Background: There is an established trend towards an increasing number of authors per article in prestigious journals for medicine and health sciences. It is uncertain whether a similar trend occurs to the same extent in journals for specific medical specialties.
Methods: Journals focusing on occupational medicine were selected for analysis with regard to single or multiple-authorship per peer-reviewed paper. Data were collected from PubMed for publications between 1970 and 2007. These were analysed to calculate the average number of authors per multiple-author article per year and the percentage of single-author articles per year. The slope and average of these journals were then compared with that of previously studied non-occupational medicine journals.
Results: The results confirm a trend towards a linear increase in the average number of authors per article and a linear decrease in the percentage of single-author articles. The slope for the average number of authors for multiple-author articles was significantly higher in the Journal of Occupational and Environmental Medicine than in the other occupational medicine journals. Computational analysis of all articles published showed that Occupational Medicine (Oxford) had a significantly higher percentage of single-author articles than the other occupational medicine journals as well as major journals previously studied.
Conclusion: The same trend towards multiple authorship can be observed in medical specialty journals as in major journals for medicine and health sciences. There is a direct relationship between occupational journals with higher impact factors and a higher average number of authors per article in those journals.