Efficacy of botulinum toxin type A administration within the current therapeutic algorithm for chronic anal fissure: study protocol for the prospective multicentre observational study FISURBOT-GECO6

Abstract Background Chronic anal fissure is a common, benign anorectal condition associated with impaired quality of life. Despite the availability of several therapeutic options, considerable variability persists in its management, particularly regarding the role of botulinum toxin type A administration within the current treatment algorithms. Although botulinum toxin type A injection is a widely used approach to achieve chemical sphincterotomy, its real-world efficacy and safety across different clinical scenarios remain insufficiently characterised. Aim Our objective is to evaluate the efficacy and safety of botulinum toxin type A injection for the treatment of chronic anal fissure after failure of topical therapy or lateral internal sphincterotomy in routine clinical practice settings by analysing the healing rate, continence outcomes and the need for subsequent surgical intervention in predefined clinical scenarios. Methods FISURBOT-GECO6 (0143–2024-OBS) is a national, multicentre, prospective, pragmatic observational study. Consecutive patients with chronic anal fissure in whom botulinum toxin treatment is recommended according to routine clinical practice are eligible. Patients will be classified into three clinical scenarios: (1) chronic anal fissure with sphincter hypertonia and no risk factors for anal incontinence after failure of topical therapy; (2) chronic anal fissure with recognised risk factors for anal incontinence after failure of topical therapy; and (3) chronic anal fissure persisting or recurring at least 12 weeks after lateral internal sphincterotomy. Botulinum toxin type A administered at a dose of 50 or 100 IU, according to routine practice. Patients will be evaluated at 1, 3 and 12 months after treatment. The primary outcome is clinical healing. Secondary outcomes are anal continence, procedure-related morbidity, need for repeat treatment or surgery and patient satisfaction. Expected relevance This study will provide prospective, real-world data on the efficacy and safety of botulinum toxin type A injection for chronic anal fissure management in clinically relevant scenarios. The results are expected to help clarify the role of this approach within current therapeutic algorithms and inform clinical decision-making in daily practice. Trial Sponsor Spanish Society of Coloproctology (AECP).