The structure of post-concussion symptoms in adolescent student athletes: Confirmatory factor analysis and measurement invariance

Abstract

Objective: This study examined factor models for the Post-Concussion Symptom Scale (PCSS) at baseline and after suspected sport-related concussion, and measurement invariance from pre-injury to post-injury assessments and across age, gender, and health history groups (e.g., attention-deficit/hyperactivity disorder, psychiatric history). Methods: Adolescent student athletes (ages 13-18) completed a baseline PCSS (n = 39,015; 54.3% boys) and a subsample within 21 days of a suspected concussion (n = 1,554; 56.7% boys) completed a post-injury PCSS. Five models were evaluated for fit and invariance. Results: Confirmatory factor analyses showed good baseline and post-injury model fit for a previously supported four-factor model (i.e., cognitive-sensory, sleep-arousal, vestibular-somatic, and affective), an alternative four-factor model (i.e., cognitive, sleep-arousal, physical, and affective), and an incomplete bifactor model with vestibular-somatic and affective specific factors, along with partial invariance from pre-injury to post-injury assessments. Partial-to-full invariance was established for each model at baseline across demographic and health history groups. Conclusions: Results showed empirical and conceptual support for both PCSS subscales (i.e., cognitive, sleep-arousal, physical, and affective) and a total score for use in pre-injury to post-injury assessments and across demographic and health history groups at baseline. Future normative data, stratified by demographics and health history, could provide more precise symptom assessments for concussion management.

Keywords:

• Brain concussion
• post-concussion syndrome
• athletes
• psychometrics
• factor analysis
• statistical

Acknowledgements

The data were gathered as part of the Maine Concussion Management Initiative (MCMI) under the direction of the principal investigator Dr. Paul Berkner. The authors thank the Maine Athletic Trainers Association for their collaboration with the MCMI, and Dr. Berkner for allowing us to use the data

Disclosure statement

Grant Iverson, Ph.D. has a clinical and consulting practice in forensic neuropsychology, including expert testimony, involving individuals who have sustained mild TBIs (including athletes). He has received research funding from several test publishing companies, including ImPACT Applications, Inc., CNS Vital Signs, and Psychological Assessment Resources (PAR, Inc.). He serves as a scientific advisor for Sway Operations, LLC, Highmark, Inc., and BioDirection, Inc. He has received salary support from the Harvard Integrated Program to Protect and Improve the Health of National Football League Players Association Members, and he holds a grant as principal investigator from the National Football League. The authors do not have a commercial or proprietary interest in ImPACT^® or the Post-Concussion Symptom Scale.

Additional information

Funding

Justin E. Karr, Ph.D. acknowledges financial support from the Spaulding Research Institute Leadership Catalyst Fellowship. Grant Iverson, Ph.D. acknowledges unrestricted philanthropic support from ImPACT Applications, Inc., the Mooney-Reed Charitable Foundation, National Rugby League, and the Spaulding Research Institute.