Comparison 1. CCBs vs placebo (generic inverse variance method).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Frequency of attacks (average/week)	23	1024	Mean Difference (Fixed, 95% CI)	‐6.07 [‐6.53, ‐5.61]
2 Frequency of attacks (average/week)	22		Mean Difference (Fixed, 95% CI)	‐2.93 [‐3.44, ‐2.43]
3 Duration of attacks (minutes)	6	138	Mean Difference (Fixed, 95% CI)	‐1.67 [‐3.29, ‐0.04]
4 Severity of attacks (average, on a 10‐cm VAS)	16	748	Risk Difference (Fixed, 95% CI)	‐0.62 [‐0.72, ‐0.51]
5 Pain (10‐cm visual analogue scale)	4	124	Std. Mean Difference (Fixed, 95% CI)	‐1.47 [‐2.21, ‐0.74]
6 Patient global	2	192	Std. Mean Difference (Fixed, 95% CI)	‐0.37 [‐0.73, ‐0.02]
7 Number of withdrawals (due to treatment)	2	63	Risk Ratio (M‐H, Fixed, 95% CI)	1.30 [0.51, 3.33]