Zesiewicz 2007a.

Study characteristics
Methods	Double‐blind, placebo controlled, parallel study
Participants	22 patients randomised (11 to pregabalin, 11 to placebo) Mean age 57 years (SD 13) Male 40% Baseline TRS 39 (SD 20)
Interventions	Group 1: pregabalin 50 mg‐600 mg (titration 75 mg every 4 days) Group 2: placebo Follow‐up: 42 days
Outcomes	TRS total score (0 to 100) and subscales: severity (16 points), motor tasks (36 points) and functional disability (32 points), CGI (seven‐point scale)
Notes	Trial setting: out‐patients (Parkinson’s Disease and Movement Disorders Center) Country: University of South Florida, Tampa, Florida, USA
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Computer generated randomization schedule"
Allocation concealment (selection bias)	Unclear risk	Not specified
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"PGB and placebo were supplied in identical containers"; "both patients and raters were blind to randomization"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"Tremor measurements were conducted by a blinded rater"
Incomplete outcome data (attrition bias) All outcomes	High risk	"Last observation carried forward was used for analysis for patients who prematurely withdrew the study"
Selective reporting (reporting bias)	Low risk	Free
Other bias	Low risk	Free

CGI: clinical global impression;PGB: pregabalin; RCT: randomised controlled trial; TRS: Fahn‐Tolosa‐Marin Tremor Rating Scale.