Authorship concentration in health sciences journals from latin america and the caribbean

Objective: to describe authorship concentration indexes (proportion of articles by the most prolific author [PPMP]; Gini coefficient) among health sciences journals indexed in LILACS, and to compare them to what a previous study found in MEDLINE. Methods: bibliographic data were obtained from LILACS for systematically indexed journals with at least 50 signed articles (that is, with at least one individual author) from 2015 to 2019. Authors were identified by their name or, when possible, ORCID id. The PPMP was the number articles by the journal's most prolific author, divided by the number of signed articles. The Gini coefficient counted more than once articles with multiple authors. For comparison purposes, MEDLINE data were reweighted to have the same distribution of journal size (number of signed articles) as LILACS journals. Results: the study included 568 journals, with a median size of 166 signed articles. The median PPMP was 4.5% (95th percentile 12.9%), and the median Gini coefficient was 0.149 (95th percentile 0.310). The PPMP increased with journal size, while the Gini coefficient decreased. MEDLINE journals had lower PPMP and higher Gini coefficients, but this difference disappeared after the data were reweighted. Conclusions: LILACS inclusion criteria are effectively countering any pro-endogeneity effect ownership by universities might have on regional journals. Journal evaluation should mind journal size when examining authorship concentration indexes. Formal derivation of their relationship with journal size would allow more precise interpretation of such indexes.