Muller‐Buhl 1983.

Methods	Randomized double‐blind placebo‐controlled trial Parallel design
Participants	N = 24 patients ‐ 10 women, 14 men 3 with collagen disease, 21 with primary Raynaud's phenomenon Mean age 43.5 for drug, 43 for placebo No dropouts
Interventions	Treatment with calcium antagonist Bay K 9320 or placebo lasting 3 weeks
Outcomes	Effectiveness, severity, and frequency recorded Subjective improvement
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information provided for judgement of risk
Allocation concealment (selection bias)	Unclear risk	No information provided for judgement of risk
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information provided for judgement of risk
Selective reporting (reporting bias)	Unclear risk	No information provided for judgement of risk
Other bias	Unclear risk	No information provided for judgement of risk