The authors respond to "Rigorous policies ensure integrity of NLM literature databases

An important goal of the Analysis by Manca and Colleagues (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 U.S. National Library of Medicine (NLM) is the ideal starting point for the discussion to begin, for which we thank Dr. Topper and Colleagues for their recent commentary (2). The topic, how journals are included in PubMed and PubMed Central (PMC) and, more broadly, the multi-layered PubMed and NLM policies, is too complex and articulated to be comprehensively and concisely summarized and, was beyond the remit of our analysis (1). However, we do not believe we made incorrect statements about PubMed and NLM policies; we do not question either the rigorous assessment of scientific and editorial quality of journals that apply to PMC or the election criteria used by NLM to re-evaluate previously accepted journals. Our point is that ‘predators’ continue to appear in PubMed, despite the profound commitment of NLM towards the integrity of its literature databases. Thus, regardless of whether it is the journal or only one or more individual journal articles to appear in PubMed/PMC, as Topper and Colleagues objected (2), the result is the same: the items are displayed jointly and achieve global exposure and are interpreted by readers, including patients, as trustworthy. We understand that to operate in such challenging times in the scholarly publishing environment is undoubtedly very complex. However, this quicksand should not discourage from continuing to work to secure PubMed from contamination by the outputs of deceptive journals and publishers.