Psychometric properties of self-report concussion scales and checklists

Alla S, Sullivan SJ, Hale L, McCrory P. Self-report scales/checklists for the measurement of concussion symptoms: a systematic review. Br J Sports Med. 2009;43 (suppl 1):i3-i12.

Which self-report symptom scales or checklists are psychometrically sound for clinical use to assess sport-related concussion?

Articles available in full text, published from the establishment of each database through December 2008, were identified from PubMed, Medline, CINAHL, Scopus, Web of Science, SPORTDiscus, PsycINFO, and AMED. Search terms included brain concussion, signs or symptoms, and athletic injuries, in combination with the AND Boolean operator, and were limited to studies published in English. The authors also hand searched the reference lists of retrieved articles. Additional searches of books, conference proceedings, theses, and Web sites of commercial scales were done to provide additional information about the psychometric properties and development for those scales when needed in articles meeting the inclusion criteria.

Articles were included if they identified all the items on the scale and the article was either an original research report describing the use of scales in the evaluation of concussion symptoms or a review article that discussed the use or development of concussion symptom scales. Only articles published in English and available in full text were included.

From each study, the following information was extracted by the primary author using a standardized protocol: study design, publication year, participant characteristics, reliability of the scale, and details of the scale or checklist, including name, number of items, time of measurement, format, mode of report, data analysis, scoring, and psychometric properties. A quality assessment of included studies was done using 16 items from the Downs and Black checklist1 and assessed reporting, internal validity, and external validity.

The initial database search identified 421 articles. After 131 duplicate articles were removed, 290 articles remained and were added to 17 articles found during the hand search, for a total of 307 articles; of those, 295 were available in full text. Sixty articles met the inclusion criteria and were used in the systematic review. The quality of the included studies ranged from 9 to 15 points out of a maximum quality score of 17. The included articles were published between 1995 and 2008 and included a collective total of 5864 concussed athletes and 5032 nonconcussed controls, most of whom participated in American football. The majority of the studies were descriptive studies monitoring the resolution of concussive self-report symptoms compared with either a preseason baseline or healthy control group, with a smaller number of studies (n = 8) investigating the development of a scale. The authors initially identified 20 scales that were used among the 60 included articles. Further review revealed that 14 scales were variations of the Pittsburgh Steelers postconcussion scale (the Post-Concussion Scale, Post-Concussion Scale: Revised, Post-Concussion Scale: ImPACT, Post-Concussion Symptom Scale: Vienna, Graded Symptom Checklist [GSC], Head Injury Scale, McGill ACE Post-Concussion Symptoms Scale, and CogState Sport Symptom Checklist), narrowing down to 6 core scales, which the authors discussed further. The 6 core scales were the Pittsburgh Steelers Post-Concussion Scale (17 items), Post-Concussion Symptom Assessment Questionnaire (10 items), Concussion Resolution Index postconcussion questionnaire (15 items), Signs and Symptoms Checklist (34 items), Sport Concussion Assessment Tool (SCAT) postconcussion symptom scale (25 items), and Concussion Symptom Inventory (12 items). Each of the 6 core scales includes symptoms associated with sport-related concussion; however, the number of items on each scale varied. A 7-point Likert scale was used on most scales, with a smaller number using a dichotomous (yes/no) classification. Only 7 of the 20 scales had published psychometric properties, and only 1 scale, the Concussion Symptom Inventory, was empirically driven (Rasch analysis), with development of the scale occurring before its clinical use. Internal consistency (Cronbach α) was reported for the Post-Concussion Scale (.87), Post-Concussion Scale: ImPACT 22-item (.88-.94), Head Injury Scale 9-item (.78), and Head Injury Scale 16-item (.84). Test-retest reliability has been reported only for the Post-Concussion Scale (Spearman r = .55) and the Post-Concussion Scale: ImPACT 21-item (Pearson r = .65). With respect to validity, the SCAT postconcussion scale has demonstrated face and content validity, the Post-Concussion Scale: ImPACT 22-item and Head Injury Scale 9-item have reported construct validity, and the Head Injury Scale 9-item and 16-item have published factorial validity. Sensitivity and specificity have been reported only with the GSC (0.89 and 1.0, respectively) and the Post-Concussion Scale: ImPACT 21-item when combined with the neurocognitive component of ImPACT (0.819 and 0.849, respectively). Meaningful change scores were reported for the Post-Concussion Scale (14.8 points), Post-Concussion Scale: ImPACT 22item (6.8 points), and Post-Concussion Scale: ImPACT 21-item (standard error of the difference = 7.17; 80% confidence interval = 9.18).

Numerous scales exist for measuring the number and severity of concussion-related symptoms, with most evolving from the neuropsychology literature pertaining to head-injured populations. However, very few of these were created in a systematic manner that follows scale development processes and have published psychometric properties. Clinicians need to understand these limitations when choosing and using a symptom scale for inclusion in a concussion assessment battery. Future authors should assess the underlying constructs and measurement properties of currently available scales and use the ever-increasing prospective data pools of concussed athlete information to develop scales following appropriate, systematic processes.