2.4. Data extraction

Data will be extracted by review of each study for population, mean age, gender, follow-up duration, study design, publishing date, intervention characteristics, and outcomes assessment. The 2 reviewers will create a study-specific speadsheet in Excel (Microsoft Corp.) for data collection. Data extraction will be performed independently, and any conflict will be resolved before final analysis. Any disagreements between the 2 reviewers will be discussed and, if necessary, the third author is referred to for arbitration. If the data are missing or can not be extracted directly, authors will be contacted by email. Otherwise, we calculate them with the guideline of Cochrane Handbook for Systematic Reviews of Interventions 5.1.0. If necessary, we will abandon the extraction of incomplete data.