Hawkins 1985.

Methods	Randomized controlled trial Double‐blinding not explicitly stated but given benefit of the doubt
Participants	71 entering the study and 57 completing the study ‐ 49 female, 8 male At least 2 attacks during last 2 weeks before enrollment Mean age 49 years, range 17 to 78 Mean duration of Raynaud's 14.7 years, range 1 to 52 20 with idiopathic Raynaud's 25 with systemic sclerosis 4 with seropositive rheumatoid arthritis 3 with mixed connective tissue disease 3 with systemic lupus erythematosus 1 with Sjogren's syndrome and seropositive polyarthritis
Interventions	Following 2‐week run‐in period without therapy Randomized to either 10 mg nifedipine 4×/d or placebo Underwent 4 consecutive periods of treatment with alternating nifedipine and placebo
Outcomes	Number of attacks per week Severity on a 10‐cm visual analogue scale and on a 5‐point scale (none, mild, moderate, severe, and very severe) BP, presence of digital ulcers Thermal stress test
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	Unclear risk	Does not explicitly state double‐blinding
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Subjective participant assessments of number and severity of attacks
Incomplete outcome data (attrition bias) All outcomes	High risk	14/71 dropouts ‐ 6 due to intercurrent illness, 8 due to drug side effects (7 from nifedipine and 1 from placebo)
Selective reporting (reporting bias)	Unclear risk	Severity of attacks not reported on a 5‐point Likert scale as proposed
Other bias	Unclear risk	No mention of washout period between cross‐over phases