Different effects of anti-TNF-alpha biologic drugs on the small bowel macroscopic inflammation in patients with ankylosing spondylitis.

Background & Aims: Considering the ability of anti-TNF alpha drugs to lower the burden intestinal inflammation in patients with inflammatory bowel disease (IBD), and the similarity between IBD and ankylosing spondylitis (AS) regarding inflammatory intestinal involvement, we aimed to investigate the impact of anti-TNF alpha biologic therapy on subclinical intestinal inflammation in AS patients.

Methods: Between January 2008 and December 2013, 38 AS patients and 23 controls were enrolled in the study and investigated with small bowel videocapsule endoscopy examination and ileocolonoscopy. Each tertile of the small bowel (proximal, mid and distal) was assessed by calculating the Lewis score based on the image stream.

Results: The Lewis scores were significantly higher in the AS group compared to controls (580.9 ± 818 vs. 81 ± 121, p<0.001). 16 patients (42.1%) were on anti-TNF alpha therapy (Adalimumab (n = 5), Infliximab (n = 5) or Etanercept (n = 6)).31.3% of them used NSAIDs simultaneously, compared with 77.3% of the other patients (p<0.01). Their Lewis scores were lower compared to the other patients for the entire small bowel (306 ± 164 vs. 790 ± 1038, p = 0.015), its proximal and distal tertiles (238 ± 154 vs. 560 ± 543, p = 0.021, and 140 ± 189 vs. 300 ± 220, p = 0.027, respectively). The Lewis score was also lower in patients receiving Adalimumab/Infliximab compared to those on Etanercept for the entire bowel and its distal tertile (262 ± 165 vs. 380 ± 148, p = 0.069 and 62 ± 101 vs. 273 ± 236, p = 0.060, respectively).

Conclusion: Anti-TNF alpha therapy in patients with AS reduces the subclinical intestinal inflammation, but the magnitude seems to depend upon the class anti-TNF alpha agent used (Clinical Trials. gov NCT00768950).