Coagulopathy in Traumatic Brain Injury and Its Correlation with Progressive Hemorrhagic Injury: A Systematic Review and Meta-Analysis.

The association between coagulopathy and either isolated traumatic brain injury (TBI) or progressive hemorrhagic injury (PHI) remains controversial. The aims of this study were to evaluate whether isolated TBI induces pronounced coagulopathy, in comparison with non-TBI or TBI in conjunction with other injuries (TBI + other injuries), and to examine whether there is any evidence of a relationship between coagulopathy and PHI in patients who have experienced TBI. The MEDLINE(®) and Embase databases, and the Cochrane Central Register of Controlled Trials (Central), were trawled for relevant studies. Searches covered the period from the inception of each of the databases to June 2015, and were conducted using appropriate combinations of terms and key words based on medical subject headings (MeSH). Studies were included if they compared isolated TBI with a similar severity of injury to other body regions, or compared PHI with non-PHI, with regard to coagulation tests and the prevalence of coagulopathy. We extracted the means and standard deviations (SD) of coagulation test levels, as well as their ranges or the percentage of abnormal coagulation tests, in both cases and controls. A total of 19 studies were included in our systematic review and meta-analysis. Only the mean fibrinogen (FIB) in isolated TBI was found to be significantly higher than in TBI + other injuries (pooled mean difference [MD] 32.09; 95% confidence interval [CI] 4.92-59.25; p = 0.02); in contrast, it was also significantly higher than in non-TBI (pooled MD 15.44; 95% CI 0.28-30.59; p = 0.05). We identified 15 studies that compared coagulopathy between a PHI group and a non-PHI group. The PHI group had a lower platelet count (PLT) value (pooled MD -19.21; 95% CI: -26.99 to -11.44, p < 0.001) and a higher international normalized ratio (INR) value (pooled MD 0.07; 95% CI: 0.02-0.13, p = 0.006) than the non-PHI group, but no differences were observed in the mean activated partial thromboplastin time (APTT) and prothrombin time (PT) between the PHI and non-PHI patients. In addition, PHI was significantly associated with a higher percentage of INR >1.2 (pooled OR 3.49 [95% CI 1.97-6.20], p < 0.001), PLT <100 × 109/L (pooled OR 4.74 [95% CI 2.44-9.20], p < 0.001), and coagulopathy (pooled OR 2.52; 95% CI 1.88- 3.38; p < 0.001), compared with non-PHI. The current clinical evidence does not indicate that the prevalence of coagulopathy in TBI is significantly higher than in injuries of similar severity to other areas of the body, or in multiple injuries with TBI. With respect to the association between coagulopathy and PHI, the occurrence of coagulopathy, INR, and PLT was significantly associated with PHI, but APTT and PT were not found to be associated with PHI. In the future, high quality research will be required to further characterize the effects of coagulopathy on TBI and subsequent PHI.