Efficacy and safety of Shaoyao Gancao Tang for restless leg syndrome: A systematic review and meta-analysis

Restless leg syndrome (RLS) is a common and chronic neurological disease characterized by an irresistible and overwhelming urge to move the legs. In recent years, a growing body of clinical trials has demonstrated that -traditional Chinese herbal medicine Shaoyao Gancao Tang (SG-Tang) may improve RLS. However, a critical examination of the available evidence is warranted. This study aimed to evaluate the efficacy and safety of SG-Tang in the treatment of RLS. The protocol of this study was registered and published at International Prospective Register of Systematic Reviews (PROSPERO; CRD42020173520). Randomized clinical trials (RCTs) on the efficacy and safety of SG-Tang in the treatment of RLS were identified by searching the Cochrane Library, PubMed, EMBASE, Web of Science, the Chinese Biological Medicine Database, China National Knowledge Infrastructure, Wanfang Database, and VIP Information Database from inception to February 14, 2022. The primary outcome measurements were the total effective rate, and the secondary outcome measurements included the International Restless Legs Syndrome Study Group Rating Scale for Severity of Restless Legs Syndrome (IRLS), the Pittsburgh Sleep Quality Index (PSQI), and the incidence of adverse events. The Review Manager 5.3 software was utilized to conduct quantitative synthesis according to the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Six eligible RCTs were included in this meta-analysis. Compared to conventional medications, SG-Tang intervention showed significant improvements in the total effective rate (risk ratio [RR] = 1.22, 95% confidence interval [CI] (1.09,1.36), P = 0.004), the IRLS (mean difference [MD] = −4.74, 95% CI (−8.65, −0.83), P = 0.02), and the PSQI (MD = −2.54, 95% CI (−4.34, −0.74), P = 0.006) with less incidence of adverse events (RR = 0.21, 95% CI (0.09, 0.31), P = 0.0005). SG-Tang may be effective and safe as a complementary and alternative treatment to relieve RLS. However, the results need to be interpreted with caution because of limited data and the undesirable methodological quality of the included studies. More well-designed, large-scale, high-quality, and multi-center RCTs are required to be performed for further verification.