Comparison 2. Subgroup analysis by RP type.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Frequency of attacks (average/week)	15	624	Mean Difference (Fixed, 95% CI)	‐3.15 [‐3.67, ‐2.63]
1.1 CCBs vs placebo for primary RP	12	420	Mean Difference (Fixed, 95% CI)	‐3.02 [‐3.65, ‐2.38]
1.2 CCBs vs placebo for secondary RP	9	204	Mean Difference (Fixed, 95% CI)	‐3.42 [‐4.33, ‐2.51]
2 Severity of attacks (average, on a 10‐cm VAS)	10	506	Mean Difference (Fixed, 95% CI)	‐0.67 [‐0.77, ‐0.57]
2.1 Primary RP: CCBs vs placebo	8	368	Mean Difference (Fixed, 95% CI)	‐0.95 [‐1.11, ‐0.79]
2.2 Secondary RP: CCBs vs placebo	6	138	Mean Difference (Fixed, 95% CI)	‐0.48 [‐0.61, ‐0.35]