Optimal dosing of treatment of chronic anal fissure: A systematic review and meta-analysis

Abstract

BACKGROUND: Chronic anal fissures are associated with significant morbidity and reduced quality of life. Studies have investigated the efficacy of botulinum toxin with variable results; thus, there is currently no consensus on botulinum toxin dose or injection sites. OBJECTIVE: This study aimed to systematically analyze trials studying the efficacy of botulinum toxin for treatment of chronic anal fissure to identify an optimum dosage and injection regimen. DATA SOURCES: A comprehensive review of the literature was conducted according to PRISMA guidelines. PubMed/Medline, Embase, Scopus, and the Cochrane Library were searched from inception to June 2015. STUDY SELECTION: All clinical trials that investigated the efficacy of botulinum toxin for chronic anal fissure were selected according to specific criteria. INTERVENSIONS: The interventions used were various doses of botulinum toxin. OUTCOME MEASURES: Clinical outcomes, dosage, and injection site data were evaluated with weighted pooled results for each dosage and 95% confidence intervals. RESULTS: There were 1158 patients, with 661 in botulinum toxin treatment arms, from 18 clinical trials included in this review. The outcomes of interest were 3-month healing, incontinence, and recurrence rates. Meta-regression analysis demonstrated a small decrease in healing rate (0.34%; 95% CI, 0–0.68; p = 0.048) with each increase in dosage, a small increase in incontinence rate (1.02 times; 95% CI, 1.0002–1.049; p = 0.048) with each increase in dosage and a small increase in recurrence rate (1.037 times; 95% CI, 1.018–1.057; p = 0.0002) with each increase in dosage. The optimum injection site could not be determined. LIMITATIONS: This study was limited by weaknesses in the underlying evidence, such as variable quality, short follow-up, and a limited range of doses represented. CONCLUSIONS: Fissure healing with lower doses of botulinum toxin is as effective as with high doses. Lower doses also reduce the risk of incontinence and recurrence in the long term.