Clinical Cut Point for the Postconcussion Symptom Inventory Following Adolescent Concussion

BACKGROUND: The Postconcussion Symptom Inventory (PCSI) evaluates the severity of 21 concussion-related symptoms, yielding a total symptom severity between 0 and 126. Although widely used in concussion research and care as a key element in diagnosis and management decisions, no clinically validated cut point exists to distinguish adolescents with and without a recent concussion. Therefore, the purpose of our study was to establish a PCSI cut point with adequate sensitivity, specificity, and classification accuracy for clinical use. METHODS: Adolescents within 21 days of concussion and uninjured controls completed the PCSI, and total symptom severity score was calculated. We used independent samples t tests to compare total PCSI symptom severity scores between groups, and multivariable logistic regression to calculate adjusted odds ratios (outcome = group, predictor = PCSI score, covariates = age, biological sex, concussion history, history of anxiety, and/or depression). A receiver operating characteristic (ROC) curve was used to evaluate the area under the ROC curve and determine the optimal cut point to distinguish between adolescents with and without a concussion. RESULTS: One hundred fifty-three adolescents with a concussion (15.4 ± 1.6 years; 54% female; 8.2 ± 3.6 days since injury), and 200 uninjured controls (15.8 ± 1.1 years; 84% female) were included. The concussion group had significantly higher PCSI scores than the control group (47.4 ± 26.8 vs 20.9 ± 19.4; P < 0.001). The univariable area under the ROC curve value for the PCSI to differentiate between groups was 0.80 (95% confidence interval = 0.75-0.85), and correctly classified 74% of participants as concussion or control group using a PCSI cut point of 23 (sensitivity = 68%, specificity = 83%). CONCLUSIONS: Our results suggest a PCSI cut point of 23 can distinguish between adolescents with and without a recent concussion and may provide enhanced accuracy to identify a suspected concussion in the subacute time after injury.