Sports Medicine Research: In the Lab & In the Field: Balance Error Scoring System & a Need for Reliability in the Clinic (Sports Med Res)


Friday, June 3, 2011

Balance Error Scoring System & a Need for Reliability in the Clinic

Systematic Review of the Balance Error Scoring System

David R. Bell, Kevin M. Guskiewicz, Micheal A. Clark, and Darin A. Padua Sports Health: A Multidisciplinary Approach May/June 2011 vol. 3 no. 3 287-295

Many studies have demonstrated the importance of balance and balance training for activities of daily living and sport. For patients with severe balance deficiencies (e.g., post stroke) there are some well validated clinical measures (e.g., Berg Balance Scale, Tinetti Balance Assessment Tool) that do not require advance equipment (e.g., force plates). Among the athletic population there are very few balance assessments that incorporate multiple tasks, can be performed in a traditional clinical setting, and have been validated for several conditions. The Balance Error Scoring System (BESS), originally developed for assessing concussions, is one commonly used assessment consisting of three stances (feet together, single-leg stance, and tandem stance) performed on a firm and foam surface for 20 seconds each (the outcome score is based on the number of errors during the tasks). While the BESS has been used to assess other conditions and populations other than concussions it is unclear if the BESS can be used for this broader purpose. Therefore, Bell et al performed a systematic review of the reliability and validity of the BESS (included 20 articles). Intra-tester reliability (repeatability of a measure when one person does the measurements) for the total BESS score ranged from 0.60 to 0.92 (ideally this number is 0.80 or higher). Inter-tester reliability (determines if two testers will come up with similar scores) ranged from 0.57 to 0.85 (ideally this number is 0.80 or higher). Test-retest reliability (repeatability of the test over time) was moderate but one study reported that performing the BESS three times and averaging the scores provided excellent repeatability. The BESS scores were related to force-plate measures (particularly for the more challenging tasks), suggesting that the score may be a proxy for these measures. The review found that the BESS can detect differences between groups when there are large differences (concussions or fatigue) but not when the differences are more subtle. Furthermore, the BESS scores increase with age, are higher among patients with ankle instability, and improve after neuromuscular training.

This systematic review is helpful for looking at a commonly used balance assessment. The BESS can be a valuable tool for evaluating patients with suspected concussions and monitoring progression during a rehabilitation program. It’s interesting to note that while the BESS performs well (relates to similar measures and can detect noticeable differences) the reliability (repeatability) can vary greatly. This is one of the first items that the authors address in their discussion. They suggest that 1) clinicians and researchers should establish their reliability before using the BESS, 2) the same tester should be used over time to evaluate a patient, and 3) tester training can be helpful to establish consistency among multiple raters. The authors also note that performing the BESS three times and taking the average may be optimal. If you are using the BESS (or planning to) then the discussion of the article raises some helpful tips. In research, determining an evaluator’s reliability (repeatability) or agreement with another evaluator is the norm but this is often neglected in the clinical practice. This can become especially important in sports medicine clinics that have multiple clinicians evaluating the same patient over time. This may seem like a nit-picky item but performing these reliability tests (by comparing your results to another clinician or your results on multiple occasions) may lead to improved training and communication, recognition of tests that are not performing well, as well as less errors in evaluating patients. Have you ever tested how consistent you perform a particular test or how your results compare to another clinician? Try it…you might be surprised.

Written by: Jeffrey Driban


Timothy said...

Editors and posters,

I would like to congratulate you all on an excellent blog and resource to stay current on research in our field. I would like present my opinion on this article. I have not read the full meta-analysis that you describe, nor have I read the full body of literature on BESS. I have, however, clinical experience as well as experience as a concussion research technician that has led me to doubt the practical application of BESS clinically. First, I would argue that balance returns to normal before other measures and thus gives us a premature belief of return to healing demonstrate that neuroelectric indicators of dysfunction persist beyond the actual injury far more often than other indicators such as those you would measure with traditional BESS/SAC/SCAT2. (Obviously, this area requires more research to validate applicability.) Secondly, there are numerous other factors that affect balance which will make taking a baseline measurement almost requisite. This would be difficult in a clinic/hospital setting. Also, in the more traditional (for athletic trainers at least) setting, measuring balance and cognitive improvement will by definition be the opposite of physical and cognitive rest which has been shown to be the best way to resolve a concussion. Therefore, I could see repeatedly measuring BESS scores as exacerbating signs and symptoms of the concussion and, in turn, prolong recovery.
I am not going to say that BESS has absolutely no clinical relevance, however, I do think that recent research has shown that it's relevance is fading. Again, I congratulate this blog on consistently posting new material for a broad audience and bringing multiple journals into a single location.
Thank you.

Sincerely and respectfully,
Timothy Boerger - ATC

Ryan Tierney said...


Great post! I think an important aspect of this blog is the expression of opinions and people sharing their experiences. Clinicians should understand that each patient/athlete they see is a subject and how they respond to assessments and treatments should be used as data to refine clinical practice. It is as important as the research we read in journals. The BESS may be the wonderful for some, but less useful to others. I like it because it’s simple, cheap, quick, and in my experience, useful. There is some evidence using more complex instruments (e.g., virtual environments) indicating that balance may be the last to improve in some individuals. Regardless if a study says posture or memory or headaches is fastest or slowest to recover, researchers typically report group averages with individuals varying around that mean. Therefore it is important to use multifaceted approach for concussion management. One thing that is certain is that all concussions are different, but concussion is not an enigma to be afraid of. Use of a signs/symptoms checklist, neuropsychological, balance, and vestibular assessments is fairly comprehensive. Choose a tool for each based on published evidence and your experience and perform them well.

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