Individual characteristics associated with youth symptom reports and persisting symptoms after concussion.

Dissonant approaches for measuring persisting symptoms after concussion (PSaC) make it difficult to predict who will experience prolonged symptoms. We sought to identify medical and sociodemographic characteristics associated with symptom burden and assess how such factors shape symptom evolution and PSaC classification after mild traumatic brain injury (mTBI). This analysis involved 1947 Post-Concussion Symptom Scale reports from 1117 youths (11-21 years): 380 with mTBI, 737 without mTBI (194 healthy non-mTBI; 543 non-mTBI with underlying medical conditions). Multivariate regressions were used to assess the relationship of symptom burden with medical and sociodemographic factors among non-mTBI youths, and interrogate how these factors impacted longitudinal symptom burden among mTBI participants. PSaC rates were characterized in the mTBI group 30 days after injury using 5 definitions: symptom burden, symptom severity, simple change in symptom burden and severity, and response to, 'What percent of normal do you feel?' In the absence of mTBI (i.e. baseline), symptom burden was associated with female sex, neuropsychiatric history, BMI and orthopaedic injury. In the 30 days following mTBI, age, sex and neuropsychiatric history were associated with symptom burden. Smaller household size, sports participation and parent education were protective. Rates of PSaC were 14.7-18.9%, displaying 84% agreement across the 5 definitions. However, PSaC misclassification was high among non-mTBI youths with underlying medical conditions (37.2-50.6%), especially with the single-item screener. Medical and sociodemographic factors affect concussion symptom reports and influence PSaC rates. A single-item screener for PSaC may be useful but risks over-detection among certain youths.