Challenor 1987.

Methods	Randomized placebo‐controlled double‐blind trial 3‐Way cross‐over design
Participants	36 participants with primary Raynaud's (32 female, 4 male) Mean age 47 years (range 19 to 67) Mean Raynaud's phenomenon duration 26.2 years (range 2 to 60 years) Vasoactive drugs discontinued before entry and other concomitant drug discontinued in 19 patients
Interventions	Nisoldipine 5 mg, 10 mg daily or matching placebo before food 3‐Way cross‐over each with duration of 4 weeks Total study length 3 months
Outcomes	Daily Raynaud's phenomenon attacks Severity Number of times outdoors Subjective response to treatment on 1 to 5 scale (1 = much better, 2 = better, 3 = same, 4 = worse, 5 = much worse) and 10‐cm visual analogue scale (from 0 = much better to 10 = much worse)
Notes	Length of washover not clear Mean ambient temperature similar during all treatment periods
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 number of attacks, severity, subjective improvement
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	4/36 dropouts
Selective reporting (reporting bias)	Low risk	None detected
Other bias	Unclear risk	Length of washover not clear