Data management The observation forms were filled out accurately, completely and timely by researchers. Data were recorded electronically by data managers using a double-data entry strategy. The electronic database was collated and locked only by the project manager. The locked electronic database could not be altered. All data regarding this trial were preserved by the Affiliated Hospital of Qinghai University, China. The electronic database was statistically analyzed by a professional statistician. Anonymized trial data will be published at www.figshare.com.