Robinson 2004.

Study characteristics
Methods	Design: parallel Duration: 6 weeks Assessment: baseline and post‐intervention Country: USA
Participants	Pain condition: phantom/residual limb pain Population: amputees with chronic phantom limb/residual limb pain Minimum pain intensity: ≥ 2 on 0‐10 scale Inclusion criteria Aged 18‐65 Amputation > 6 months before enrollment, pain for at least 3 months, and average pain rating in the last month of at least 2 on a scale of 0‐10 Exclusion criteria Cardiovascular disease or seizures Total participants randomised: 39 Age in years (mean, SD): 44.9 Gender: 5/20 were female Pain duration in years (mean, SD): NR
Interventions	Placebo (benztropine mesylate 0.5 mg) n = 19 Active placebo Identical appearance Amitriptyline n = 20 TCA Maximum dose: 125 mg/day. Titration: week 1: 10 mg/day, week 2, 25 mg/d; week 3, 50 mg/d; week 4, 75 mg/d; week 5, 100 mg/d; and week 6, 125 mg/day. Dosages were increased by study nurse each week until pain relief or tolerance
Outcomes	Pain Mood Physical function Withdrawal
Missing data methods	ITT but no methods specified
Funding source	Non‐pharmaceutical: supported by the National Institutes of Health, National Institute of Child Health and Human Development, National Institute of Neurological Disorders and Stroke (grant no. 1PO1 HD/NS33988)
Conflicts of interest	"No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organisation with which the author(s) is/are associated."
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation methods not specified
Allocation concealment (selection bias)	Low risk	Provision of medication was done by the Harborview Medical Center Pharmacy Investigational Drug Services. Medication was provided to each participant on a weekly basis by the study nurse or by mail for participants who lived far from the study center. A 7‐day supply of medication was provided to each participant each week in identical gelatin capsules placed in a plastic holder (Mediset), so that study personnel and participants were blind to medication assignment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, identical study medication
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported outcomes from blinded participants
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data methods reported, but low withdrawal Attrition Total: 2/39 (5.1%) Placebo: 0/19 (0.0%) Amitriptyline ≤ 125 mg: 2/20 (10.0%)
Selective reporting (reporting bias)	Unclear risk	Outcomes not registered in protocol and protocol registered retrospectively
Other bias	Low risk	No other sources of bias were identified