Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Clinical scores
[30] RCT Crossover design 3-armed trial	16 people	Clinical score and self-evaluation of tremor 5 weeks with primidone with placebo	P <0.05	Effect size not calculated	primidone
[32] RCT Crossover design	22 people	Clinical score (hand tremor) 10 weeks with primidone with placebo	P <0.02	Effect size not calculated	primidone
Self-rating
[32] RCT Crossover design	22 people	Self-evaluation (hand tremor) 10 weeks with primidone with placebo	P <0.01	Effect size not calculated	primidone
Performance tests
[8] RCT Crossover design 4-armed trial	22 people	Observer-rated score based on ability to write, feed, and function socially 4 weeks 5.2 with primidone 7.8 with placebo	Significance of the difference between primidone and placebo not assessed
[32] RCT Crossover design	22 people	Functional tests (hand tremor) 10 weeks with primidone with placebo	P <0.01	Effect size not calculated	primidone