Note:  We wrote a letter to the Editor of PLOS commenting on the McKinnes et al article (McInnes, Friesen et al. 2017).  However, the Editor does not review and publish letters in their journal.  Therefore, we have posted a summary of our letter below, and you can read the full letter with references here: McInnes- Letter to the Editor

The review by McInnes et al (McInnes, Friesen et al. 2017) and other data support the conclusion that the majority of patients with mild TBI who go to the ER have persistent neuropsychiatric symptoms.  For example, based on their scoping review of the literature, McInnes et al (McInnes, Friesen et al. 2017) found that 55% of individuals with a single mild traumatic brain injury (TBI) have chronic cognitive impairment.  The large majority of the samples they reviewed were drawn from emergency room settings.  This proportion was much higher than the often-quoted 15% rate reported in older studies (Rutherford, Merrett et al. 1979, Sterr, Herron et al. 2006 , Spinos, Sakellaropoulos et al. 2010).  Consistent with these ideas, a recent well-designed study of mild TBI patients who presented to the ED found that, one year after injury, 59% had persistent postconcussive syndrome (PCS), which includes cognitive impairment (Waljas, Iverson et al. 2015); although postconcussive symptoms are notoriously nonspecific, the rate of postconcussive syndrome was higher in mTBI patients than in normal controls.  Furthermore, several studies have found that the risk of PCS at 1 year was increased for patients who had symptoms at 1 month compared to those who did not have PCS at 1 month.  Taken together, these findings suggest that, for the important subset of patients who present to the ED, the incidence of persistent neuropsychiatric symptoms more likely than not is greater than 50%.