Do journals raise their impact factor or SCImago Ranking by self-citing in editorials? A bibliometric analysis of trauma and orthopaedic journals

Background: Impact factor (IF) is widely accepted as a measure of a journal's quality but it can be influenced by self-citation. However, the SCImago Journal Rank (SJR) is based on journal prestige, excludes self-citation and considers quality of citations of a journal. This study aimed to investigate journal editors' use of self-citation and whether this correlated with IFs or SJR in trauma and orthopaedic (T&O) journals. Methods: T&O journals on the SJR database were identified. From each journal, data including country of publication, number of annual issues, IF, SJR indicator and citable articles were extracted. The editorial(s) of each issue in 2018 were reviewed. The total number of times the editors cited their own previous work or their journal (in the preceding 2 years, 2016–2017) were identified. Regression analyses were performed to investigate the association of editorial self-citation with journal IF or SJR indicator. Results: Of the 270 journals identified, 43 T&O journals with 151 editorials were included in the final analysis. A positive correlation between journal self-citation in the editorial and IF (P = 0.02) and SJR indicator (P = 0.02) was found. Citation by editors of their own publications within editorials also positively correlated with IF (P = 0.04) but not for SJR indicator (P = 0.19). There was a positive linear relationship between journal IF and SJR indicators (P < 0.01). Conclusion: Editor self-citation influences the IF and SJR indicators in T&O journals. Therefore, these metrics should be considered in conjunction with other factors such as audience, topics included and international presence when evaluating journals