The efficacy and safety of Simiao Xiaobi decoction on rheumatoid arthritis: A systematic review and meta-analysis

Introduction: Simiao Xiaobi decoction (SXD) is a traditional Chinese medicine (TCM) formula that has been clinically applied for rheumatoid arthritis (RA). This meta-analysis aimed to systematically assess the therapeutic efficacy and safety of SXD compared to conventional therapy. Methods: Twelve worldwide databases were searched for randomized controlled trials (RCTs) of treating RA with SXD and comparing non-operative conventional treatments (e.g., medication) from inception to August 2023. Primary outcomes for disease activity were effective rate (ER), joint pain score (JPS), joint swelling score (JSS), and morning stiffness (MS), and secondary outcome measures were laboratory inflammation markers and adverse events. The efficacy was presented as the risk ratio (RR) or mean difference (MD) with 95 % confidence interval (CI) using Review Manager. Risk of bias and the quality of evidence were assessed by using Cochrane "risk of bias" tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Results: A total of 16 RCTs involving 1,749 patients were included. Compared with conventional treatments, SXD monotherapy significantly improved the ER (RR = 1.34, 95 % CI [1.26, 1.43], 14 RCTs, n = 1,578), JPS (MD = -1.00, 95 % CI [-1.33, -0.68], 4 RCTs, n = 327), JSS (MD = -1.59, 95 % CI [-2.12, -1.05], 4 RCTs, n = 327), MS (MD = -0.39, 95 % CI [-0.59, -0.18], 6 RCTs, n = 525), and laboratory results, and SXD add-on therapy significantly improved the ER (RR = 1.22, 95 % CI [1.00, 1.49], 1 RCT, n = 70). Due to some concerns with risk of bias, small sample sizes, and/or inconsistency, the certainty of evidence for SXD monotherapy was moderate for ER, low for JPS and JSS, very low for MS, and very low for SXD add-on therapy. There were fewer cases of adverse events in the SXD group. Conclusion: Our findings suggest that SXD can be a complementary treatment option. However, the methodological quality of the included RCTs was unsatisfactory, so further high-quality research is needed to confirm our results.