[Systematic review and trail sequential analysis of preparation of Xiakucao for Hashimoto's thyroiditis]

To systemically evaluate the clinical efficacy and safety of oral preparation of Xiakucao with levothyroxine(LT4) on Hashimoto's thyroiditis(HT), so as to provide the evidence for its clinical application in the future. All the included studies were retrieved from four Chinese databases and three English databases from their inception to December 2019. ROB assessment tool of cochrane system and the evidence classification recommended by GRADE were used to evaluate the quality of evidences in all included studies. RevMan 5.3 was used for Meta-analysis of the outcomes. Software TSA 0.9(trail sequential analysis) was used to estimate the sample size for Meta-analysis. The results showed that 11 randomized controlled trials and totaling 1 215 patients were included. Preparation of Xiakucao combined with LT4 was adopted as intervention in experimental group, while patients in control group were treated with LT4 alone. Meta-analysis results showed that as compared with control group, the rate of total efficacy in experimental group was significant improved, including improvement of thyroid function and thyroid autoantibodies, shrinkage of thyroid gland and nodule, and improvement of clinical symptoms such as fatigue and cold intolerance(RR=1.15, 95%CI[1.09, 1.21]). The experimental group significantly decreased the serum level of thyroperoxidase antibody TPO-Ab(SMD=-0.91, 95%CI[-1.40,-0.41]), and reduced the size of left thyroid lobe(MD=-1.46, 95%CI[-1.82,-1.11]), right thyroid lobe(MD=-1.45, 95%CI[-1.96,-0.94]) and isthmus of thyroid gland(MD=-1.08, 95%CI[-1.20,-0.95]). After evaluation based on GRADEpro, the results showed that the evidence quality of all included studies was low or very low. The result of TSA showed that the cumulative sample size had reached the expected value. However, the pooled results may be affected by one study with high bias risk, with not so high effect intensity of evidences. From this review, we can see that in treatment of HT, intervention of preparation of Xiakucao combined with LT4 has advantages on improvement of clinical efficiency, decreasing serum level of TPO-Ab and shrinkage of thyroid gland. However, due to the quality of evidence, more rigorously designed and high-quality trials are needed in the future to verify the clinical efficacy and safety of preparation of Xiakucao in treating HT.