Figure 1: Review stages based on PRISMA flow diagram
The results of the search process are summarized into a PRISMA flow diagram (Figure 1). Out of a total of 909 papers selected, 326 duplicates were removed. After screening the search in PubMed yielded 278, in Web of Science 302, in Cinahl 158 and in the Cochrane Library 159 articles. Through the snowballing method of screening the reference lists of relevant articles, 12 additional articles complying with the inclusion criteria could be identified and were added.
After screening 583 papers on title and abstract 63 papers remained for full-text screening. From these, 36 articles were subjected to quality assessment.