Research Article: Research Trends in Evidence-Based Medicine: A Joinpoint Regression Analysis of More than 50 Years of Publication Data

Date Published: April 7, 2015

Publisher: Public Library of Science

Author(s): Bui The Hung, Nguyen Phuoc Long, Le Phi Hung, Nguyen Thien Luan, Nguyen Hoang Anh, Tran Diem Nghi, Mai Van Hieu, Nguyen Thi Huyen Trang, Herizo Fabien Rafidinarivo, Nguyen Ky Anh, David Hawkes, Nguyen Tien Huy, Kenji Hirayama, Jakob Pietschnig.


Evidence-based medicine (EBM) has developed as the dominant paradigm of assessment of evidence that is used in clinical practice. Since its development, EBM has been applied to integrate the best available research into diagnosis and treatment with the purpose of improving patient care. In the EBM era, a hierarchy of evidence has been proposed, including various types of research methods, such as meta-analysis (MA), systematic review (SRV), randomized controlled trial (RCT), case report (CR), practice guideline (PGL), and so on. Although there are numerous studies examining the impact and importance of specific cases of EBM in clinical practice, there is a lack of research quantitatively measuring publication trends in the growth and development of EBM. Therefore, a bibliometric analysis was constructed to determine the scientific productivity of EBM research over decades.

NCBI PubMed database was used to search, retrieve and classify publications according to research method and year of publication. Joinpoint regression analysis was undertaken to analyze trends in research productivity and the prevalence of individual research methods.

Analysis indicates that MA and SRV, which are classified as the highest ranking of evidence in the EBM, accounted for a relatively small but auspicious number of publications. For most research methods, the annual percent change (APC) indicates a consistent increase in publication frequency. MA, SRV and RCT show the highest rate of publication growth in the past twenty years. Only controlled clinical trials (CCT) shows a non-significant reduction in publications over the past ten years.

Higher quality research methods, such as MA, SRV and RCT, are showing continuous publication growth, which suggests an acknowledgement of the value of these methods. This study provides the first quantitative assessment of research method publication trends in EBM.

Partial Text

From the 1900s until now, evidence-based medicine (EBM) has developed into the dominant paradigm for clinical practice [1–3]. Although the term EBM officially appeared for the first time in 1992 in an article by Guyatt et al in JAMA [4], traces of the origins of EBM dated back to ancient Greece [5,6]. By 1996, EBM was formally defined as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients” by Sacket et al [7] and this definition has been recognized and strongly endorsed by most of the world’s scholarly articles on EBM [8–10]. It is important to note that while often used interchangeably, EBM and science-based medicine (SBM) are related but different terms. SBM is a subset of EBM which not only involves evidence for treatment efficacy but also a mechanism by which the effect can occur. One (historical) example of a treatment that is EBM but not SBM is a number of different forms of anaesthetic which have been clearly shown to work but the mechanism remains unclear [11]. Internationally, EBM now provides the framework for the diagnosis and treatment of most health conditions [12–14]. The alternative to EBM is empirical diagnosis and treatment, which is a system much more open to individual, cultural and training bias [15]. Overall this approach has become less popular as health practitioners have greater access to cutting edge medical knowledge in the current information era. The increasing rate of research and knowledge acquisition often means that clinicians are asked questions the answers to which have changed since their training [16]. Patients expect physicians to be able to interpret and explain medical information from a wide range of sources including the internet [11,17]. Insurers expect physicians to know which diagnostic and treatment strategies strike the best balance between accuracy and cost effectiveness [18]. While students need to rapidly assess medical information and its quality, they must also learn to make decisions in the absence of good evidence [19]. EBM provides a framework for using medical and scientific evidence to effectively guide clinical practice, and as such is thoroughly prepared to match all of these challenges [4,12,19–21].

From the PubMed database, a total of 22,134,520 publications were extracted from the years 1945–2012. PGL and CR accounted for 0.08% and 6.75%, respectively, of APP, and comprised the smallest and largest categories of publication. The most recent year examined (2012) had the highest annual number of publications in each article type, except for CCT, which peaked in 1997. Among all publication types, PGL accounted for the least number of total papers (17,673 papers). RCT, SRV and MA accounted for a relatively small number of total publications (344,714 for RCT; 178,155 for SRV and 38,167 for MA). Non-RCTs accounted for 364,315 papers. (Table 1) (Fig 2).

This study demonstrates that article types with higher levels of evidence accounted for fewer publications than those with lower levels of evidence. One possible reason for this observation is that systematic review (SRV), randomized controlled trial (RCT), and meta-analysis (MA) articles may take longer to publish because of the time needed for establishing study design, data collection and analysis, as well as for peer review [55–57]. These article types also need more financial, technical and human resources to conduct. Data for SRV and MA are collected from available clinical trials, cohort studies, case-control studies, observational studies, etc. [55,56]. Additionally SRVs and MAs can only occur after a sufficient body of research has been undertaken which may take years if not decades. As a result of their inherent design, SRV and MA will mostly be produced at a much lower rate than other publication types which are ranked as having a lower quality of evidence. Similar to the case of SRV, RCT and MA, publishing practice guideline (PGL) is also time-consuming because of the time it takes to manage conflicts of interest, to assess the quality of evidence and to facilitate the consensus [58]. Case reports (CR) are ranked as being of the lowest quality of evidence but are nonetheless important for generating hypotheses for further studies to resolve new issues [37,59,60].

In conclusion, quantitative growth was found across all publication types. The growth of all, rather than only some publication types, is necessary for the development of EBM, because evidence-based medicine develops in a step-by-step manner: evidence from low-quality studies serve as data points for conducting larger/better designed studies which provide stronger evidence. Current trends may predict that SRV and MA will continue to grow in the future. RCT is getting priority over the other subset of CT; and although the proportion of RCT to CT has recently shown a stable but significantly increasing trend, RCT is still important in order to gain valuable robust evidence needed for better health care outcomes. This current study provides the first large scale quantitative analysis of EBM publication trends.