Modified Sijunzi decoction in the treatment of ulcerative colitis in the remission phase: study protocol for a series of N -of-1 double-blind, randomised controlled trials

Background Modified Sijunzi decoction (SJZD) has been used to treat ulcerative colitis (UC) in remission. However, more rigorous clinical trials are necessary to evaluate its effectiveness. Therefore, a series of single-case randomised controlled trials ( N -of-1 trials) is proposed to compare the efficacy of modified SJZD with mesalazine for treating UC in remission. Methods This is a single-site, hospital-based, double-blind N -of-1 trial for 10 single subjects. Three cycles of N -of-1 trials are planned. There are two treatment periods in each cycle. Modified SJZD combined with mesalazine placebo or mesalazine combined with modified SJZD placebo will be randomised during each 8-week treatment period. There is no washout period in the study. Subjects will be selected by the researcher strictly in accordance with the inclusion and exclusion criteria. Discussion Paired t tests and mixed-effect models will be used to analyse the visual analogue scale (VAS) for clinical symptoms and the quality of life questionnaire responses. The findings will be interpreted with caution. We anticipate that the results will show that modified SJZD is effective for patients with UC in remission. Trial registration Chinese Clinical Trial Register, ID: ChiCTR1900024086 . Registered on 24 June 2019.