Effectiveness of a high fiber diet in improving constipation in patients with defecatory dyssynergy under treatment with anorrectal biofeedback. Exploratory, randomized clinical trial.

Introduction: Fiber is the initial treatment in chronic functional constipation. However, its role in the group of patients with defecatory dyssynergy is not well established. The objective of the study is to evaluate the efficacy and safety of a high fiber diet in patients with defecatory dyssynergy in the treatment with anorectal biofeedback.

Patients And Methods: An exploratory, randomized (1:1), double-blind, controlled «add-on» clinical trial was carried out in a reference center in Spain in patients with functional constipation and defecatory dyssynergy according to the ROMEIV criteria.

Control Group: treatment with biofeedback and low-fiber diet (15-20g/day). Experimental group: treatment with biofeedback and high fiber diet (25-30g/day). Analyzed: responder (primary endpoint), patient whose defecatory dyssynergy had been corrected (>20% reduction in anal pressure during the defecation maneuver and normal balloon expulsion test); anorectal parameters (anal relaxation, reduced straining); safety (abdominal symptoms: flatulence, pain, borborygmus, bloating).

Results: A total of 44 patients were randomized: 22 per group. The percentage of responders was 75% (15/20; 95%CI: 53 89%) control group and 70% (14/20; 95%CI: 48-85%) experimental group, P=.225. Differences in favor of the control group were only observed in abdominal symptoms: flatulence (P=.028), abdominal distension (P=.041) and digestive comfort (P=.043).

Conclusions: In patients with defecatory dyssynergy, a high-fiber diet not only does not improve the efficacy of anorectal biofeedback but is associated with a loss of improvement in abdominal symptoms.