Sigma Trial 2009.

Methods	Randomised controlled trial Multi‐centric (5 centres), Netherlands
Participants	Participants were enrolled between February 2002 and December 2006. A total of 104 participants were randomised: 52 participants underwent LSR (median age 62, range 32 to 85) and 52 participants underwent OSR (median age 63, range 30 to 84). 57% of participants were female. Inclusion criteria:"Symptomatic diverticulitis of the sigmoid colon: previous 2 or more recurrent attacks of acute diverticulitis with (Hinchey I) or without pericolic abscess necessitating hospitalization with intravenous antibiotics and nil per os; previous recurrent attacks of acute diverticulitis with percutaneously drainable distant abscess necessitating CT‐guided drainage (Hinchey IIa); presence of internal fistula between the sigmoid colon and a hollow organ with abscess (Hinchey IIb) or without; presence of symptomatic stricture of the sigmoid colon with no evidence of cancer; recurrent severe diverticular bleeding requiring blood transfusions verified at colonoscopy and/or arteriogram. Surgery was performed at least 3 months after the last attack of diverticulitis." Exclusion criteria:"failure to sign informed consent, previous colorectal resectional surgery, previous laparotomy other than for gynaecologic or obstetrical surgery, and perforated diverticulitis with peritonitis (Hinchey III or IV)"
Interventions	Laparoscopic sigmoid colectomy:"LSR was performed through 4 or 5 ports. The splenic flexure was mobilized if needed. The sigmoid colon was mobilized. The left ureter was identified. The sigmoid vessels were divided. The rectosigmoid junction was identified by the ab sence of taenia coli and transected at the level of the promontory using a laparoscopic stapler. The oral end of the transacted bowel was exteriorized through a suprapubic incision. The proximal resection margin was placed on supple, normal appearing descending colon with no signs of inflammation or induration of the mesentery and serosal surface. The specimen was retrieved and a purse string suture was fashioned at the oral bowel end. An intracorporeal double‐stapled anastomosis was created after closure of the suprapubic wound and reestablishment of the pneumoperitoneum. Care was taken to achieve a truly tension‐free anastomosis. If conversion was necessary, LSR was converted to a hand‐assisted LSR or to OSR. The hand‐port device was placed at the suprapubic incision site. The left hand of the surgeon was introduced through the hand‐port and assisted in improving exposure of the surgical field. All wounds were closed layer by layer." Open sigmoid colectomy:"OSR was carried out through a midline laparotomy. The splenic flexure was mobilized if needed. The sigmoid colon was mobilized. The left ureter was identified. The sigmoid vessels were divided. The rectosigmoid junction was identified by the absence of taenia coli and transected at the level of the promontory with a stapler. The proximal resection margin was placed on supple, normal appearing descending colon with no signs of inflammation or induration of the mesentery and serosal surface. The specimen was retrieved and a purse string suture was fashioned at the oral bowel end. A double‐stapled anastomosis was performed. Care was taken to achieve a truly tension‐free anastomosis. The midline wound was closed layer by layer."
Outcomes	Primary outcomes Short‐term (30 postoperative days) mortality (defined as "death from whatever cause occurring within 30 days from surgery in hospital or after discharge") Short‐term (30 postoperative days) complications ("classified as minor and major, the latter including reoperations within 30 days from surgery. Deep venous thrombosis, pneumonia, urinary tract infection, and wound infection were recorded as minor complications. Anastomotic leakage, intra‐abdominal abscess, severe postoperative bleeding with requirement for blood transfusion, and reoperations were classified as major complications") 6‐Month postoperative mortality ("defined as death due to whatever cause occurring from 30 days to 6 months postoperatively") Late complications ("occurring from 30 days to 6 months postoperatively including incisional hernias, small bowel obstruction, recurrent episodes of diverticulitis, fistula, anastomotic strictures, abscesses, and reoperations") Total direct costs for the period of 30 days after surgery Total direct costs for the 6‐month follow‐up period (only total healthcare costs) Secondary outcomes Operating time (minutes) ("calculated from the first skin incision to the application of dressings") Estimated blood loss (mL) ("recorded by the anaesthesiologist") Mobilisation of the splenic flexure Conversion rate ("defined as unplanned laparotomy or conversion to hand‐assisted LSR") Specimen length (cm) ("measured by the pathologist after fixation") Hospital stay (days) ("determined by independent physicians blind to the allocation sequence") Need for oral and systemic analgesia (days) Visual analogue scale (VAS) pain score ("measured preoperatively and daily after surgery up to postoperative day 4") Quality of life assessment (evaluated "by the Short Form‐36 (SF‐36) questionnaire measured preoperatively 6 weeks and 6 months after surgery") Resumption of diet (days) Quality of life assessment (evaluated "by the Short Form‐36 (SF‐36) questionnaire measured preoperatively and 6 weeks after surgery") Restoration of bowel continuity after stoma formation
Funding sources. Any declaration of interest	Not reported
Trial registry entries	The trial was registered in Current Controlled Trials (ISRCTN 43911188) and Nederlands Trial Register (NTR 928); the protocol was published in BMC Surgery (Klarenbeek 2007).
Notes	Economic outcome assessment, postoperative pain score, and postoperative general health status were performed in only 57 patients recruited at the Department of Surgery of VU University Medical Center, Amsterdam.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation process. Participating institutions enrolled eligible participants by logging on to a secure website that provided an automated assignment and randomisation number for each participant (www.sigmatrial.nl).
Allocation concealment (selection bias)	Low risk	Allocation concealment was ensured by assigning identity numbers to enrolled participants and by separating the generator of the allocation from the executor.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Given the type of intervention provided, it was not possible to blind investigators. However, investigators attempted to blind participants: "Participants and hospital staff, including physicians in charge of participant discharge, were blinded. Blinding was provided by the of use identical opaque dressings covering the entire abdomen."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not clearly stated in the manuscript whether outcome assessors were or were not blinded to treatments
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 1 participant did not complete follow‐up because of death from myocardial infarction. According to the intention‐to‐treat principle, converted cases were analysed in the laparoscopic group.
Selective reporting (reporting bias)	Unclear 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 (Klarenbeek 2007). However, results for postoperative pain were not adequately reported: Study authors reported differences (daily on average VAS 1.6 point less) without reporting mean values for both groups at baseline and post baseline, without providing the point in time at which the post‐baseline value was estimated.

BMI: body mass index.

CT: computed tomography.

LSR: laparoscopic surgical resection.

OSR: open surgical resection.

RCT: randomised controlled trial.

VAS: visual analogue scale.