Concussion symptom inventory: an empirically derived scale for monitoring resolution of symptoms following sport-related concussion

Abstract

Self-report post-concussion symptom scales have been a key method for monitoring recovery from sport-related concussion, to assist in medical management, and return-to-play decision-making. To date, however, item selection and scaling metrics for these instruments have been based solely upon clinical judgment, and no one scale has been identified as the "gold standard". We analyzed a large set of data from existing scales obtained from three separate case-control studies in order to derive a sensitive and efficient scale for this application by eliminating items that were found to be insensitive to concussion. Baseline data from symptom checklists including a total of 27 symptom variables were collected from a total of 16,350 high school and college athletes. Follow-up data were obtained from 641 athletes who subsequently incurred a concussion. Symptom checklists were administered at baseline (preseason), immediately post-concussion, post-game, and at 1, 3, and 5 days post-injury. Effect-size analyses resulted in the retention of only 12 of the 27 variables. Receiver-operating characteristic analyses were used to confirm that the reduction in items did not reduce sensitivity or specificity. The newly derived Concussion Symptom Inventory is presented and recommended as a research and clinical tool for monitoring recovery from sport-related concussion.

Figures

Fig. 1.

Receiver-operating characteristic curves comparing the newly derived 12-item Concussion Symptom Inventory (CSI) scale to the full scale (abbreviated GSC for Graded Symptom Checklist). Baseline scores for the entire sample were compared with scores immediately post injury for the 641 concussed athletes. There is virtually complete overlap between the scales, suggesting that the 12-item CSI is as effective as the full GSC in detecting the effects of concussion at this time point.

Fig. 2.

Receiver-operating characteristic curves comparing the newly derived 12-item Concussion Symptom Inventory (CSI) scale to the full scale (abbreviated GSC for Graded Symptom Checklist). Baseline scores for the entire sample were compared with scores at Day 5 post injury for the 41 concussed athletes. Although discriminability is reduced compared with the immediate post-injury assessment for both scales, they are again comparable in terms of area under the curve (see text), suggesting that the 12-item CSI is as effective as the full GSC in detecting the effects of concussion at this time point.

Fig. 3.

Mean Concussion Symptom Inventory (CSI) scores for the 641 concussed athletes at baseline and post-injury assessments. Asterisk (*) indicates significant difference from baseline on matched-pair t-tests (see Table 2 for additional descriptive statistics).