Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Fissure healing, persistence, or recurrence
Systematic review	365 people with chronic anal fissure 5 RCTs in this analysis	Non-healing of anal fissure 18 weeks–3 years 19/177 (11%) with lateral internal sphincterotomy 77/188 (41%) with botulinum toxin	OR 7.20 95% CI 3.97 to 13.07 P <0.00001	Large effect size	lateral internal sphincterotomy
RCT 4-armed trial	160 people with chronic anal fissure	Recurrence up to 5 years 4/40 (10%) with open lateral internal sphincterotomy 21/40 (53%) with botulinum toxin	Not reported
RCT	40 people with chronic anal fissure	Persistence or recurrence 3 years 0/20 (0%) with lateral internal sphincterotomy 7/20 (35%) with botulinum toxin	P = 0.008	Effect size not calculated	lateral internal sphincterotomy
RCT	50 people with chronic anal fissure	Complete healing of fissure 12 months 23/25 (92%) with lateral internal sphincterotomy 12/25 (48%) with botulinum toxin	P = 0.001	Effect size not calculated	lateral internal sphincterotomy