New and Improved Biomarker Blood Test for Crohn’s Disease?

A recent study (G D’Haens, O Kelly, R Battat et al. Gastroenterol 2020; 158: 515-26,editorial 463) describes the development and validation of a blood test panel to assess Crohn’s disease (CD) endoscopic activity level.  The authors evaluated a blood test which measured 13 proteins in the blood using samples from 278 patients.  Then there were two validation cohorts:

  • 116 biologic-naive CD patients -cohort 1
  • 195 biologic-exposed CD patients -cohort 2

The blood tests were used to develop an endoscopic healing index (EHI) score (0-100). Higher scores indicate greater disease activity.

Key findings:

  • EHI values below 20 identified remission with a sensitivity of 97.1%  and 83.2% in cohorts 1 & 2 respectively; specificity was 69% and 37% respectively.
  • EHI values below 50 points identified patients with highest specificity of 100% and 88% in cohorts 1 and 2 respectively.
  • EHI AUROC (area under the receiver operating characteristic curve) did not differ significantly from that of fecal calprotectin and were higher than measurement of serum CRP (in cohort 1 but not cohort 2).

The editorial notes that the EHI performed much better in younger, biologically-naive patients and that the EHI could potentially be incorporated into a treat-to-target strategy which would potentially entail followup endoscopy in those with EHI >50.

My take: While the stool calprotectin has some logistical barriers in many patients, the EHI is likely a much more expensive test and needs further validation.  For now, the combination of CRP and calprotectin are the best noninvasive biomarkers to assess CD activity.

Briefly noted: Vedolizumab-Induced Pulmonary Toxicity -Case report of a patient with ulcerative colitis who developed interstitial lung disease (Gastroenterol 2020; 158: 478-9).

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