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Review
Statistical testing of baseline differences in sports medicine RCTs: a systematic evaluation
  1. Ross L Peterson1,
  2. Matthew Tran2,
  3. Jonathan Koffel3,
  4. Steven D Stovitz4
  1. 1 Division of Biostatistics, University of Minnesota School of Public Health, Minneapolis, Minnesota, USA
  2. 2 College of Biological Sciences, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
  3. 3 Health Sciences Libraries, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
  4. 4 Family Medicine and Community Health, University of Minnesota Medical School Twin Cities, Minneapolis, Minnesota, USA
  1. Correspondence to Ross L Peterson; pet00180{at}umn.edu

Abstract

Background/Aim The CONSORT (Consolidated Standards of Reporting Trials) statement discourages reporting statistical tests of baseline differences between groups in randomised controlled trials (RCTs). However, this practice is still common in many medical fields. Our aim was to determine the prevalence of this practice in leading sports medicine journals.

Methods We conducted a comprehensive search in Medline through PubMed to identify RCTs published in the years 2005 and 2015 from 10 high-impact sports medicine journals. Two reviewers independently confirmed the trial design and reached consensus on which articles contained statistical tests of baseline differences.

Results Our search strategy identified a total of 324 RCTs, with 85 from the year 2005 and 239 from the year 2015. Overall, 64.8% of studies (95% CI (59.6, 70.0)) reported statistical tests of baseline differences; broken down by year, this percentage was 67.1% in 2005 (95% CI (57.1, 77.1)) and 64.0% in 2015 (95% CI (57.9, 70.1)).

Conclusions Although discouraged by the CONSORT statement, statistical testing of baseline differences remains highly prevalent in sports medicine RCTs. Statistical testing of baseline differences can mislead authors; for example, by failing to identify meaningful baseline differences in small studies. Journals that ask authors to follow the CONSORT statement guidelines should recognise that many manuscripts are ignoring the recommendation against statistical testing of baseline differences.

  • randomised controlled trial
  • sports medicine
  • statistics
  • testing

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjsem-2017-000228

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    Footnotes

    • Acknowledgements The authors would like to acknowledge Alan M Batterham, PhD, and Ian Shrier, MD, PhD, for their helpful comments on earlier versions of this manuscript.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.