The efficacy of Chinese patent medicine Xiaojin capsule in the treatment of Hashimoto's thyroiditis: A systematic review and meta-analysis

Introduction: Hashimoto's thyroiditis (HT) is a common autoimmune disease of the thyroid gland and the main cause of hypothyroidism. Currently, Chinese medicine is widely used in clinical treatment, and Chinese patent medicine is more convenient for application. We conducted a meta-analysis of previously published literature to evaluate the efficacy and safety of Xiaojin capsule combined with levothyroxine (LT4) or selenium yeast in the treatment of HT, which also provided evidence-based medical evidence for traditional Chinese medicine in HT treatment. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of Xiaojin capsule on HT. The study was funded by National Natural Science Foundation of China (No. 81973855), and registered on PROSPERO (CRD42023412656). We searched PubMed, Embase, Web of Science, Cochrane Library, Chinese Scientific Journal Database (VIP), WanFang Database, China National Knowledge Information Database (CNKI), and SinoMed from inception to August 15, 2023. Two independent authors reviewed and coded the identified literature. Data analysis was performed using RevMan 5.3 software. We synthesized the results as standardized mean differences (SMD), mean difference (MD) 95 % confidence interval (CI) or relative risk (RR) 95 % CI. The Cochrane Systematic Risk of Bias Assessment Tool was used to assess the quality of the included studies. Results: Thirteen RCTs with 1414 participants were included. The meta-analysis showed that compared with LT4 or selenium yeast alone, oral Xiaojin capsule combined with LT4 significantly reduced serum antibody levels against thyroid peroxidase (TPOAb) (SMD= -3.4, 95 % CI: -4.52 to -2.27, P<0.00001), oral Xiaojin capsule combined with selenium yeast reduced serum TPOAb (MD= -39.13, 95 % CI: -49.97 to -28.3, P<0.00001); oral Xiaojin capsule combined with LT4 significantly reduced serum antibody levels against thyroglobulin (TGAb) (SMD= -3.06, 95 % CI: -4.12 to -1.99, P<0.00001); increased clinical efficiency rate (RR=1.16, 95 % CI: 1.10 to 1.21, P<0.00001) and serum free thyroxine (FT4; SMD=1.18, 95 % CI: 0.47 to 1.88, P <0.00001) levels, and reduced thyroid volume (SMD =-0.59, 95 % CI: -0.87 to -0.32, P<0.0001). The effect on serum free triiodothyronine levels in two groups was not significant, and Xiaojin capsules did not increase the incidence of adverse events. Conclusion: Xiaojin capsule combined with LT4 for treating HT significantly reduced serum TPOAb and TGAb levels, increased serum FT4 levels, and improved goiter. However, the strength of the evidence needs to be improved because of the poor quality of the included studies, and further validation by multiple high-quality randomized controlled trials with comprehensive outcome reporting is needed in the future.