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Optimal Dosing of Botulinum Toxin for Treatment of Chronic Anal Fissure: A Systematic Review and Meta-Analysis

Lin, Jin Xin M.B.Ch.B.; Krishna, Sanjeev M.B.Ch.B.; Su’a, Bruce M.B.Ch.B.; Hill, Andrew G. M.B.Ch.B., M.D.(Thesis), Ed.D., F.R.A.C.S.

doi: 10.1097/DCR.0000000000000612
Current Status

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.

1 Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand

2 Department of Surgery, The University of Auckland, Auckland, New Zealand

Financial Disclosures: None reported.

Presented at the meeting of the Royal Australasian College of Surgeons’ Surgical Research Society, Sydney, NSW, Australia, November 12-13, 2015.

Correspondence: Jin Xin Lin, M.B.Ch.B., Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1010, New Zealand. E-mail:

© 2016 The American Society of Colon and Rectal Surgeons