Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Frequency of attack
Systematic review	59 people with Raynaud's phenomenon secondary to systemic sclerosis 6 RCTs in this analysis	Mean reduction in frequency of attack 2 weeks with calcium channel blockers with placebo Absolute results not reported	WMD –8.31 attacks 95% CI –15.71 attacks to –0.91 attacks P = 0.03 Methodological limitations; see further information on studies for full details	Effect size not calculated	calcium channel blockers
Systematic review	44 people with Raynaud's phenomenon secondary to systemic sclerosis 5 RCTs in this analysis	Mean reduction in frequency of attack 2 to 12 weeks with nifedipine (10–20 mg three times daily) with placebo	WMD –10.21 attacks 95% CI –20.09 attacks to –0.34 attacks P = 0.04 Methodological limitations; see further information on studies for full details	Effect size not calculated	nifedipine
Severity of attack
Systematic review	31 people with Raynaud's phenomenon secondary to systemic sclerosis 3 RCTs in this analysis	Severity of attack 2 weeks with calcium channel blockers with placebo	SMD –0.69 95% CI –1.21 to –0.17 P = 0.01 Methodological limitations; see further information on studies for full details	Effect size not calculated	calcium channel blockers