Expanding the understanding of disability in persons with traumatic brain injury.

Neurology 2012;78:1454–1455 Progress in treating acute, critical, and often fatal brain injury has been substantial. Prior to modern emergent medical and neurosurgical care, patients with moderate to severe traumatic brain injury (TBI) often did not survive.1 Now, they do and the result is a growing “silent epidemic.”2 The Centers for Disease Control and Prevention (CDC)’s conservative estimate of the annual incidence of TBI is 1.7 million and TBI is the “signature” injury of the Iraq and Afghanistan wars, where estimates range as high as 300,000.3 At least 5 years postinjury, more than half of patients may remain disabled.4 This issue of Neurology adds to our understanding of this disability. The most comprehensive investigation of decisionmaking capacity in TBI patients shows that across all levels of severity, survivors of TBI have impaired ability to make medical decisions.5 Triebel et al.5 examined medical decision-making capacity (MDC) in TBI patients at approximately 1 month postinjury using a well-validated instrument, the Capacity to Consent to Treatment Instrument. The instrument measures the 4 decisional abilities— understanding, reasoning, appreciation, and choice—in the context of information disclosed in 2 medical decision vignettes. Collectively, these abilities constitute decision-making capacity. Of particular value, patients’ scores on these decisional abilities were compared to a comparator group of non-brain-injured and cognitively normal adults. The researchers used 2 analytic techniques to examine how patients performed on each of the measures of decision-making ability. They compared the TBI group’s ability scores to the performance of the other group, and for each ability measure, they classified patients’ scores into ranges of impairment (none, mild/moderate, or severe impairment), based on standard deviations from the scores of cognitively normal adults. Patients with moderate to severe TBI have the highest likelihood for residual cognitive impairment and thus expected MDC impairments. It is no surprise that Triebel et al. document capacity impairment in up to 80% of these patients. The high levels of disability associated with moderate to severe TBI, along with the fact that these injuries disproportionately occur in individuals 35 and younger, indicates a significant need for clinical research to improve treatment outcomes that extend into the subacute to chronic stage; decision-making capacity could serve as a clinically relevant outcome measure. The results from less impaired patients illustrate how even mild forms of TBI (mTBI) are clinically important. By definition, these patients have experienced either no or only brief loss of consciousness. Even within the first month, cognitive sequelae tend to be minimal. The untested assumption was that all mTBI patients would have adequate MDC because of the mildness of the injury. The study by Triebel et al.5 shows otherwise. As a group, mTBI patients performed as well as controls, but when analyzed as individuals, between 10% and 30% had ability scores in the ranges of mild to severe impairment. The finding is important. Triebel et al. suggest the need for better ascertainment of TBI, including those with mTBI who would not necessarily be suspect for reduced capacity, especially since mTBIs are the most common of all brain injuries. CDC statistics likely underestimate the true incidence of mTBI because they are based on recorded emergency medical and hospital admission records. Others have examined clinic and office records within a health care system, finding higher rates,6 with 70%–90% of all TBIs being in the mild range of injury. By examining TBI subjects on a continuum of injury severity, Triebel et al. demonstrated that injury severity directly related to MDC. Between mTBI and moderate to severe TBI are patients with mild but complicated TBI, or mcTBI. These are patients with mTBI by Glasgow Coma Scale standards of a score of 13–15 but positive neuroimaging. Impaired decisional abilities were found in 50% of