The quality of evidence is downgraded by study limitations (unclear allocation concealment).
A Cochrane review [Abstract] 1 included 7 studies with a total of 296 subjects. Four studies examined nifedipine and 3 investigated nicardipine for primary Raynaud's phenomenon. Oral calcium channel blockers (CCBs) decreased the frequency of attacks (SMD 0.23, 95% CI 0.08 to 0.38; 7 studies, n=358) compared with placebo. This translates to 1.72 (95% CI 0.60 to 2.84) fewer attacks per week on CCBs compared to placebo. Nifedipine studies showed a decrease in the frequency of attacks (SMD 0.32, 95% CI 0.10 to 0.54; 4 studies, n=206) translating to 2.41 (95% CI 0.75 to 4.06) fewer attacks per week on nifedipine compared to placebo. Treatment with CCBs appeared to be associated with a number of adverse reactions, including headaches, flushing and oedema (swelling).
Another meta-analysis 2 included 18 studies with a total of 437 subjects with primary Raynaud's phenomenon; 13 studies compared nifedipine vs. placebo, and 5 compared other CCBs vs. placebo. Meta-analysis (17 studies, n=348) showed that CCBs compared with placebo provided a significant reduction in the frequency of ischaemic attacks over a 1-week period, with a WMD of -5.00 (95% CI -9.02 to -0.99), which means a reduction of about five attacks in a 1-week period. The WMD of all CCBs vs. placebo (8 studies, n=147) for reduction in severity of attacks (assessed with a 10-cm visual analogue scale) was -1.39 (95% CI -2.20 to -0.58). With an average mean severity in the placebo group of 4.25, this can be thought of as a 33% reduction in the severity of attacks. Nifedipine reduced the frequency of attacks (WMD -6.05, 95% CI -11.19 to -0.19) and the severity of attacks on a 10-cm visual analogue scale (WMD -1.81, 95% CI -3.08 to -0.54) compared with placebo.
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