Eight RCTs (109 patients with SSc) were included in the review.
Study quality: the mean quality score was 4.2 points (range: 3 to 5). Order effects were not assessed in any of the crossover RCTs.
Calcium-channel blockers versus placebo (6 crossover RCTs, 59 patients with SSc): calcium-channel blockers significantly reduced the frequency and severity of RP attacks over a 2-week period. The WMD of frequency was -8.31 attacks (95% CI: -15.71, -0.91), while the SMD of severity was -0.69 (95% CI: -1.21, -0.17). No significant heterogeneity was found (P=0.31 for frequency, P=0.4 for severity). The results were similar after excluding the one RCT of nicardipine. There was no significant difference between nicardipine and placebo, but the RCT (15 patients) may have been too small to detect a significant difference.
Calcium-channel blockers versus intravenous iloprost (1 crossover RCT, 23 patients with SSc): there was no significant difference between the treatments in terms of the mean decrease in frequency, duration or severity of RP attacks, or the number of digital ulcers.
Calcium-channel blockers versus losartan (1 RCT, 27 patients with SSc): the RCT did not compare the treatments directly. The authors of the review compared the treatments and found no significant difference between them in the severity or frequency of RP attacks.