A Synthetic External Control Study Comparing the Clinical Efficacy of Wendan Decoction and 19 Antidepressants

Background Wendan decoction (WDD) has been used as a treatment for depression in China since the Tang Dynasty. However, high-quality evidence for this is lacking. This study proposed a novel synthetic external control method to evaluate its clinical efficacy. Methods We searched public databases for clinical trials of WDD for major depression. The rate of change of the Hamilton Depression Scale score from baseline was used as an efficacy indicator, and a model-based meta-analysis was performed to analyze the clinical efficacy of WDD. To establish a reference standard for efficacy, the antidepressant efficacy distributions of a placebo and 19 antidepressants were virtually synthesized based on the same conditions as the clinical trial characteristics of WDD. Results This study included 5 clinical trials with 177 participants. WDD showed a slow onset, with a time to reach the maximum effect of 9.71 weeks. At 8 weeks, the rate of change in the Hamilton Depression Scale score from baseline was 66.4% (95% CI = 62.3%-70.3%) in the WDD group. The pure effect value of WDD, after deducting the placebo effect, was 26.9% (95%CI = 23.0%-30.9%), which was comparable with 5 types of antidepressants and significantly higher than the others. Conclusion The proposed external synthetic control method provides a solution to the bottleneck problem of clinical efficacy evaluation in real-world research on traditional Chinese medicine. WDD has high clinical development value for the treatment of depression, and large-scale randomized controlled trials are recommended to confirm its antidepressant effect.