P329 ECCO grant recipient: preliminary results of the HOT-TOPIC trial (Hyperbaric Oxygen Therapy for the Treatment Of Perianal fistulas In Crohn’s disease)

Abstract Background Beneficial effects of hyperbaric oxygen (HBO) therapy for perianal fistulising Crohn’s disease (pCD) have been suggested in previous publications. The HOT-TOPIC study was designed to further investigate its feasibility and therapeutic effect in 20 therapy-refractory patients with pCD. Here we present the preliminary results. Methods 17 patients with pCD refractory to conventional-therapy > 6 months (medical and/or surgical, no patients with deviating stoma) were treated with 40 sessions of HBO therapy (243–253 kPa, 110 min per session throughout 8 weeks). Medical treatment remained stable from screening, seton drain(s) were removed after 30 treatment. Co-primary outcomes were clinical response as measured by the perianal disease activity index (PDAI) and MRI improvement measured by the modified van Assche index. Secondary outcomes were clinical response as assessed by fistula drainage assessment (FDA), biochemical response and patient-reported outcomes. All outcomes were assessed at baseline and 2 months after HBO. Results 17 patients (6 female, median age 34 years, median duration of disease 13 years) were treated. Median PDAI scores decreased from 8 to 4 (p < 0.001) and MRI scores from 9.4 to 7.3 (p = 0.001). Defined as PDAI of 4 or less, 11 out of 17 patients had inactive perianal disease after treatment, with 3 patients also having a predominantly fibrotic tract on MRI. Of the 45 external openings draining at baseline, 22 were clinically closed after treatment (49%, assessed by FDA). Four patients, three with one external opening and one with five openings at baseline, had no remaining openings after treatment. Median C-Reactive Protein and faecal calprotectin levels decreased from 5.0 and 416 to 2.3 and 31 (p = 0.002 and p = 0.003), respectively. Median scores of the inflammatory bowel disease questionnaire (IBDQ) increased from 169 to 185 (p = 0.001) and VAS scores from the Euroqol-5-dimensions questionnaire increased from 65 to 75 (p = 0.07), higher scores reflecting better quality of life. When asked on a validated decision regret scale if patients regretted their decision to undergo HBO, the mean score was 12.5 (0–100, higher scores indicating higher regret). During follow-up, none of the patients needed new (experimental) medication, re-interventions or stoma. Seven out of 17 patients experienced trouble equalising middle ear pressure during HBO, with four patients showing signs of barotrauma after otoscopy. Three patients needed tympanostomy tubes. No other clinically relevant adverse events occurred, and no adverse events led to discontinuation of the treatment. Conclusion Based on preliminary data, HBO treatment is associated with significant improvement in pCD, as measured by clinical and MRI endpoints.