Table 1 Suggestions for how systematic reviewers can deal with predatory journals

For the review protocol:

1. Detail your methods for addressing the potential for predatory journal articles being captured in your search.

(a) Specify how you will determine if an included article meets the criteria for being in a “predatory” journal [17].

(b) Note how you will deal with included articles you determine to be from “predatory” journals.

For the review:

1. Determine whether included studies are published in open access journals. To do so we suggest the following:

(a) If included studies are published in open access (OA) journals, check to determine if the journal is listed in the DOAJ. If yes, presume the journal is legitimate.

(b) If included OA journals are not listed in the DOAJ, check to see if the journal is a member of COPE (Committee On Publication Ethics). Note that you should check the COPE membership directory, rather than assume a statement of membership on a journals website is accurate. If yes, presume the journal is legitimate.

(c) If included OA journals are not in the DOAJ and not COPE members, review the journal website for characteristics of predatory journals [2]. We suggest that if two or more salient features of predatory journals are present that the journal be classified as predatory.

2. For quantitative analyses, conduct a sensitivity analysis with predatory papers excluded from the synthesis.

3. For qualitative analyses, synthesize results both with and without predatory papers included.

4. Discuss the presence and implications of predatory papers, where relevant.