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Levels of Evidence in Foot and Ankle Surgery Literature: Progress from 2000 to 2010?
Razi Zaidi, MBBS, BSc, MRCS1; Ali Abbassian, FRCS(Orth)1; Suzie Cro, MSc2; Abherjit Guha, FRCS(Orth)1; Nick Cullen, FRCS(Orth)1; Dishan Singh, FRCS(Orth)1; Andy Goldberg, MD, FRCS(Tr&Orth)1
1 Royal National Orthopaedic Hospital NHS Trust, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom. E-mail address for R. Zaidi: razizaidi@doctors.net.uk
2 MRC Clinical Trials Unit, Aviation House, 125 Kingsway, London, WC2B 6NH, United Kingdom
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Investigation performed at the Foot and Ankle Unit, Royal National Orthopaedic Hospital NHS Trust, Stanmore, United Kingdom

Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

Copyright © 2012 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2012 Aug 01;94(15):e112 1-10. doi: 10.2106/JBJS.K.01453
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The focus on evidence-based medicine has led to calls for increased levels of evidence in surgical journals. The purpose of the present study was to review the levels of evidence in articles published in the foot and ankle literature and to assess changes in the level of evidence over a decade.


All of the articles in the literature from the years 2000, 2005, and 2010 in Foot & Ankle International and Foot and Ankle Surgery, as well as all foot and ankle articles from The Journal of Bone and Joint Surgery (JBJS, American [A] and British [B] Volumes) were analyzed. Animal, cadaver, and basic science articles; editorials; surveys; special topics; letters to the editor; and correspondence were excluded. Articles were ranked by a five-point level-of-evidence scale, according to guidelines from the Centre for Evidence-Based Medicine.


A total of 720 articles from forty-three different countries were analyzed. The kappa value for interobserver reliability showed very good agreement between the reviewers for types of evidence (κ = 0.816 [p < 0.01]) and excellent agreement for levels of evidence (κ = 0.869 [p < 0.01]). Between 2000 and 2010, the percentage of high levels of evidence (Levels I and II) increased (5.2% to 10.3%) and low levels of evidence (Levels III, IV, and V) decreased (94.8% to 89.7%). The most frequent type of study was therapeutic. The JBJS-A produced the highest proportion of high levels of evidence.


There has been a trend toward higher levels of evidence in foot and ankle surgery literature over a decade, but the differences did not reach significance.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Tyler J. Van Heest
    Posted on October 17, 2012
    Levels of Evidence and Impact Factor
    University of Minnesota

    The article “Levels of Evidence in Foot and Ankle Surgery Literature: Progress from 2000 to 2010?” (2012;94:1438), by Zaidi et al. reports that levels of evidence have improved in the last ten years. Furthermore, they discuss impact factor as a measure of a journal’s importance. The authors admit that while impact factor “is not a perfect measure of a journal’s worth, it is the only measure we currently have.”

    The authors need to take their findings a step further and advocate for changing the calculation of impact factor to include levels of evidence. Impact factor only measures whether a journal is being referenced, not the quality of the research being presented.

    Zaidi et al note that the percentage of higher levels of evidence in JBJS-A is more than 2.5x higher than JBJS-B, yet the impact factors are roughly equivalent.

    Impact factor can be skewed in many ways[1]. In 2011, JBJS-A published 509 articles. 135 (26.5%) were of the type that positively skew impact factor (comments, letters, reviews, and editorials). JBJS-B published 289 articles, and 37 (12.8%) were positively skewing publications. The fact that JBJS-B published a much smaller number of articles could explain the high impact factor.

    The advent and further development of the levels of evidence system allows clinicians to assess the quality of a study’s design and gives confidence in the validity of the findings[2]. If clinicians are expected to practice according to evidence-based medicine, journals that publish articles of higher study quality should be considered more important.

    Higher levels of evidence studies were rare in the orthopaedic literature when impact factor was first devised[3]. Zaidi et al. have shown there is now a sufficient proportion of higher level of evidence studies in the literature for it to be incorporated in the calculation of impact factor.


    1. Seglen PO. Citations and journal impact factors: Questionable indicators of research quality. Allergy. 1997;52(11):1050-1056. doi: 10.1111/j.1398-9995.1997.tb00175.x.

    2. Wright J, Swiontkowski M, Heckman J. Introducing levels of evidence to the journal. Journal of Bone and Joint Surgery American volume. 2003;85-A(1):1-3.

    3. Garfield E. Which medical journals have the greatest impact? Ann Intern Med. 1986;105(2):313-320.

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