Amantadine for severe traumatic brain injury.

To the Editor: In their assessment of the pace of functional recovery in patients with severe traumatic brain injury who received amantadine or placebo, Giacino et al. (March 1 issue)1 report the rate of change in Disability Rating Scale (DRS) scores in both study groups, but unfortunately, they do not indicate whether their findings were associated with any minimal clinically important difference. This concept has become of increasing importance in the medical literature as clinicians and policymakers seek to verify whether the statistical significance so often shown in clinical trials actually translates into meaningful clinical improvement.2,3 Rather than focusing their study design and sample size calculations on the change in the slope of scores on the DRS, the authors may have done better to use the more clinically relevant score on the Coma Recovery Scale–Revised (CRS-R)4 as the basis of their clinical design and as a means of determining whether patients in the amantadine group crossed a threshold of minimal clinically important difference. Newer methodologies incorporating the concept of minimal clinically important difference should be encouraged in the design of future clinical trials.