Chok 2006.

Methods	Randomised clinical trial.
Participants	Country: China. Number randomly assigned: 40. Postrandomisation dropouts: zero. Revised sample size: 40. Mean age: 47 years. Females: 24 (60%). Inclusion criteria: 1. Symptomatic cholelithiasis with or without complications. 2. Elective outpatient cholecystectomy. 3. ASA I or II. 4. Age < 70 years.
Interventions	Participants were randomly assigned to different pressures of pneumoperitoneum. Group 1: low pressure 7 mm Hg (n = 20). Group 2: standard pressure 12 mm Hg (n = 20).
Outcomes	Outcomes reported were mortality, morbidity, conversion to open cholecystectomy, and operating time.
Notes	Trial authors provided additional information in February 2008 and March 2013.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The random sequence is from random number table (author replies)."
Allocation concealment (selection bias)	Low risk	Quote: "Randomization was performed preoperatively at the pre‐anesthetic clinic by drawing consecutive sealed and numbered envelopes by an independent third party (author replies)."
Blinding (performance bias and detection bias) All outcomes	High risk	Quote: "A preset questionnaire was completed on postoperative days 1 and 3 through telephone by the nursing staff, who were blinded to the randomization results (author replies)." Comment: Assessor blinding of primary outcomes was not performed, and so the blinding is inadequate in this trial.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: No postrandomisation dropouts were reported.
Selective reporting (reporting bias)	Low risk	Comment: Important outcomes such as mortality and morbidity were reported.
For‐profit bias?	Low risk	Quote: "This study was funded by the Tung Wah Group of Hospitals (TWGHs) Research Fund‐Research Project."