Randomization and Blinding
Eligible patients were randomly assigned at a 1:1 ratio to receive mifepristone or placebo. The randomization sequence was generated by a statistician using the block-rank package in R software version 3.4.1 (R Project for Statistical Computing) and was stratified by center with a block size of 4. Randomization was performed centrally with an interactive web response system. The participant and drug numbers were all unique and corresponded to one another and were handled independently by the other designated statistician. Additionally, confidentiality was maintained for the clinician and patients. None of the statisticians participated in any part of the trial.The placebo tablets had the same appearance (size, shape, and color) as the mifepristone tablets. The route and administration of the assigned intervention were identical in the 2 groups. When a patient submitted written informed consent and agreed to participate in the trial, the interactive web response system temporarily generated a corresponding drug code, and then the drug with the code was allocated to the patient. Allocation concealment was maintained by blinding the patients, investigators, clinicians, and statisticians until the study was completed.