[Application value of immature granulocyte count in predicting early infection after spinal operation]

To evaluate the early predictive value of immature granulocytes(IGs) in postoperative infection in patients with spinal injury.

The clinical data of 78 patients with spinal cord injury underwent surgery from October 2016 to October 2018 were collected. There were 57 males and 21 females, aged from 45 to 63 years old with an average of (55.2±6.1) years. The most common cause of injury was spinal trauma or degeneration. According to the American Spinal Cord Injury Association (ASIA) classification of spinal cord injury, 37 cases were complete injury(grade A and B) and 41 cases were incomplete injury (grade C and D). All the 78 patients showed different degrees of deep and shallow sensory disturbances, and underwent CT and MRI examinations after admission. According to whether the secondary infection occurred within 1 week after surgery, the patients were divided into infected group and non-infected group. At the time of admission and 1, 3, 6 days after surgery, the immature granulocyte absolute value(IG#), immature granulocyte percentage(IG%), C-reactive protein(CRP), procalcitonin(PCT), interleukin-1β(IL-1β), interleukin-6(IL-6), and tumor necrosis factor-α (TNF-α) were detected. Using ROC curve to compare the predictive value of IG%, IG#, and PCT in early detection of postoperative infection. The correlation between IG%, IG# and PCT was analyzed using the Spearman correlation test.

At a week after operation, 33 patients occurred infection and 45 patients occurred no infection(infected group and non-infected group). All patients were followed up to no serious complications and deaths at the time of discharge. The proportion of complete injury in the infected group was significantly higher than that in the non-infected group(t=3.979, P=0.046), and the cervical and thoracic vertebrae were more common in the infected group, and the non-infected group was mostly lumbar injury(t=6.226, P=0.044). One day after surgery, PCT, IG%, IG# were resectively(0.71±0.10) ng/ml, 1.08±0.10, 0.20±0.05 in infected group, while in non-infected group were(0.51±0.08) ng/ml, 0.82±0.13, 0.13±0.04, there was significant difference between two groups(P<0.001). At 3 days postoperatively, CRP, PCT, IL-6, IL-1β, TNF-α, IG%, IG# were resectively (80.47±15.74) mg/L, (2.39±0.27) ng/ml, (15.74±3.85) pg/ml, (16.47±4.75) pg/ml, (2.18±0.57) ng/ml, 0.28±0.10, 1.38±0.54 in injected group, while in non-infected group were(62.42±14.68) mg/L, (0.89±0.21) ng/ml, (13.10±3.87)pg/ml, (14.57±3.35) pg/ml, (1.63±0.37) ng/ml, 0.09±0.01, 0.83±0.24, there was significant difference between two groups(P<0.001). At 6 days postoperatively, the laboratory parameters of the infected group were significantly higher than those of the non-infected group(P<0.001). ROC curve analysis showed that PCT, IG%, and IG# could predict early infection after spinal cord injury(P<0.001), and the area under the curve (AUC) of IG# was significantly lower than PCT and IG%(respectively 0.847, 0.947, 0.934, P<0.05). Correlation analysis showed that IG%, IG# and PCT were significantly correlated, and the correlation coefficients were 0.724 and 0.472, respectively(P<0.001).

The elevated levels of IG%, IG# and PCT in patients with spinal cord injury within 24 hours after surgery have high sensitivity and specificity for predicting early secondary infection. Postoperative quantification of these indicators helps early identification of patients with high risk of infection.