Raue 2011.

Methods	Randomised controlled trial Multi‐centric (12 centres), Germany
Participants	Participants were enrolled between February 2005 and June 2008. A total of 156 participants were randomised: 77 in the LRS group and 79 in the OSR group. Only 75 participants underwent LSR (median age 64, range 27 to 85) vs 68 participants who underwent OSR (median age 68, range 38 to 84). 66% of these participants were female. Inclusion criteria: participants with a proven stage II/III disease (stage II: pericolic inflammation with or without local abscess; stage III: recurrent disease with stenosis, fistula, or bleeding) according to the classification of Stock and Hansen (Hansen 1999) Exclusion criteria: urgent surgery; fistulas to adjunct organs; body mass index > 34 kg/m²; manifest coagulopathy
Interventions	Study interventions:"Left colonic flexure was only mobilized if needed. The distal resection margin was the upper rectum below any visible taenia coli. The proximal resection margin was placed in the non‐inflamed descending colon. The unfixed specimen should measure at least 25 cm. Anastomosis was created using a circular stapler or a biofragmentable ring. OSR was performed via a midline or a traverse laparotomy. LSR was performed in a 4–5 trocar technique. The specimen was removed via a suprapubic or a left‐sided traverse incision. If conversion was necessary, LSR was converted to OSR."
Outcomes	Primary outcome Global health status after surgery ("assessed with the EORTC‐QLQ‐C30 v3 questionnaire 30 days after surgery") Secondary outcomes Postoperative mortality ("from whatever course within 12 months after operation") Postoperative complications ("Anastomotic leakage, intra‐abdominal/pelvic abscess, postoperative bleeding, and other reasons for reoperation were classified as major complications. Wound infection, deep vein thrombosis, urinary tract infection, and delayed bowel motility without the need for reoperation were classified as minor complications.") Postoperative pain scores ("assessed within the first 8 days after operation using a visual analogue scale") Operating time ("calculated from skin incision to application of wound dressings") Conversion rate ("defined as any unplanned laparotomy") Specimen length ("determined after fixation")
Funding sources. Any declaration of interest	This trial was supported by the Charité–University Medicine Berlin. No funding was received from other organisations.
Trial registry entries	The trial was registered with ISRTCN: Identification number 55776829.
Notes	Recurrent severe violations of the protocol were discovered at only 1 participating centre during recruitment and analysis (defiance of the randomisation result). All patients from this hospital (6 randomised patients and 17 patients operated on according to their preferred technique) were excluded from further analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The random sequence generation was not clearly reported. "The randomisation was performed using the method of minimisation and stratifying for participating clinic, operating surgeon, sex, age (< 50, 50 to 75, and > 75 years), body mass index (< 26 and ≥ 26 kg/m2), and stage of disease (stage II, stage III)."
Allocation concealment (selection bias)	Unclear risk	The method of allocation concealment was not clearly reported. Allocation of participants was performed centrally by telephone calls (as reported by the corresponding author).
Blinding of participants and personnel (performance bias) All outcomes	High risk	Given the type of intervention provided, it was not possible to blind investigators.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information was provided.
Incomplete outcome data (attrition bias) All outcomes	High risk	Two participants in the laparoscopic group and 11 in the open group did not receive the allocated treatment, and study authors did not clearly state the reasons. After treatment, 2 participants in the laparoscopic group and 4 in the open group were excluded from the analysis, but the reasons for this are not stated by investigators. Finally, 2 participants in the open group were lost (died) to follow‐up and were not analysed for the outcomes of interest. According to the intention‐to‐treat principle, converted cases were analysed in the laparoscopic group.
Selective reporting (reporting bias)	Low risk	The study protocol is available, and all of the study's prespecified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified way (Schwenk 2004).