of findings for the main comparison. Calcium channel blockers for primary Raynauds's phenomenon Calcium channel blockers for primary Raynauds's phenomenon Patient or population: primary Raynaud's phenomenon Setting: hospital and hospital outpatient clinics Intervention: calcium channel blockers Comparison: placebo Anticipated absolute effects * (95% CI) Outcomes Risk with placebo Risk with Calcium channel blockers Relative effect (95% CI) CI: Confidence interval; RR: Risk ratio; OR: Odds ratio; GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Cochrane Library Trusted evidence. Informed decisions. Better health.