8988 references were retrieved from the bibliographic database search (
FIGURE 1). After excluding 7703 overlapping records, 1285 abstracts were screened for eligibility. After excluding 1109 records, 176 full text articles were assessed for the inclusion in systematic review. Out of these, 61 articles were excluded on the basis of full-text assessment because they did not present research results (n = 32), did not address authorship as defined in the inclusion criteria (n = 22) or had no extractable data (n = 7). The berrypicking search of full articles yielded 8 articles, and no additional relevant articles were identified by experts in the field. Thus the total number of included articles with original data was 123
[8]–
[130], presenting 118 studies (list of articles in
Table S2). All articles were published in English except 1 in Spanish, 1 in Portuguese and 1 in Dutch.