Kallenberg 1987.

Methods	Double‐blind randomized cross‐over trial
Participants	16 patients 8 with primary Raynaud's ‐ 6 female and 2 male Mean age 34 years, range 25 to 47 Duration of disease 20 years, range 3 to 37 8 with secondary Raynaud's ‐ 5 female and 3 male Mean age 44 years, range 28 to 63 Duration of disease 17 years, range 9 to 24
Interventions	Nifedipine or placebo
Outcomes	Side effects
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Evidence insufficient for judgement of risk
Allocation concealment (selection bias)	Unclear risk	Evidence insufficient for judgement of risk
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind study
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participant diary used to record subjective assessments
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 1/16 dropouts
Selective reporting (reporting bias)	Unclear risk	None detected
Other bias	Unclear risk	Evidence insufficient for judgement of risk