Fecal immunochemical test accurately predicts healing in ulcerative colitis

Last Updated: 2017-07-20

By Will Boggs MD

NEW YORK (Reuters Health) - The noninvasive fecal immunochemical test accurately predicts mucosal healing in patients with ulcerative colitis, researchers from China report.

"Fecal immunochemical test (FIT) can accurately predict mucosal healing not only on the endoscopic level, but also on the histological level in UC," Dr. Siew C. Ng from The Chinese University of Hong Kong told Reuters Health by email. "Its performance is comparable to fecal calprotectin (FC), which is up to now known as the most accurate noninvasive marker for assessing disease activity in ulcerative colitis (UC)."

Some earlier studies addressed the usefulness of FIT in assessing endoscopic healing in UC, but its accuracy to assess histological healing has not been determined.

Dr. Ng and colleagues compared the accuracy of FIT with that of FC for predicting histological healing in their prospective study of 140 patients with UC.

Among these patients, 71% were in clinical remission (although 16% of these had endoscopic inflammation), and up to 30% of those with endoscopic healing had histological inflammation.

FIT results correlated significantly with colonoscopic findings and with the Geboes score and the Nancy index, two widely used histologic indices.

By ROC analysis, the predictive accuracy for endoscopic healing was similar for FIT (AUC=0.772) and for FC (AUC=0.793, p=0.773), the researchers report in the Journal of Crohn's and Colitis, online July 13.

FIT and FC also showed similar accuracy in predicting histological healing using either the Geboes score or the Nancy index.

For predicting endoscopic healing, FIT at a cutoff of 50 ng/mL had 72% sensitivity, 68% specificity and 82% positive predictive value, compared with 81% sensitivity, 71% specificity, and 87% positive predictive value for FC.

Results were also similar for both methods for predicting histological healing.

The combination of FIT and FC improved the accuracy of predicting histological healing, and more than 85% of patients with FIT <50 ng/mL and FC <50 mcg/g achieved histological healing.

Colonoscopy had a higher sensitivity and negative predictive value, but lower specificity and positive predictive value for histological healing, compared with FIT and FC, and the overall accuracy of both fecal markers and colonoscopy for predicting histological healing was comparable.

"FIT combined with FC resulted in a higher specificity for the prediction of histological healing, and colonoscopy with multiple biopsies could be avoided in over 85% of UC patients with low levels of both markers," Dr. Ng said.

"If our results are validated in an independent cohort with a larger sample size, I would prefer FIT for disease monitoring in UC," she said. "Given its advantage of being much cheaper and user-friendly, it is suitable to be repeatedly tested at clinic. FC can be used intermittently (e.g., at 3-6-month interval) for predicting histological healing, and colonoscopy can be saved mainly for surveillance."

In a related report in the journal, Dr. Azucena Salas from CIBER-EHD, in Barcelona, Spain, and colleagues describe the usefulness of transcriptional blood biomarkers as noninvasive surrogate markers of mucosal healing and endoscopic response in ulcerative colitis.

Their microarray analysis identified 122 genes significantly altered in endoscopically active UC, and the expression of four genes - HP, CD177, GPR84, and S100A12 - correlated with the degree of endoscopic activity.

Moreover, alteration in the expression of these four genes correlated significantly with changes in endoscopic activity following treatment with anti-TNF compounds.

Dr. Salas told Reuters Health by email, "In my opinion, the most interesting aspect of the investigation is that the identified biomarkers appear to reflect individual changes in patients in response to therapy, suggesting that they could be useful for monitoring, in a non-invasive manner, improvements in the mucosal lesions."

"I think it is also important that clinicians understand the limitations of these and other blood biomarkers used to monitor disease in IBD patients," she cautioned. "Their main weakness is their low sensitivity, as they are not able to detect endoscopic disease activity in all patients at all times. This is true of all known blood biomarkers to varying degrees, and though transcriptional biomarkers present slightly better sensitivity, the differences are not dramatic."

"Despite this," Dr. Salas concluded, "blood transcriptional biomarkers may assist clinicians' decisions when dealing with situations in which performing another endoscopic examination may not be an option. In such cases, changes in biomarker expression patterns from baseline can help monitor therapeutic responses."

SOURCE: http://bit.ly/2udRyn0 and http://bit.ly/2vmgjw8

J Crohns Colitis 2017.