Demographic characteristics of Systematic Reviews, Meta-Analyses and Randomized Controlled Trials in non-orthodontic journals with impact factor

Abstract

The purpose of this study was to identify authorship characteristics of all orthodontic systematic reviews (SRs), meta-analyses (MAs) and randomized controlled trials (RCTs) published in non-orthodontic journals with Impact Factor (IF). The outcomes of this investigation will reveal authorship trends in high impact orthodontic articles published in non-orthodontic journals. This study identified all SRs, MAs and RCTs published in non-orthodontic journals with IF, until December 2015. Detailed search strategies were developed for every database searched which was based on the strategy developed for MEDLINE but revised appropriately for each database to take account of the differences in controlled vocabulary and syntax rules. The following electronic databases were searched: MEDLINE via PubMed, Scopus, Web of Science™ Core Collection, Google Scholar, and Ovid database. Each database was searched individually and included all the articles published until December 2015. No restrictions were applied during the electronic search regarding language or publication status. However, articles without an abstract in English were excluded. A total of 4524 articles were found. After deleting duplicated results, letters, comments, books, and articles published in orthodontic journals 1860 articles remained. After reviewing each article, we ended up with 274 articles in total (SRs: 152; MAs: 36; RCTs: 86). In general, most of the articles published were SRs (55.5%) followed by RCTs (31.4%) and MAs (13.1%). North America (52.2%), European Union countries (56.7%), non-European Union countries (64.3%), and Central and South America (53.6%), all are concentrating in publishing SRs mostly followed by RCTs (North America 32.6%; European Union countries 34.6%; non-European Union countries21.4%; and Central and South America 32.1%). On the other hand, authors in Asia concentrated more on SRs (56.9%) and published RCTs (21.6%) and MAs (21.6%) to almost the same extent. Similar trends applied to authors in Africa (SRs: 60%; MAs: 20%; RCTs: 20%). Oceania presented only publications of RCTs. All three kinds of articles were mostly published during the period of 2006-2015 and most of the regions presented an increase in publications in this period. It was shown that in both periods most of the articles were published in non-orthodontic dental journals (before 2006: 65.8%; during 2006-2015:64.8%). Regarding the number of authors, RCTs had mostly four or more authors (23.3%), SRs had mostly five authors (21.1%) and MAs had three authors (30.6%). It was noticed that in both periods the majority of studies had four authors (21.1% and 20.8%, respectively). Orthodontic literature of a high level published in non-orthodontic journals has significantly increased during the last decade (2006-2015) and has been concentrated mostly in dental journals characterized mainly by an increase in publishing SRs. During the period 2006-2015 there was a significant increase in published articles originating from Asia compared to similar contributions by European Union countries, whose output exhibited a slight decline over the period.