Sports Medicine Research: In the Lab & In the Field: Online ImPACT Test is a Valid Method of Detecting Concussions (Sports Med Res)


Friday, March 15, 2013

Online ImPACT Test is a Valid Method of Detecting Concussions

Sensitivity and specificity of the online version of ImPACT in high school and college athletes

Schatz P and Sandel N. Am J Sports Med. 2012; 41(321):321-326.

Take Home Message: The online version of the ImPACT test is a valid test for the diagnosis of concussions in high school and college athletes and may be effective for diagnosing suspected concussions when the athlete did not report symptoms.

Diagnosing sports-related concussions can be challenging and various diagnostic tools have been developed to identify sports-related concussions, including the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) tool. To date, the online version of the ImPACT test has only undergone studies to determine the test-retest reliability and rates of invalid baseline tests. Therefore, Schatz and Sandel tested the sensitivity and specificity of the online version of ImPACT using carefully matched samples of concussed and nonconcussed athletes. The data was extracted by the lead programmer at ImPACT Applications, Inc. who was blinded to the study’s hypothesis. Baseline and postconcussion data were extracted for 81 athletes with symptomatic concussions, 37 athletes with asymptomatic concussions (individuals suspected of having a concussion but who did not report their symptoms), and 81 athletes with no concussion. All athletes suspected of having a concussion were evaluated by either a certified athletic trainer or team physician. Data from athletes with symptomatic concussions were eligible for inclusion if the athlete: (a) was 13-21 years old, (b) tested within 72 hours of sustaining a concussion, (c) did not report attention deficit or hyperactivity disorder or learning disability, and (d) spoke English. Data for athletes without a concussion were included if the athlete met the criteria above except they had baseline testing at least 6 months after sustaining a concussion. The 81 athletes with concussion and symptoms were matched to 81 athletes with no recent concussions based on sex, age, handedness, sport, and history of concussion. Overall, the extracted data yielded a sensitivity and specificity of 91.4% and 69.1% respectively, and a positive and negative predictive values (the likelihood that a positive or negative test correctly identifies the present condition) of 91.4% and 69.1%. The online ImPACT test was also effective at identifying individuals suspected of sustaining a concussion, reported being asymptomatic, and had an invalid response pattern on the test (sensitivity = 97.3%, specificity = 97.3%; see definitions below).

Overall, the results indicate that the online ImPACT test is a valid test to diagnose acute concussions in high school and collegiate athletes. Studies like these are important because any time a test or outcome measure is modified it may change how the test performs. In this case, it is reassuring that the online ImPACT performs well. The probability that the test will detect a concussion if one is present (sensitivity) was 91.4%, and the probability that the test will be negative when no concussion is present (specificity) was 69.1%.  Further, the online ImPACT test detected a concussion even among athletes suspected of a concussion but did not report symptoms. In fact, the authors found that the test may perform better among the asymptomatic group and suggested that by “attempting to hide symptoms of concussion, or otherwise ‘look good’ on testing, these athletes displayed more variable behavior and paradoxically distinguished themselves” from the healthy controls. This is critical to clinicians because as education about concussions (and exposure to more professionals with diagnostic capability) increases, so too does the athlete's capability of withholding the presence of symptoms, which would allow them to be prematurely cleared to return to sport. This could result in a dangerous situation; however in these cases, the online version of the ImPACT test may be an important tool to correctly identify concussions, even in non-candid athletes. Tell us what you think. Do you currently use the online version of the ImPACT test or another tool? If another tool is used, what went into your decision to use that tool over the ImPACT test?

Written by: Kyle Harris
Reviewed by: Jeffrey Driban

Schatz P, & Sandel N (2013). Sensitivity and specificity of the online version of ImPACT in high school and collegiate athletes. The American Journal of Sports Medicine, 41 (2), 321-6 PMID: 23144368


Kristal said...

Specificity rules in, sensitivity rules out. This can be remembered by SPin and SNout. For a great resource:

Loong. Understanding sensitivity and specificity with the right side of the brain. BMJ 2003;327;716-719.

That would make this test a good test for ruling out concussions but not great on ruling in concussions except in those individuals with suspected concussions that are not reporting symptoms (the test is good at ruling in and ruling out).

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