Induction of mucosal healing by biologics is topographically comparable in proximal and distal small bowel Crohn's disease.

BACKGROUND AND AIMS: Proximal small bowel (SB) involvement is associated with worse outcomes in Crohn's disease (CD). We aimed to compare biologic response between proximal and distal SB segments using video capsule endoscopy (VCE) to assess small intestinal topography of inflammation.

METHODS

Pooled analysis of three prospective cohorts including patients initiating or undergoing optimization of biologic therapy, who were evaluated with SB-VCE at baseline, end-of-induction (14-26 weeks), and 1-year. Mucosal inflammation was defined as Lewis score (LS)≥135. The first two SB tertiles were classified as proximal SB and the third as distal SB. Proximal inflammation was defined by involvement of either of the two proximal tertiles. Generalized estimating equations accounted for within-patient correlation, adjusting for segment, timepoint, biologic class, and disease phenotype.

RESULTS

Ninety-nine patients received biologics (53-anti-TNF, 43-vedolizumab, 3-ustekinumab). 82 completed end-of-induction and 59 completed 1-year assessments. The rate of proximal SB inflammation decreased from 63% at baseline to 44% at the end-of-induction (p=0.001) and 41% at 1-year (p=0.003), while distal inflammation declined from 95% to 78% (p=0.001) and 71% (p<0.001), respectively. There was comparable degree of mucosal healing between proximal and distal segments at the end-of-induction (RD 7%, 95% CI -9% to 22%, p=0.391) and 1-year (RD 0%, 95% CI -17% to 17%, p=1.000). Using a higher inflammatory threshold (LS≥350), mucosal inflammation significantly decreased in both proximal (baseline: 38%, vs. end-of-induction: 16% [p<0.01] and 1-year: 19% [p=0.02]) and distal SB segments (baseline: 76% vs end-of-induction: 35% [p<0.01] and 1-year: 19% [p<0.01]).

CONCLUSION

Biologic therapy is associated with topographically comparable improvement in mucosal inflammation across proximal and distal SB segments.