Global mapping of randomised trials related articles published in high-impact factor medical journals: a cross-sectional analysis
Authors: Catalá-López Ferrán , Aleixandre-Benavent Rafael , Caulley Lisa , Hutton Brian , Tabarés-Seisdedos Rafael , Moher David , Alonso-Arroyo Adolfo 
Published: July 2019

Abstract
Background
Randomised controlled trials (RCTs) provide the most reliable information to inform clinical practice and patient care. We aimed to map the global clinical research publication activity through RCTs related articles in high-impact factor medical journals over the past five decades.

Methods
Cross-sectional analysis of articles published in the highest ranked medical journals with an impact factor > 10 (according to Journal Citation Reports published in 2017). We searched PubMed/MEDLINE (from inception to December 31, 2017) for all RCTs related articles (e.g. primary RCTs, secondary analyses and methodology papers) published in high-impact factor medical journals. For each included article, raw metadata were abstracted from the Web of Science. A process of standardization was conducted to unify different terms and grammatical variants and to remove typographical, transcription, and/or indexing errors. Descriptive analyses were conducted (including the number of articles, citations, most prolific authors, countries, journals, funding sources and keywords). Network analyses of collaborations between countries and co-words were presented.

Results
We included 39305 articles (period 1965-2017) published in forty journals. The Lancet (n=3593; 9.1%), the Journal of Clinical Oncology (n=3343; 8.5%), and The New England Journal of Medicine (n=3275 articles; 8.3%) published the largest number of RCTs. 154 countries were involved in the production of articles. The global productivity ranking was led by the United States (n=18393 articles), followed by the United Kingdom (n=8028 articles), Canada (n=4548 articles) and Germany (n=4415 articles). Seventeen authors who published 100 or more articles were identified; the most prolific authors were affiliated with Duke University (United States), Harvard University (United States), and McMaster University (Canada). Main funding institutions were the National Institutes of Health (United States), Hoffmann-La Roche (Switzerland), Pfizer (United States), Merck Sharp & Dohme (United States) and Novartis (Switzerland). The 100 most cited RCTs were published in 9 journals, led by The New England Journal of Medicine (n=78 articles), The Lancet (n=9 articles) and JAMA (n=7 articles). These landmark contributions focused on novel methodological approaches (e.g. “Bland-Altman method”) and trials on the management of chronic conditions (e.g. diabetes control, hormone replacement therapy in postmenopausal women, multiple therapies for diverse cancers, cardiovascular therapies such as lipid-lowering statins, antihypertensive medications, antiplatelet and antithrombotic therapy).

Conclusions
Our analysis identified authors, countries, funding institutions, landmark contributions and high-impact factor medical journals publishing RCTs. Over the last 50 years, publication production in leading medical journals has increased with research leadership of Western countries, but with very limited representation from low and middle-income countries.