Quality assessment
At first, after identification and screening of studies, articles were assessed for eligibility, and finally suitable studies were included to the Meta-analysis review. In the present study, The STROBE checklist was used for evaluation of the quality of the selected articles based on title and contents. The STROBE checklist composed of 22 items covering all of the aspects of the methodology such as collection methods, tools, type of the study, definition of the variables, statistical analysis tests, study objectives, sample size and study population.
Depending on the quality analysis, each question was assigned to score one point. In this checklist, the final scores for each study could range from 0 to 44, respectively. Based on the results of the quality assessment, studies were divided into three categories: Low (<15.5), average (15.5–29.5) and high quality (>30) and studies with low-quality scores were excluded from the final meta-analysis.