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Low diagnostic accuracy of confocal laser endomicroscopy in detecting wheat sensitivity in non-celiac IBS patients

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Dr Philip Abraham, Consultant Gastroenterologist, P. D. Hinduja National Hospital & Medical Research Centre, Mumbai    26 September 2021

Confocal laser endomicroscopy (CLE) is used as a diagnostic aid to detect food allergies or intolerances in patients with irritable bowel syndrome (IBS). It produces real-time high-resolution images of the gastrointestinal tract after intravenous injection of fluorescein during endoscopy. However, according to a recent study, CLE failed to meet the mark in accurately diagnosing wheat sensitivity in patients with non-celiac IBS.1,2

This prospective multicenter study, published in Gut, included 147 outpatients with non-celiac IBS, who met the Rome III criteria. Women constituted over three quarters (77%) of the study population; 41% had IBS with diarrhea (IBS-D), 10% had IBS with constipation (IBS-C), while 49% had mixed IBS (IBS-M). Any alterations in the duodenum were assessed with CLE to detect potential wheat sensitivity after exposure to wheat (3 g; index testing), soy (3 g), yeast (1 g), or milk (1.5 g), each diluted in 30 mL of 0.9% sodium chloride solution.

130 patients completed the study. Of these, 74 patients responded to gluten-free diet (GFD) and were diagnosed as having wheat sensitivity after two months. However, only 38 of these 74 patients could be accurately detected by CLE, with sensitivity of 51.4% (97.5% CI: 38.7% to 63.9%) and specificity of 67.9% (97.5% CI: 52.9% to 79.9%); the sensitivity and specificity were much below the acceptable threshold of 80%. Response to GFD was evident not just in patients who were CLE-positive after wheat challenge but also in many CLE-negative patients.

CLE accurately detected 49 of 59 food-sensitive patients with sensitivity of 83.1% (97.5%CI: 69.9% to 91.3%) at six months follow up, and 55 of 67 patients at one year with sensitivity of 82.1% (97.5% CI: 69.5% to 90.2%). Food sensitivity was also diagnosed in CLE-negative patients at 6 months (10 of 18 patients; 55.6% sensitivity) and 1 year (12 of 19 patients; 63.2% sensitivity), thereby adversely affecting the diagnostic accuracy of CLE for wheat sensitivity.

GFD improved many GI symptoms. All patients regardless of IBS subtype experienced reduction in flatulence and abdominal pain. The stool type (Bristol Stool Scale) improved in IBS-D and IBS-C; decline from six to four was seen in IBS-D patients, while increase from two to three was seen in patients with IBS-C.

Thus, response to GFD was seen in both CLE-positive as well as CLE-negative patients, suggesting unsatisfactory diagnostic accuracy of CLE in detecting wheat sensitivity in patients with IBS. According to the study authors, “the diagnostic accuracy of CLE is too low to recommend widespread use of this invasive procedure”. Dietary changes, in the form of GFD, probably work best in diagnosing wheat sensitivity in IBS patients.

References

  1. Bojarski C, et al. Prospective, double-blind diagnostic multicentre study of confocal laser endomicroscopy for wheat sensitivity in patients with irritable bowel syndrome. Gut. 2021 Sep 20;gutjnl-2021-325181.
  2. Endomicroscopy fails to detect wheat sensitivity in IBS patients. MedPage Today September 24, 2021.

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