Bibliographic references of scientific articles are the source for calculating impact indexes frequently used for the assignment of funding to research projects. Different citation patterns may result in measurement bias of these impact indexes.
Objective: To analyze citation patterns of Brazilian and Portuguese biomedical journals regarding the geographic origin of the sources cited.
Methods: As part of the v+biomed project, a convenience sample of 11 biomedical journals, 4 Portuguese and 7 Brazilian, was gathered including the following subject categories: General and Internal Medicine, Public Health, Gynecology and Obstetrics, and Surgery. All the references from all the articles published in all the issues (except supplements) in 2009 and 2010 were retrieved. The type of source cited and its geographic origin were analyzed.
Results: A total of 102 issues from the 11 journals, containing 1430 articles, with a total of 32782 references were analyzed. No differences were found regarding the number of authors, pages or references between articles from Brazilian and Portuguese journals. Brazilian journals presented higher prevalence of English language and cited significantly more journals from their own country (30.1%) comparing to Portuguese journals (5.4%). Additionally, a lower citation rate to journals from the other country analyzed was evident in Brazilian (0.1%) when compared to Portuguese (3.2%) journals, as well as a higher self-citation of Brazilian journals (Brazil - 5.6%, Portugal - 2.1%).
Conclusion: A different citation pattern between Portuguese and Brazilian biomedical journals was found, consisting of a higher citation rate from Brazilian to other Brazilian journals and to themselves. This differential in citation patterns may have implications on impact indexes determination which warrant further investigation.