Natalie Le Sage: Refinement and validation of a clinical decision rule integrating the use of biomarkers for early detection of persistent symptoms after a mTBI

Protocol endorsed by NCER: update 2020

New title: PoCS Rule : a clinical decision rule for early prediction of persistent symptoms after a mTBI

Introduction: Each year in Canada, the incidence of mild Traumatic Brain Injury (mTBI, cerebral concussion) is estimated at 500 cases per 100 000. Given that between 10 and 56 % of patients with mTBI will have persistent post-concussion symptoms (PPCS), there is a pressing need for emergency departments (ED) physicians and other primary care facilities to have access to a simple and reliable clinical decision rule to predict persistent symptoms after a mild traumatic brain injury (mTBI).
Main objective: To derive and validate the PoCS clinical decision Rule (Post Concussion Symptoms) for the prediction of PPCS among patients presenting to the ED after a mTBI.
Methods: This prospective cohort study took place at seven Canadian EDs. Inclusion criteria were : non-hospitalized patient aged ≥ 14 years old with a documented mTBI <24 hrs, with a GCS of ≥ 13 when evaluated in the ED. Emergency physicians identified potential participants in the ED. Relevant clinical data and blood samples were collected within 24 hours of patient arrival to the ED. The ELISA assay technique was used to dose the following biomarkers: S100B protein, NSE, C-Tau and GFAP. Research nurses conducted telephone interviews at 7, 30 and 90 days post-ED visit, in which they administered the Rivermead Post-Concussion symptoms Questionnaire (RPQ) to all included patients.The primary outcome measure was the presence of PPCS at 90 days after the mTBI. Predictive model was derived using multiple logistic regression.
Results: A total of 1333 patients were enrolled (563 for the derivation cohort and 770 for the validation cohort), of whom 15.7% had PPCS. We found no association between the four biomarkers studied and the primary outcome. The final predictive model included the following factors in ED: age, sex, headache, cervical sprain, haemorrhage on CT, TBI or psychiatric history. The one-week follow-up allowed the identification of additional risk factors such as: RPQ >21, headache, photophobia, cervical pain and physical pain to an upper or lower member. This model has a sensitivity of 94.4% (NPV=98.4%) and 91.7% (NPV=96.7%) in the derivation and validation cohorts respectively. However, the sensitivity is low: 60.5% and 49.8% respectively.
Impact on EM: The PoCS Rule will help emergency physicians to quickly identify mTBI patients at risk of PPCS and better refer them to the appropriate post-discharge resources. More research is needed in order to develop a more specific model.