Two baselines are better than one: Improving the reliability of computerized testing in sports neuropsychology.

Computerized neuropsychological tests are frequently used to assist in return-to-play decisions following sports concussion. However, due to concerns about test reliability, the Centers for Disease Control and Prevention recommends yearly baseline testing. The standard practice that has developed in baseline/postinjury comparisons is to examine the difference between the most recent baseline test and postconcussion performance. Drawing from classical test theory, the present study investigated whether temporal stability could be improved by taking an alternate approach that uses the aggregate of 2 baselines to more accurately estimate baseline cognitive ability. One hundred fifteen English-speaking professional hockey players with 3 consecutive Immediate Postconcussion Assessment and Testing (ImPACT) baseline tests were extracted from a clinical program evaluation database overseen by the National Hockey League and National Hockey League Players' Association. The temporal stability of ImPACT composite scores was significantly increased by aggregating test performance during Sessions 1 and 2 to predict performance during Session 3. Using this approach, the 2-factor Memory (r = .72) and Speed (r = .79) composites of ImPACT showed acceptable long-term reliability. Using the aggregate of 2 baseline scores significantly improves temporal stability and allows for more accurate predictions of cognitive change following concussion. Clinicians are encouraged to estimate baseline abilities by taking into account all of an athlete's previous baseline scores.