Efficacy of amoxicillin/clavulanic acid after surgical drainage of perianal abscess in the prevention of the development of anal fistula (PERIQxA study): study protocol for a multicenter randomized, double-blind clinical trial.

BACKGROUND: Anorectal fistula, which is a relatively common pathology, is the chronic manifestation of the acute perirectal process that forms an anal abscess. The development of a fistula after incision and drainage of an anal abscess is seen in approximately 26-37%. Its treatment is a relevant topic, and the role of the use of antibiotic therapy in its prevention remains controversial, after the publication of several studies with contradictory results and several methodological limitations. Our hypothesis is that the combination of amoxicillin and clavulanic acid will reduce the incidence of anal fistula.

METHOD: The aim of this study is to evaluate the efficacy of antibiotherapy after surgical drainage of perianal abscess in the development of perianal fistula. The PERIQxA study is a multicenter, randomized, double-blind controlled trial. The study has been designed to include 286 adult patients who will be randomly (1:1) assigned to either the experimental (amoxicillin/clavulanic acid 875/125 mg TDS for 7 days) or the control arm (placebo). The primary outcome measure is the percentage of patients that develop perianal fistula after surgery and during follow-up (6 months).

DISCUSSION: This clinical trial is designed to evaluate the efficacy and safety of amoxicillin/clavulanic in the prevention of perianal fistula. The results of this study are expected to contribute to stablish the potential role of antibiotherapy in the therapeutics for anal abscess.

TRIAL REGISTRATION: EudraCT Number: 2021-003376-14. Registered on November 26, 2021.