Predictive Performance of Blood S100B in the Management of Patients Over 65 Years Old With Mild Traumatic Brain Injury.

BACKGROUND

We previously assessed the inclusion of S100B blood determination into clinical decision rules for mild traumatic brain injury (mTBI) management in the Emergency Department (ED) of Clermont-Ferrand Hospital. At the 0.10 µg/L threshold, S100B reduced the use of cranial computed tomography (CCT) scan in adults by at least 30% with a ~100% sensitivity. Older patients had higher serum S100B values, resulting in lower specificity (18.7%) and decreased CCT reduction. We conducted this study to confirm the age effect on S100B concentrations, and to propose new decisional thresholds for older patients.

METHODS

A total of 1172 mTBI patients aged 65 and over were included. They were divided into 3 age groups: 65-79, 80-89, and ≥ 90 years old. S100B's performance to identify intracranial lesions (sensitivity [SE] and specificity [SP]) was assessed using the routine 0.10 µg/L threshold and also other more efficient thresholds established for each age group.

RESULTS

S100B concentration medians were 0.18, 0.26, and 0.32 µg/L for the 65-79, 80-89, and ≥ 90 years old age groups, respectively (p < .001). The most efficient thresholds were 0.11 µg/L for the 65-79 age group and 0.15 µg/L for the other groups. At these new thresholds, SP was respectively 28.4%, 34.3%, and 20.5% for each age group versus 24.9%, 18.2%, and 10.5% at the 0.10 µg/L threshold.

CONCLUSIONS

Adjustment of the S100B threshold is necessary in older patients' management. An increased threshold of 0.15 µg/L is particularly interesting for patients ≥ 80 years old, allowing a significant increase of CCT scan reduction (29.3%).