The Concussion Blog

On February 29th we posted about the “Cut-Off Indicator” for ImPACT(TM) and recovery periods; in that post I had some open-ended questions regarding this information/press release.  Apparently these questions were noticed by UPMC and Chuck Finder, formerly of the Post-Gazette, now part of the media relations of UPMC sent me answers.

The answers were written by Brian Lau, co-investigator of the study/paper, here are my questions and below is the actual response sent to me.

1. Why would you neurocognitive test anyone with symptoms, while still recovering?
2. Are the numbers based upon the ImPACT “norms” or a baseline calculation?
3. Is this experiment repeatable with other measures?
4. Where are the control groups?
5. Is the accuracy of ImPACT that sensitive (is there even one accurate enough to make this assessment)?
6. What did each individual do for management of the concussion in the two days?

Full unedited responses below;

1. Why would you neurocognitive test anyone with symptoms, while still recovering?
   1. The symptoms after a concussion — fatigue, headache, etc. — are non-specific findings that may or may not represent a concussion. Moreover, some athletes have some of these same symptoms at baseline. Neurocognitive testing has traditionally been used to determine the presence or absence of a concussion. This study adds to other preliminary evidence that neurocognitive testing while an athlete has symptoms during recovery may also assist in predicting length of recovery. A previous study showed that symptoms used alone had a 40.81% sensitivity in predicting protracted recovery. When neurocognitive testing was used with symptoms, the sensitivity in predicting protracted recovery increased to 65.22%.
2. Are the numbers based upon the ImPACT “norms” or a baseline calculation?
   1. There are no numbers in this study requiring the use of norms or baseline calculations. We used the numbers from the first ImPACT tests and determined cutoffs off that.
3. Is this experiment repeatable with other measures?
   1. This is the first study to attempt to set cut-offs for prognosticating return to play early after injury. As recommended in the discussion section, we hope that this study encourages other groups to conduct similar studies to evaluate the value of cut-off scores.
4. Where are the control groups?
   1. It should be noted that this was an observational study that followed athletes, whom underwent a structured recovery program. It was not designed to compare two different diagnostic modalities or treatment intervention. Therefore, the traditional control group vs. study group that compares traditional practice with a novel diagnostic tool or treatment is not represented in this study. However, recovery from a sports concussion usually takes less than 14 days. In this study, the athletes were divided into protracted and short-recovery based on this time frame. As such, the short-recovery group may be considered the control group because it represents the natural recovery time following a sports concussion.
5. Is the accuracy of ImPACT that sensitive (is there even one accurate enough to make this assessment)?
   1. ImPACT testing has been shown previously to have a high degree of sensitivity (81.9%) and specificity (89.4%) in diagnosing concussions (Shatz et al., Arch Clin Neuropsychol, 2006). The sensitivity and specificity in prognosticating the recovery time following a concussion has only recently been studied. A recent study showed that when ImPACT testing and symptoms were evaluated together, there was a sensitivity and specificity of 65.22 and 80.36%, respectively. The effectiveness of ImPACT testing as a prognosticating tool should be further validated and we hope that this study will encourage others to do so.
6. What did each individual do for management of the concussion in the two days?
   1. All athletes were followed by certified athletic trainers whom made the initial on-field diagnosis of a concussion. These certified athletic trainers were also trained in the graded extertional activity protocol used in this study which requires athletes to be symptom free at rest and to be cleared by clinical concussion specialists. Therefore, in the time frame prior to initial neurocognitive testing (mean: two days), athletes were kept out of practice and game situations.

Please respond in the comments, I am digesting the material and have passed along these answers to other colleagues in the concussion world and will be formulating a response.  In general, I thank Mr. Finder for sending their answers to me out of the blue, it was good to know that someone actually reads this.  However, even with the time and efforts of UPMC and Mr. Lau I feel these answers lead to many more questions.

1.1 – I really thought that valid baselines only stood up with no symptoms, and wouldn’t symptoms hurt reliability of the diagnostic tool?

2.1 – Going back to question 1.1, if your starting data is affected wouldn’t the remainder of the study be affected?

6.1 – I still believe that if each concussed individual did not perform the same “management techniques”, i.e. sleep, cognitive rest, school, tv, video games, etc., then this measure would be flawed.  Unless the AT’s were able to monitor for 48 hours straight there is no telling what the kids did and what they reported

Again it would be a game changer if we could find out specifics for recovery, what might be better at this time is just making the public aware that adolescent concussions will take longer than a week to recover.

PS: I do believe that Irv Muchnick will be writing about these responses, as he contacted me after I sent out this information to some colleagues.