Persistent Postconcussion Symptoms: An Expert Consensus-Based Definition Using the Delphi Method.

Objective: To provide an expert consensus definition of persistent postconcussion symptoms following a mild traumatic brain injury (mTBI).

Participants: Canadian healthcare professionals caring for patients with mTBI.

Design: Online Delphi process.

Main Measures: A first Delphi round documented important dimensions or criteria to consider when defining persistent symptoms. Expert opinions were then resubmitted in 4 subsequent Delphi rounds and their relevance was rated using a 9-point Likert scale. An item with a median rating of 7 or more and a sufficient level of agreement were considered consensual.

Results: After 5 rounds, consensus was reached on a set of criteria that can be summarized as follows: presence of any symptom that cannot be attributed to a preexisting condition and that appeared within hours of an mTBI, that is still present every day 3 months after the trauma, and that has an impact on at least one sphere of a person's life.

Conclusion: This Delphi consensus proposes a set of criteria that support a more uniform definition of persistent symptoms in mild TBI among clinicians and researchers. This definition may help clinicians better identify persistent postconcussion symptoms and improve patient management.