Effect of β2-microglobulin in evaluating the severity and prognosis of brain injury: a clinical study

β2-microglobulin has been showing to be vital that associated with brain function and neurological diseases. This study aimed to explore the expressions of β2-microglobulin in blood and urine of the patients with brain injury, and the effect of hyperbaric oxygen therapy on the content of β2-microglobulin.

This prospective study included 54 patients with brain injury and 11 healthy controls. The patients were further assigned to two groups: the conscious disturbance group (n = 32) and the non-conscious disturbance group (n = 22) depending on the Glasgow Coma Scale (GCS). The patients received routine treatment and two courses of hyperbaric oxygen therapy (2.0ATA, 60 min, once a day, 10 days for a course). In the brain injury group, blood β2-microglobulin (β2MG) and urine β2-microglobulin (β2MU) were detected respectively before and after hyperbaric oxygen therapy (HBOT). Consciousness and cognitive scores were performed, correspondingly.

Compared with those of the control group, levels of β2MG and β2MU in the brain injury group were significantly increased before HBOT (P < 0.05). Whether it was before or after HBOT, β2MG's content in the conscious disturbance group was higher than that in the non-conscious disturbance group, while β2MU's content was obviously higher than that of the non-conscious disturbance group only before HBOT (P < 0.05). Besides, the β2MU's content in the conscious disturbance group was negatively correlated with GCS score (R = -0.351, P < 0.05) and β2MG's content in the non-conscious disturbance group was positively correlated with the MMSE score grade (R = 0.598, P < 0.05). The ROC curve was used to assess the evaluation of β2MG and β2MU for patients with impaired consciousness with the area under the curve (AUC) of β2MG and β2MU were 0.775 and 0.796, respectively.

The concentrations of blood β2-microglobulin and urinary β2-microglobulin were significantly increased in patients with brain injury. The concentrations of β2-microglobulin were correlated with the degree of consciousness and cognitive function. The changes tendency of β2-microglobulin may be considered as clinical monitoring index to evaluate the patient's disturbance of consciousness and cognitive degree, and provide a basis for early assessment of prognosis.