[Multiple authorship: growth or inflationary bubble?]

To analyze the increase in number of authors per article in Brazilian scientific journals on public health.

Articles published between 1999 and 2010 in six journals on public health and one medical journal (for comparison) from SciELO with Qualis (Capes) classification equal or superior to B-1, were searched on the LILACS database. The evolution of the median number of authors/article and the proportion of articles with more than four authors were evaluated. The association between the the triennium of publication and the presence of four or more authors per paper was estimated through the Mantel-Haenzel odds ratio, adjusted for the type of journal.

An increase of the median number of authors and the proportion of articles with more than four authors was observed in all journals, especially in the last triennium. The odds ratio for articles with four or more authors, adjusted for the type of journal, were: second triennium 1.3 (95%CI 1.1;1.4); third triennium 1.5 (95%CI 1.3;1.8), fourth triennium 2.39 (95%CI 2.1;2.8).

Scientific journals on public health have shown an increase in the number of authors per article over the years, regardless of editorial orientation.