To the Editor:
Iread with great interest the article titled “A new panel of blood biomarkers for the diagnosis of mild traumatic brain injury/concussion in adults” by Shan and colleagues, published in the January issue of the Journal of Neurotrauma.
1
I do have some questions. The key to marker discovery studies is a precise and accurate description of how the population was identified, including controls. I have significant concerns about the control population in the article. In the presentation the characteristics of the control group are unclear, described only as “not patients in the ED” and with the same exclusion criteria of the other cohorts. The challenge here is interpreting the results.
Unfortunately, the authors do not report a mean copeptin level in Table 1, so the reader must estimate the median copeptin level from Figure 1, which appears to be approximately 750 pg/mL. Prior studies report a copeptin >135 pmol/L as a strong predictor of 2-week mortality.
2
Converting pg/mL to pmol/L suggests the control population had a median copeptin level of 175.2 pmol/L. How can this possibly be a control group?
I would be interested in a more detailed description by the authors of their control group, its mean copeptin level, their explanation of these observations, and any impact this may have on their conclusions.
