Objective: Impaired neuropsychological test performance after concussion has been used to guide restraint from play, in particular using reliable change indices (RCI). It remains unclear which of the RCI is most appropriate.
Design: Athletes were assessed prospectively before and after cerebral concussion and compared with control athletes.
Setting: Athletes were assessed in a clinical office environment after referral from a Sports Physician.
Participants: One hundred ninety-four Australian rugby league athletes were assessed preseason (time 1).
Interventions: Twenty-seven concussed athletes were assessed 2 days after trauma (time 2) and compared with 26 distribution-matched volunteer uninjured controls.
Main Outcome Measures: Cognitive performance was assessed on 5 neuropsychological measures of speed of information processing, psychomotor speed, and response inhibition. Four previously reported RCI models used in sports concussion were contrasted, as described by Barr and McCrea (2001) and Maassen et al (2006).
Results: Reliable change index models were marginally comparable in classifying the control sample. In the concussed sample, no one model seemed to be consistently more or less sensitive. Moreover, the same model could be most sensitive for one individual and least sensitive for another, even on the same test.
Conclusions: Reliable change index models can yield different outcomes regarding whether an athlete has experienced cognitive impairment after concussion. Reliable change index model sensitivity to impairment depends on multiple test and situational factors, including test-retest reliability, differences in test and retest variances, and the individual's relative position on initial testing. In the absence of consensus, the clinician must use highly reliable measures with suitably matched controls if using an RCI.