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 update 2019

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 develop persistent post-concussion symptoms (PPCS) for more than three months, there is a pressing need for physicians and nurses in the ED and other primary care facilities to have access to a simple, quick, and reliable clinical decision rule to predict complications or persistent symptoms after a mTBI. Our preliminary data have shown that predictive models solely based on clinical factors are not sufficiently accurate to identify all high-risk patients. Therefore, we tried to integrate biomarkers with clinical characteristics to develop and refine our final model called the PoCS Rule (Post Concussion Symptoms). A new prospective cohort of patients was required to validate this new model.

Objectives: The main objective of this project is to refine and validate the PoCS Rule in terms of sensitivity, specificity, PPV and NPV for the prediction of persistent symptoms after a mTBI.

Methods: Between February 21st 2017 and September 30th 2018, we recruited 770 patients at seven Canadian emergency departments to validate the final model. Inclusion criteria were: patient aged ≥ 14 years old with a documented mTBI <24 hrs, with a GCS of ≥ 13 when evaluated in the ED and non-hospitalized. Relevant clinical data as well as blood samples for biomarkers were collected. The following biomarkers were measured within 24 hours: S100B protein, NSE, C-Tau and GFAP. A standardized telephone questionnaire (Rivermead Post-Concussion symptoms Questionnaire and other validated questionnaires) was administered to all included patients at 7, 30 and 90 days after their initial visit. The primary outcome measure was the presence of persistent symptoms at 90 days after mTBI.

Results (to date): The four biomarkers used in this study were disappointing, as demonstrated by the lack of association with the primary outcome and their ROC curve. We are still working to refine and validate the PoCS Rule in order to get a more accurate model using clinical factors. Next, based on our integrated knowledge translation model, we will join forces with selected government agencies and stakeholders – Québec INESSS, Ontario Neurotrauma Foundation (ONF), etc. – in order to promote knowledge translation of the model and to plan its future implementation in practice.

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