Predatory medical journals: Finding nuggets among dross

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Increasing numbers of studies published by predatory journals are appearing in leading biomedical databases. The challenge in meta-analyses and systematic reviews is to efficiently exclude the mass of poor quality material while not excluding eligible research, according to a study in Systematic Reviews.

The Canadian study, published this month, is by Danielle B Rice of McGill University in Montréal, and Becky Skidmore and Kelly D Cobey of the Ottawa Hospital Research Institute.

Systematic reviews are intended to critically appraise and synthesise the results of entire bodies of literature. In healthcare, they may be used in the development of clinical practice guidelines. The utility of systematic reviews, however, depends on the quality of the included studies.

An emerging methods concern among systematic review teams is that they may unknowingly capture studies published in “predatory” journals. This may degrade the quality of a systematic review, and in medicine, has the potential to create downstream effects that negatively impact patient care.

Predatory journals often exploit the open access (OA) publishing model, where copyrights are typically retained by authors, and work is free to access and build upon. Predatory journals may promote themselves as “OA” to earn a profit from APCs, but without meeting expected publication best practices. For example, they may not provide peer review.

Examples of the public making medical decisions based on articles published in predatory journals have been noted previously]. Further, a study examining 1,907 biomedical studies in presumed predatory journals demonstrated that less than half of the included studies reported having ethics approval, yet more than two million humans were included in the predatory publications.

Overall, the quality of articles was far worse than research published in non-predatory journals. Within this sample, however, there were articles that were of similar quality to research published in non-predatory journals. For example, 14% of trials (n = 13) were registered.

Being unable to retrieve these articles due to a lack of indexing in common databases, or choosing to disregard these trials solely due to being published in a predatory journal may impact the conclusions drawn during a systematic review and does not fulfil the goal of a systematic review in providing a comprehensive overview of all eligible studies.

The counterpoint to this is that availability of findings in predatory journals also poses a threat, since this could result in unvetted research being used, and in the case of systematic reviews, potentially then integrated into clinical decision making. Results from articles published in predatory journals have been included in systematic reviews previously and can alter findings and recommendations made based on knowledge synthesis.

The presence of predatory journals in databases has been increasing in recent years with Google Scholar and PubMed, one of the world’s leading biomedical databases, both including articles from predatory journals.

This begs the question: what actions should systematic review teams take to deal with presumed predatory journal articles? To fulfil the goals of a systematic review by critically appraising and synthesising results from an entire body of literature, the inclusion of articles published in predatory journals is necessary.

Systematic reviews should apply standardised approaches to identify articles that are eligible for a systematic review, including those published in predatory journals and conduct thorough risk of bias assessments to determine the impact of these articles in the synthesis of findings.

The recommendations [derived from this study] allow articles in potentially predatory journals to be included in systematic reviews while taking into consideration the poor quality that is common among articles published in potentially predatory journals.


Study details

Dealing with predatory journal articles captured in systematic reviews

Danielle B Rice, Becky Skidmore and Kelly D Cobey

Published in Systemic Reviews on 10 June 2021.



Systematic reviews appraise and synthesize the results from a body of literature. In healthcare, systematic reviews are also used to develop clinical practice guidelines. An increasingly common concern among systematic reviews is that they may unknowingly capture studies published in “predatory” journals and that these studies will be included in summary estimates and impact results, guidelines, and ultimately, clinical care.

There is currently no agreed-upon guidance that exists for how best to manage articles from predatory journals that meet the inclusion criteria for a systematic review. We describe a set of actions that authors of systematic reviews can consider when handling articles published in predatory journals: (1) detail methods for addressing predatory journal articles a priori in a study protocol, (2) determine whether included studies are published in open access journals and if they are listed in the directory of open access journals, and (3) conduct a sensitivity analysis with predatory papers excluded from the synthesis.

Encountering eligible articles published in presumed predatory journals when conducting a review is an increasingly common threat. Developing appropriate methods to account for eligible research published in predatory journals is needed to decrease the potential negative impact of predatory journals on healthcare.


Full study in Systematic Reviews – Dealing with predatory journal articles captured in systematic reviews (Open access)




Research ‘polluted’ by plagiarism, fraud and predatory publishing


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