Mowafi 2008

Methods	Randomized, double‐blind, placebo‐controlled study Location: Saudi Arabia Study design: parallel, 2‐armed
Participants	A total of 40 patients randomized 40 patients completed: 20 in melatonin group, 20 in placebo group Age: melatonin 44.6 ± 11.4, placebo 42.8 ± 12.1 Gender (M/F) in %: melatonin (60/40), placebo (50/50) ASA class: I‐II Type of surgery: hand surgery Type of anaesthesia: regional Baseline (anxiety, pain) described: yes, yes
Interventions	Melatonin: 10 mg Placebo Administration route: oral Time of administration: 90 min preoperatively
Outcomes	1. Tourniquet‐related pain by Verbal Pain Score (0 to 10) 2. Analgesic consumption by fentanyl requirements and diclofenac consumption 3. Anxiety assessed by Verbal Anxiety Score (0 to 10) (preoperative) 4. Haemodynamics by mean arterial pressure and heart rate 5. Onset and recovery of sensory and motor blockade (minutes)
Notes	Sample size calculation: described Author contacted by e‐mail on 9 August 2013 to clarify unspecified issues: no answer
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Patients were randomly allocated using an online research randomizer..." (page 1422) (Mowafi 2008)
Allocation concealment (selection bias)	Low risk	Quote:"Patients were randomly allocated using an online research randomizer..." (page 1422)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No reported dropouts or missing data
Selective reporting (reporting bias)	Unclear risk	Study protocol not available
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding of patients, surgeons or personnel not described
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "All the evaluations were performed by a blinded observer" (page 1423)