Chinese Herbal Formula Huoxiang Zhengqi for Dampness Pattern in Atopic Dermatitis and Diarrhea-Predominant Irritable Bowel Syndrome: Rationale and Design of a Master Protocol

. Atopic dermatitis (AD) and diarrhea-predominant irritable bowel syndrome (IBS-D) are two recurrent diseases with limited effective treatments. In Chinese Medicine (CM) theory, they may share dampness pattern as the same dominant pathogenesis at a certain stage and, thus, can be treated with the same method. While Chinese herbal formula Huoxiang Zhengqi (HXZQ) has been reported as an effective dampness-resolving therapy for both AD and IBS-D, further high-quality clinical studies are still needed. In addition, HXZQ lacks accurate clinical positioning based on CM patterns. Therefore, we utilize a master protocol design to evaluate HXZQ for dampness pattern simultaneously in AD and IBS-D, with the aim of identifying the pattern-defined population of HXZQ. Methods and Analysis . This master protocol design includes two randomized controlled trials (RCTs) and a real-world observational study. Based on two registry cohorts of AD and IBS-D, patients with dampness pattern will be enrolled in the RCTs to receive either HXZQ oral liquid or a placebo for 4 weeks and then will be followed up for another 4 weeks, while patients with nondampness pattern will constitute the observational study and experience a 12-week follow-up. A total of 678 AD patients and 322 IBS-D patients will be recruited from 14 hospitals in China over a 3-year period. The eczema area and severity index (EASI) and the proportion of responders for adequate relief (AR) are the primary outcomes in AD and IBS-D, respectively. Analysis will be undertaken separately in each substudy, and then an overall analysis combining multiple subgroups will be performed to comprehensively investigate the effect of HXZQ. Discussion . This study will provide high-quality efficacy evidence of HXZQ for AD and IBS-D patients and give an example of postmarketing evaluation for CM products under the pattern dominating different disease research model. The study is registered with ChiCTR1900026700 and ChiCTR1900026837 .