[An investigation on correlation of severity of brain injury with the expression of activin A and C-reactive protein].

OBJECTIVE

To determine the dynamic change in serum levels of activin A (ACTA) and C-reaction protein (CRP) in patients with brain injury, and to investigate its significance.

METHODS

A prospective study was conducted. A total of 57 adult patients with brain injury occurring within 24 hours admitted to intensive care unit (ICU) of the First Affiliated Hospital of Zhengzhou University from August 2012 to June 2013 were enrolled. The patients were allocated into three groups according to their Glasgow coma scale (GCS) as follows: minor brain injury (GCS 13-15, n=17), moderate brain injury (GCS 9-12, n=18), heavy brain injury (GCS 3-8, n=22). The clinical and related laboratory data (reflecting the function of liver, kidney, lung, blood coagulability etc.) were recorded after ICU admission. At the same time, venous samples were collected on the day 1, 2, 3, 5, 7 after ICU admission for determination of ACTA with enzyme linked immunosorbent assay (ELISA) and CRP with fluorescence immunoassay technology. The correlation between ACTA and CRP was analyzed by linear correlation. The receiver operating characteristic (ROC) curve was plotted to analyze the accuracy of ACTA and CRP as a prognostic indicator in brain injury. Fifteen healthy persons were enrolled as the control group.

RESULTS

The serum levels of ACTA and CRP in patients with minor, moderate and heavy brain injury were significantly higher than those in healthy control group [ACTA (μg/L): 23.96±3.55, 42.06±5.67, 52.32±4.46 vs. 13.66±2.45, all P<0.01; CRP (mg/L): 14.12±2.45, 23.05±2.85, 30.93±2.35 vs. 3.42±2.25, all P<0.01]. As the patients' condition worsening, levels of ACTA and CRP tended to elevate (all P<0.01). Levels of ACTA and CRP in minor, moderate and heavy brain injury groups were increased after ICU admission. On day 3, levels of serum ACTA and CRP reached the peak values [ACTA (μg/L):30.62±2.54, 51.35±2.55, 60.52±2.55; CRP (mg/L): 18.62±2.64, 30.35±2.25, 37.52±2.55], and then they lowered gradually. In minor and moderate brain injury groups, the levels of ACTA and CRP were slowly descending, and on day 7, they maintained at a lower level [ACTA (μg/L): 13.68±2.54, 37.74±2.55; CRP (mg/L): 6.68±2.44, 19.74±2.55]. On the contrary, the levels of ACTA and CRP in heavy brain injury group persistently maintained at a high level on day 7 [ACTA: (42.32±2.54) μg/L, CRP: (33.32±2.56) mg/L]. There were significant differences in ACTA and CRP among different degrees of brain injury groups (all P<0.01). There was a positive correlation between ACTA and CRP (r=0.958, P=0.007). ROC curve analysis showed that the sensitivity for brain injury prediction was 93.3% for ACTA with specificity 95.0%, area under ROC curve(AUC) 0.843, and the sensitivity for CRP was 89.1% with specificity 68.2%, AUC 0.723.

CONCLUSIONS

Serum levels of ACTA and CRP in patients with brain injury are strongly correlated with the severity of the injury. Furthermore, ACTA is more sensitive than CRP in detecting early brain injury. Therefore, ACTA is a specific factor for detecting brain injury.