Bias against European journals in medical publication databases

Abstract

Bias or any process leading to the deviation from the truth can be introduced in many ways into the process of locating and selecting articles for references or inclusion in meta-analysis and literature reviews. 1 Egger M Smith GD Bias in location and selection of studies. BMJ. 1998; 316: 61-66 Crossref PubMed Scopus (1023) Google Scholar Studies with statistically significant results are more likely to get published than studies showing no statistically significant associations or differences, leading to publication bias. 2 Begg CB Berlin JA Publication bias: a problem of interpreting medical data. J R Statist Soc A. 1988; 151: 419-463 Crossref Google Scholar There are coverage problems in the available medical-publication databases. In particular, it has been claimed that the source journals for Medline have a considerable bias in favour of US and other English language journals. 3 Egghe L Rousseau R Introduction to informetrics: quantitative methods in library, documentation and information science. Elsevier, Amsterdam1990 Google Scholar Studies published in journals not indexed in major databases are effectively hidden from researchers. Coverage bias may thus have been introduced when the acquisition of subject data by authors and readers of medical reports include only a selection of all possible literature related in content to their own work. Characteristics between articles published in indexed and non-indexed journals might differ, leading to database bias. 4 Egger M Zellweger-Zähner T Schneider M Junker C Lengeler C Antes G Language bias in randomised controlled trials published in English and German. Lancet. 1997; 350: 326-329 Summary Full Text Full Text PDF PubMed Scopus (805) Google Scholar