Olsen 1987.

Methods	Randomized controlled trial
Participants	Patients with chronic anal fissure
Interventions	Anal stretch (10) versus lateral subcutaneous internal sphincterotomy (10)
Outcomes	Persistence of the fissure and incontinence to flatus Anal stretch persistence risk = 0.30; incontinence risk = 0.20 Sphincterotomy persistence risk = 0.10; incontinence risk = 0.20
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	inadequate
Blinding of outcome assessment (detection bias) All outcomes	High risk	inadequate
Drop‐outs All outcomes	Low risk	zero