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.