Trials screening and data extraction
Trials with indications of ”er” in pediatric patients in Chinese or ”adolescent” were retrieved for inclusion. Two authors have respectively screened the retrieved trials, and excluded the repeated registration trials, trials that have been suspended, non-drug trials, and trials without indications for children. Two authors have reviewed the full information of all the included trials and extracted the study characteristics, and any disagreements were resolved through discussion or by consulting a third author. The following information of the trials, including registration number, trial status, trial phase, date of first ethical approval, name of the sponsor and province of the sponsor located, the first affiliation and province of the principal investigator located, number of research centers, name, type, dosage form and indications of the drug studied, age of the subjects, children’s age specified in the indication, whether a data monitoring committee (DMC) have been established, and whether insurance had been purchased for participants, were recorded. We defined the first ethical approval date of the trials as the date of the trials to make annual trial number statistics. The provinces of the sponsor and the principal investigator were divided into seven regions according to the China’s seven geographical divisions, the north, east, south, central, northeast, northwest and the southwest. For foreign sponsors, their registered province was recorded in China. For drugs with indications for adults and children, only the indications for only children were recorded. In this study, the indications of studied drugs were coded according to the International Statistic Classification of Diseases and Related Health Problems, Tenth Revision, International Classification of Diseases (ICD)-10 classification.