Sports Medicine Research: In the Lab & In the Field: Is Normative Data the New Normal? (Sports Med Res)


Monday, December 5, 2016

Is Normative Data the New Normal?

Normative Values of the Sport Concussion Assessment Tool (SCAT3) in High School Athletes

Snedden TR, Brooks MA, Hetzel S, McGuine T. Clinical Journal of Sports Medicine. 2016: Sep.

Take Home Message: Individual differences may be seen in baseline SCAT3 data between sex, history of concussion, and history of comorbidities. Therefore, using the patient’s personal medical history may add value to the SCAT3 sideline screening.

One of the most common assessment tools utilized to screen for a concussion is the sport concussion assessment tool (SCAT). Previous authors established that baseline testing utilizing the SCAT2 version found scores varied depending on specific modifying factors (age, sex, concussion history). The updated SCAT3 was released; however, there has been little research done to establish if these modifying factors exist in the current version. Therefore, the authors evaluated baseline SCAT3 scores from 750 healthy, nonconcussed high school athletes from 7 Wisconsin high schools (571 male; ~15 years of age) to establish normative data to account for sex, age and concussion history differences. Athletic trainers administered the tool prior to the start of each athlete’s respective season in a cafeteria or gymnasium. Two SCAT3 assessments (Maddocks questions and Tandem Gait) were not assessed as they were either out of place in the baseline setting or participating athletic trainers suggested they would not use this portion of the test during the sideline assessment. The authors found that males reported higher baseline symptoms and symptom severity scores compared to females, and females scored better on the SAC and orientation scores than males. Additionally, athletes who self-reported a history of concussions, headaches, migraines, learning disability, dyslexia, attention deficit disorder/ attention deficit hyperactivity disorder (ADD/ADHD) or depression/anxiety reported higher baseline symptoms and severity scores. Athletes with a history of concussion did not perform differently on the SAC portion of the SCAT3 compared to those without a history, but all of the other previously mentioned modifiers showed worse performance. Athletes who self-reported a history of concussion, diagnosis of a learning disability, dyslexia or ADD/ADHD scored more errors on the balance error scoring system (BESS) than those who did not. Age was not a modifying factor on any of the SCAT3 sections.

This was an important study because it was the first to evaluate the potential modifying factors for SCAT3 baseline testing. Despite the presence of several statistically significant findings, there were limited clinically significant findings associated with each modifying factor and SCAT3 performance. An interesting result of the current study was that athletes who self-reported a learning disability scored worse on the BESS portion of the SCAT3. Similarly, the increased symptom reporting by males (vs. females) does not align well with previously reported sex differences. It should be noted that the SCAT3, like any test, has limitations, which may limit certain uses in clinical practice. The SAC has been observed to have ceiling effects, which can sometimes make interpretation convoluted. In clinical practice, these limitations are sometimes mitigated by athletic trainers modifying the way the SCAT3 is administered to make it more difficult. Therefore, when a clinician is creating a normative database, it is important to consider using those particular administration techniques, which are going to be upheld during the post-injury assessment. It is not recommended and caution is warranted when administering any test outside of the provided instructions given that measurement properties such as reliability and validity are based on those instructions. Individualized school/institution specific normative data would not only limit variability in administration techniques, but also decrease the uncertainty about how one institution’s athletes compare to national normative values. As was seen in this study, differences are likely to appear between subgroups such as sex and those with and without modifying factors. Therefore clinicians should be aware of how their athlete population performs and should use caution when utilizing normative data that was collected outside of that population.

Questions for Discussion: Do you use normative data or baseline data to evaluate your athletes’ concussions? If so, whose normative data should you use?

Written by: Sam Walton, MEd, ATC
Reviewed by: Jane McDevitt

Related Posts:

Snedden TR, Brooks MA, Hetzel S, & McGuine T (2016). Normative Values of the Sport Concussion Assessment Tool 3 (SCAT3) in High School Athletes. Clinical journal of sport medicine PMID: 27606952


Landon Lempke, ATC said...

In regards to the study, I think this study overall did a great job of collecting normative data and assess the new SCAT 3 with a large sample size. With any study though there are limitations and concerns. The use of gymnasiums/cafeterias to administer the SCAT 3 is a concern for me since these tests are designed to be completed in a quiet individual setting, but at the same time this is also how high school settings have to do baseline data collection due to a lack of assistance. Additionally, the athletic trainers chose not to complete the tandem gait or maddocks questions because they would not be using them clinically. If I remember correctly there is some research out there showing that the tandem gait task is a moderately reliable and clinically important tool when assessing for concussions. To not collect baseline data on this is something I wish was completed.

I believe the idea of using normative data is a valuable tool, but we need to remember that the patient is an individual. Comparing an athlete’s baseline scores to normative data can be beneficial and will likely show where they deviate from the average individual with similar demographics. That being said, if you do not baseline an individual and compare their results to the normative values there is likely an inherited risk for inaccuracy due to this. That individual could have in general low neurocognitive scores compared to peers. I believe that utilizing baseline examinations in addition to normative data allows you to be more precise and see a better “picture” of what might be going on.

To address your initial question Sam, I currently use both baseline and normative data collected for our neurocognitive test (imPACT) but I do not use normative or baseline data for the SCAT 3. This is something I wish was completed prior to the start of each season, but unfortunately it has not been implemented.

Jeffrey Driban said...

Landon, thanks for the comment. I also am always a little hesitant about normative data b/c if the patient has one thing that affects their testing (e.g., certain medications, ADHD) then the normative data may throw us off. I like how you are using both baseline and normative data. Thanks again for the comment.

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