'Special issue-ization' as a growth and revenue strategy: Reproduction by the "big five" and the risks for research integrity.

The exponential growth of MDPI and Frontiers over the last decade has been powered by their extensive use of special issues. The "special issue-ization" of journal publishing has been particularly associated with new publishers and seen as potentially "questionable." Through an extended case-study analysis of three journals owned by one of the "big five" commercial publishers, this paper explores the risks that this growing use of special issues presents to research integrity. All three case-study journals show sudden and marked changes in their publication patterns. An analysis of special issue editorials and retraction notes was used to determine the specifics of special issues and reasons for retractions. Descriptive statistics were used to analyse data. Findings suggest that these commercial publishers are also promoting special issues and that article retractions are often connected to guest editor manipulation. This underlies the threat that "special issue-ization" presents to research integrity. It highlights the risks posed by the guest editor model, and the importance of extending this analysis to long-existing commercial publishers. The paper emphasizes the need for an in-depth examination of the underlying structures and political economy of science, and a discussion of the rise of gaming and manipulation within higher education systems.