FIGURE 1.

The schematic representation of the search method. Following the initial search, 273 records were retrieved. Ten duplicates were removed. Subsequently, 178 records were removed due to irrelevance after the titles were screened. Thereafter, 30 records were excluded due to the irrelevance of the abstracts. Finally, 34 full-text articles were removed because some did not satisfy the inclusion criteria and the others were not original articles. Thus, 21 articles that satisfied the inclusion criteria were included in the study. N = number.