1 Postoperative coagulopathy in TBI patients is an important and independent factor affecting long-term survival
1.1 Patient survival
By May 26, 2019, 120 (26.8%) patients had died, 214 (47.9%) had survived, and 113 (25.3%) had been lost to follow-up. The follow-up duration was 1–53 months, and the median time was 30 months. The survival analysis showed that the 1-year survival rate was 0.690 and that the 3-year survival rate was 0.607 (Fig. 1).
1.2 Log-rank univariate analysis of TBI patient prognosis
First, TBI patient prognosis with follow-up (334 cases) was compared with log-rank univariate analysis. Table 1 summarizes the variables upon admission and perioperative coagulation. According to the log-rank univariate analysis, the following factors were considered to be significantly associated with the survival of patients suffering from TBI: age (45–60 y, P = 0.015; >60 y, P < 0.001), AIS (head) = 5 (P < 0.001), GCS ≤ 8 (P < 0.001), abnormal pupil reaction (P < 0.001), systolic pressure at admission < 90 mmHg (P = 0.004), GLU > 151 mg/dL (P = 0.003), AST ≥ 40U/L (P = 0.049), K+ <3.5 mmol/L or > 5.5 mmol/L (P = 0,048), and postoperative coagulopathy (P = 0.007). The number of TBI patients < 45, 45–60, and > 60 was 87 (26.0%), 154 (46.1%), 93 (27.9%), respectively. In the group of patients < 45 years old, 17 (19.5%) died, while 70 (80.1%) survived. In the group of patients aged 45–60 years, 53 (34.4%) died, while 101 (65.6%) survived. In the group of patients > 60 years old, 50 (53.8%) died, while 43 (46.2%) survived. In terms of the severity of traumatic brain injury patients, which was based on the GCS score and AIS (head), the number of GCS ≤ 8 were 97 (80.3%) in died group and 93 (43.5%) in survival group, respectively, while the number of AIS (head) = 5 were 83 (69.2%) in the death group and 64 (30.0%) in the survival group. A total of 112 (93.3%) TBI patients had abnormal pupil reactions in the death group, and 153 (71.5%) TBI patients had abnormal pupil reactions in the survival group. Ten patients had a systolic pressure < 90 mmHg at admission, and seven of these 10 patients died. In the death group, 91 (75.8%), 90 (75.0%) and 77 (64.2%) patients had abnormal glucose, ALT and K+ levels, respectively, in contrast to 124 (57.9%), 117 (54.7%) and 114 (53.3%) patients who had abnormal glucose, ALT and K+ levels in the survival group. Interestingly, compared to preoperative coagulopathy, postoperative coagulopathy occurred in 75 of these 120 patients who died and 100 of these 214 patients who survived. However, there was no statistically significant difference in gender, midline shift, subarachnoid hemorrhage, multiple injury, GB, AST, BUN, Na+, CI−, Ca2+, RBC, or preoperative coagulopathy between the death and survival groups, as shown in Table 1.
1.3 Cox regression model analysis for the influencing factors for TBI patient prognosis
Next, variables that were statistically significant according to the univariate analysis were analyzed using a Cox regression model. Multivariate Cox regression analysis identified age, AIS(head) = 5, GCS ≤ 8, admission systolic pressure < 90 mmHg and postoperative coagulopathy as independent risk factors for survival following TBI (Table 2).
Interestingly, the postoperative coagulopathy was an independent risk factor, as we theoretically inferred. The 1-year survival rate of TBI patients suffering from postoperative coagulopathy was 0.625, and the 3-year survival rate was 0.558. Accordingly, the 1-year survival rate of TBI patients without postoperative coagulation dysfunction was 0.762 and the 3-year survival rate was 0.683. (Fig. 2)
2 Risk factors for postoperative coagulopathy in TBI patients
2.1 Patient Demographics
In this section, we explored which factors contributed to postoperative coagulopathy. In total, 447 patients were admitted for further analysis, and 215 patients had postoperative coagulopathy. Table 3 lists the differences in variables at admission between patients with postoperative coagulopathy and those without postoperative coagulopathy. The severity of traumatic brain injury in patients based on AIS(head) and GCS scores was statistically significant. The number of patients with AIS(head) = 5 was 198 TBI patients, and postoperative coagulopathy occurred in 115 of these 198 patients. The number of patients with a GCS score ≤ 8 was 248 TBI patients, and postoperative coagulopathy appeared in 145 of these 248 TBI patients. A total of 196 (84.5%) patients had abnormal pupil reactions in non-postoperative coagulopathy group, while 163 (75.8%) cases in postoperative coagulopathy group. The presence of multiple injury was also statistically significant (P = 0.006). Postoperative coagulopathy occurred in 98(60.5%) of these 162 patients with multiple injury. Patient biochemical tests upon admission, including hemoglobin (P = 0.001), ALT (P = 0.001), AST (P < 0.001) and RBC (P < 0.001) were also statistically significant. Other variables were not statistically significant, as shown in Table 3.
2.2 Perioperative Characteristics
The differences in perioperative variables between the postoperative coagulopathy and non-postoperative coagulopathy groups are shown in Table 4. Eighty-four TBI patients were diagnosed with coagulopathy preoperatively, of whom 65 (77.4%) had postoperative coagulopathy. Only moderate and severe shock were statistically significant (P = 0.038). Crystalloid solution > 2900 mL or Colloidal solution > 1100 mL was statistically significant (P = 0.014, P < 0.001, respectively). The infusion of crystalloid and colloidal solutions, which amounted to more than 3450 mL, was a risk factor(P < 0.001), with a total of 167 patients. A total of 108 (64.7%) of these 167 patients had postoperative coagulopathy. Similarly, net-fluid-input > 2425 mL was statistically significant (P = 0.001). In the non-postoperative coagulopathy group, intraoperative bleeding exceeded 950 mL in 87 (40.5%) patients, and in 154 (66.4%) patients in the postoperative coagulopathy group (P < 0.001). A total of 306 TBI patients received decompressive craniectomy, 175 of these 306 cases had postoperative coagulopathy (P < 0.001). The total surgery time, which was more than 3.225 hours, was statistically significant (P = 0.017).
2.3 Multivariate logistic regression analysis of postoperative coagulopathy in TBI patients
Next, we used a forward stepwise binary logistic regression model to examine the statistically significant factors in the univariate analysis. The statistically significant factors after logistic regression are shown in Table 5. Multivariate analysis identified abnormal ALT (P = 0.003) and RBC (P < 0.001) at admission, preoperative coagulopathy (P < 0.001), infusion of colloidal solution more than 1100 mL (P < 0.001), and intraoperative bleeding > 950 mL (P < 0.001) as independent risk factors for postoperative coagulation following TBI (Table 5).