Kirch 1987.

Methods	Single‐blind placebo‐controlled randomized trial Cross‐over design
Participants	N = 10 patients ‐ 5 male, 5 female Age 18 to 60 years Typical Raynaud's phenomenon and related connective tissue disorders No dropouts
Interventions	Participants given no drugs other than ketanserin, nifedipine, or placebo Initially received placebo orally during washout period of 4 weeks, then randomly assigned to receive either nifedipine or ketanserin orally for 4 weeks Then, a 2‐week lasting placebo phase interconnected with a cross‐over to the final 4‐week lasting therapy phase Total study duration 14 weeks
Outcomes	Participant diary used to record possible adverse effects and frequency, duration, and severity of attacks Severity assessed on a 3‐point scale Patient treatment rating on a 3‐point scale Laboratory parameters performed including blood cell count, erythrocyte sedimentation rate, and biochemical analysis of renal and hepatic function Skin temperature recordings and videomicroscopy performed, thereby monitoring flowmetry, a standard cold provocation test, and typical morphological changes in skin capillaries
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	Single‐blind study ‐ patients unaware of their treatment arm
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participant diary used to record attack frequency and duration and adverse effects
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up
Selective reporting (reporting bias)	Low risk	None detected
Other bias	Low risk	Washout period of 2 weeks separating cross‐over periods