Oral Chinese Herbal Medicine as Prophylactic Treatment for Episodic Migraine in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background. The prophylactic effects of Chinese herbal medicine (CHM) for migraine were examined in numerous clinical trials. This review aimed to analyze the effectiveness and safety of CHM as prophylactic treatment of migraine compared to flunarizine. Methods. Nine databases were searched for randomized controlled trials (RCTs) that evaluated effects of CHM for episodic migraine prophylaxis compared to flunarizine, published before March 2019. Results. Thirty-five RCTs with 2,840 participants met the inclusion criteria, and 31 of them were included in meta-analyses. The overall meta-analysis indicated that, when compared to flunarizine, CHM reduced the frequency of migraine attacks at the end of treatment (EoT) (21 studies, mean difference (MD) -1.23, 95% confidence interval (CI) (-1.69, -0.76)) and at the end of follow-up (EoFU) (five studies, MD -0.96, 95% CI (-1.70, -0.21)). Subgroup analyses based on the treatment duration, follow-up duration, and the dosage of flunarizine showed that CHM was superior to or comparable with flunarizine in reducing migraine frequency. Similar results were also found for secondary outcomes such as the pain visual analogue scale, migraine duration, responder rate, and acute medication usage. In particular, the studies that used CHM containing herb pairs (Chuan Xiong plus Bai Zhi and Chuan Xiong plus Tian Ma) showed promising results. However, the certainty of this evidence was evaluated as "low"or "very low"using the Grading of Recommendations, Assessment, Development and Evaluations approach. Conclusion. CHM appeared to be comparable with flunarizine in reducing the frequency of episodic migraine attacks in adults at EoT and EoFU and well-tolerated by participants, regardless of the treatment duration, follow-up duration, and dosage of flunarizine. Due to the low certainty of the evidence, the suggested promising prophylactic outcomes require higher quality evidence from further rigorous RCTs.