Rahimi 2010.

Methods	Study design: randomized controlled trial (2 arms) Study duration: not reported Study setting: hospital, single centre, USA
Participants	Adults undergoing elective craniotomy (n = 50) Inclusion criteria Adults undergoing above surgery Exclusion criteria Pregnant Age < 18 yrs Ventilator dependant > 24 hours Allergy to study medications Emergency surgery Mean age, range (years) 44 (range not reported) Numbers allocated to each arm Group intervention (n = 25) Group control (n = 25) Male gender Group intervention: 13/25 Group control: 10/25
Interventions	Technique and timing Oral tramadol 100 mg twice daily plus narcotic medication as required (oxycodone/acetaminophen 5/325 mg every 4 hours as needed and 1 to 2 mg of IV morphine every 2 hours as needed) versus narcotic medication (as above) only Dosage As above
Outcomes	Primary Pain as measured by the visual analogue score (VAS) Secondary Length of hospital stay Cost
Notes	Funding None Other methodologic issues Lack of details regarding several aspects of study design and methodology including randomization, blinding methods, sample size and timing of outcome measurements
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Reported as randomized but method not reported
Allocation concealment (selection bias)	High risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Reported as blinded but authors did not report who was blinded or how they were blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants were followed up and included in the analysis.
Selective reporting (reporting bias)	Low risk	Outcomes reported as specified
Other bias	High risk	Lack of details regarding several aspects of study design and methodology including randomization, blinding methods, sample size and timing of outcome measurements