Pandey 2004.

Methods	Randomised clinical trial.
Participants	Country: India. Number randomised: 459. Post‐randomisation drop‐outs: not stated. Revised sample size: 459. Mean age: 42 years. Females: 308 (67.1%). Inclusion criteria: ASA I or II. Aged 18 to 70 years. Elective laparoscopic cholecystectomy. Exclusion criteria: Body weight exceeding 20% of the ideal body weight. Known history of hypersensitivity to any drug. History of drug or alcohol abuse. Uncontrolled concomitant medical diseases. People with history of chronic pain conditions. Impaired kidney or liver function. Cholelithiasis with known common bile duct pathology or indications of cholecystectomy other than cholelithiasis, laparoscopic converted into open cholecystectomy. Administration of analgesics within 48 h of scheduled surgery.
Interventions	Participants were randomly assigned to 1 of 3 groups. Group 1: gabapentin 300 mg orally 2 h before surgery (n = 153). Group 2: tramadol 100 mg orally 2 h before surgery (n = 153). Group 3: placebo 2 h before surgery (n = 153).
Outcomes	Pain.
Notes	Attempts were made to contact authors in August 2013.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Computer generated table of random numbers used".
Allocation concealment (selection bias)	Unclear risk	Comment: This information was not available.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: This information was not available.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "A senior resident, who was not part of the anesthesia team recorded the pain score". Comment: Further details were not available.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: This information was not available.
Selective reporting (reporting bias)	High risk	Comment: Mortality and morbidity were not reported.
For‐profit bias	Unclear risk	Comment: This information was not available.