The authors respond to “Rigorous policies ensure integrity of NLM literature databases”
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* Andrea Manca
* David Moher
* Lucia Cugusi
* Zeevi Dvir
* Franca Deriu

An important goal of our article published in *CMAJ*, “How predatory journals leak into PubMed,”1 was to ignite a thoughtful debate on the perilous issue of predatory journals contaminating trusted sources of information, such as legitimate biomedical databases. Feedback from the US National Library of Medicine is the ideal starting point for the discussion, and we thank Dr. Topper and colleagues for their recent letter.2

The topic — how journals are included in PubMed and PubMed Central and, more broadly, the multilayered policies of PubMed and the National Library of Medicine — is too complex and articulated to be comprehensively and concisely summarized and was beyond the remit of our article.1 However, we do not believe we made incorrect statements about PubMed and National Library of Medicine policies. We also do not question either the rigorous assessment of scientific and editorial quality of journals that apply to PubMed Central or the election criteria used by the National Library of Medicine to re-evaluate previously accepted journals.

Our point is that “predators” continue to appear in PubMed, despite the profound commitment of the National Library of Medicine toward the integrity of its literature databases. Thus, regardless of whether it is the journal or only 1 or more individual journal articles to appear in PubMed or PubMed Central, as Topper and colleagues suggested,2 the result is the same: the items achieve global exposure and are interpreted by readers, including patients, as trustworthy.

We understand that operating in such challenging times in the scholarly publishing environment is undoubtedly very complex. However, this quicksand should not discourage continued work to secure PubMed from contamination by the outputs of deceptive journals and publishers.

## Footnotes

*   **Competing interests:** None declared.

## References

1.  Manca A, Moher D, Cugusi L, et al. How predatory journals leak into PubMed. CMAJ 2018;190:E1042–5.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMjoiMTkwLzM1L0UxMDQyIjtzOjQ6ImF0b20iO3M6MjI6Ii9jbWFqLzE5MS8xMC9FMjkwLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

2.  Topper L, Marill J, Kelly C, et al. Rigorous policies ensure integrity of NLM literature databases. CMAJ 2019;191:E289.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTkxLzEwL0UyODkiO3M6NDoiYXRvbSI7czoyMjoiL2NtYWovMTkxLzEwL0UyOTAuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9)