Jänes 2009.

Methods	Randomised trial. Envelope randomisation
Participants	54 (mean age control group = 71 (67 to 76 years), invervention group = 70 (64 to 75 years)), Male 31:23 Female
Interventions	Participants received either a traditional end colostomy (n = 21) or had a Vypro mesh placed dorsal to the rectus abdominis muscle and anterior to the posterior rectal sheath (n = 15).
Outcomes	Development of parastomal hernia at 5 years from index surgery by clinical examination
Length of Follow Up	Mean 65.2 months (range 57 to 83 months)
Notes	Mortality data from Jänes 2009 were only available for a 12‐month follow‐up (Jänes 2004a), therefore subsequent data may not be relevant in the assessment of this review. 6 participants from the control group and 12 from the intervention group lost to follow‐up.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Comment: Participants were randomised using consecutively numbered, sealed envelopes. No random sequence generation
Allocation concealment (selection bias)	Low risk	Quote: "consecutively numbered sealed envelopes" Comment: Probably occurred
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: Not possible to blind the surgeon as to which procedure was being performed
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Patients were examined after 1 month, 12 months, and 5 years by an investigator blinded to the actual randomisation. They were then examined straining in both an erect and a supine position." Comment: Blinded outcome assessment
Incomplete outcome data (attrition bias) All outcomes	Low risk	Those lost to follow‐up were accounted for.
Selective reporting (reporting bias)	Low risk	We identified no selective reporting.
Early Stopping	Low risk	Comment: Sample size calculation was included. Trial was stopped early on ethical grounds due to statistical testing favouring the mesh.