DOI: 10.1080/16501970500310564

Objective: To study the concurrent validity and the inter-rater reliability of the Post-Concussion Symptoms Questionnaire. Design: The approach was to study the concurrent validity of the Post-Concussion Symptoms Questionnaire when used as an interview questionnaire compared with a self-report questionnaire administered by the patients. The inter-rater reliability was also studied when 2 different raters administered the Post-Concussion Symptoms Questionnaire interview. Patients: Thirty-five patients with mild traumatic brain injury were consecutively contacted by telephone and asked whether they would be willing to participate in a follow-up intervention. Methods: The Post-Concussion Symptoms Questionnaire was completed by the patients, who answered “Yes” or “No” to the standardized questions. The patients were then interviewed to check the certain “Yes” or “No” answers, 0–10 days after having completed the first Post-Concussion Symptoms Questionnaire. The raters filled in their ratings independently. Results: The concurrent validity of answers in the questionnaire compared with those in the interview ranged from 82% to 100% agreement. The inter-rater reliability results ranged from 93% to 100% agreement between the raters. Conclusion: The Post-Concussion Symptoms Questionnaire with answers of “Yes” or “No” is a valid instrument. High reliability was found between the raters.