin is not only elevated in IBD. Bacterial infections of the gastrointestinal tract (gastroenteritis) or ingestion of non-steroidal anti-inflammatory drugs (NSAID) can result in slightly elevated faecal calprotectin levels, resulting in false positives. Even heavy abdominal bleeding and menstruation, or bacterial respiratory infections can result in elevated faecal calprotectin levels.
• As there is a lower prevalence of IBD in primary care relative to specialist care, Swedish studies focused on primary care patients who present with abdominal pain and or persistent diarrhoea are needed. Such studies should focus on the diagnostic outcomes comparing the faecal calprotectin test compared to either endoscopy or intestinal biopsy identification.
• Long term studies of people with slightly elevated faecal calprotectin levels (50–200 μg/g) are also needed to follow up how these levels change over time. Such studies would also allow the discovery of any negative effects that might result from a delayed endoscopic examination.