Trauma induced coagulopathy (TIC) is an impairment of blood clotting that occurs soon after injury and has been reported to confer a mortality rate as high as 50%. TIC is associated with increased rates of transfusion, organ failure, sepsis and longer critical care stays. Early recognition of TIC may allow trauma teams to treat coagulopathy more rapidly and may lead to improved clinical outcomes. Historically, TIC has been defined using standard laboratory coagulation tests, most commonly the prothrombin time (PT) and the PT ratio (PTr) or INR. More recently, viscoelastic tests (VHA tests) are being used with increasing frequency, favoured by clinical teams for being both point-of-care tests and for the speed with which useful results can be obtained. There is a great deal of interest in the role that VHA tests can play in the diagnosis of TIC as well as how they can be used optimally to guide transfusion therapy.
What did this paper set out to examine?
This Cochrane review set out to determine how good TEG and ROTEM assessments were at diagnosing TIC in adult trauma patients with bleeding. This was a diagnostic test accuracy review and the accuracy of the TEG and ROTEM was compared against the PTr/INR which was used as the reference standard.
What did they show?
This paper included 3 cross-sectional studies (including 430 patients in total), with civilian and military patients. No RCTs were identified. All three studies compared ROTEM to standard clotting tests and no study was specifically designed to evaluate test accuracy. The included studies focussed on a single ROTEM measure -EXTEM clot amplitude (CA) to assess TIC, but the time points that CA values were reported varied i.e. CA5, CA10 and CA15 (result at 5, 10 or 15 minutes). The reference standard that the studies used also varied with 2 studies using a PTr > 1.5 and 1 study using a PTr > 1.2.
The authors found that the 3 studies provided very little evidence on the accuracy of ROTEM and no evidence for TEG in the diagnosis of TIC. 4 domains were evaluated for risk of bias, and bias was thought to be high for two domains: (a) the choice of index test (ie ROTEM) and (b) the choice of reference standard (ie PTr/INR). The authors highlighted that this raised concerns around the interpretation of sensitivity and specificity results of the 3 studies.
What are the implications for practice and for future work?
The conclusion from this review was that there were no high quality data to confirm the accuracy of TEG or ROTEM in the diagnosis of TIC and the authors recommended that VHA tests should be limited to the research setting only.
Future research will need to focus on several areas. Interventional studies looking at the effect of ROTEM/TEG guided algorithms for diagnosis or even treatment of TIC, when compared to standard treatment without a VHA device, may be required to fully evaluate the use of these devices. However, without consensus about which VHA (or indeed standard clotting test) parameter(s) diagnose TIC the value of these interventions will be limited.
BACKGROUND Trauma-induced coagulopathy (TIC) is a disorder of the blood clotting process that occurs soon after trauma injury. A diagnosis of TIC on admission is associated with increased mortality rates, increased burdens of transfusion, greater risks of complications and longer stays in critical care. Current diagnostic testing follows local hospital processes and normally involves conventional coagulation tests including prothrombin time
ratio/international normalized ratio (PTr/INR), activated partial prothrombin time and full blood count. In some centres, thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are standard tests, but in the UK they are more commonly used in research settings. OBJECTIVES The objective was to determine the diagnostic accuracy of thromboelastography (TEG) and rotational thromboelastometry (ROTEM) for TIC in adult trauma patients with bleeding, using a reference standard of prothrombin time ratio and/or the international normalized ratio. SEARCH METHODS We ran the search on 4 March 2013. Searches ran from 1970 to current. We searched The Cochrane Library, MEDLINE (OvidSP), EMBASE Classic and EMBASE, eleven other databases, the web, and clinical trials registers. The Cochrane Injuries Group's specialised register was not searched for this review as it does not contain diagnostic test accuracy studies. We also screened reference lists, conducted forward citation searches and contacted authors. SELECTION CRITERIA We included all cross-sectional studies investigating the diagnostic test accuracy of TEG and ROTEM in patients with clinically suspected TIC, as well as case-control studies. Participants were adult trauma patients in both military and civilian settings. TIC was defined as a PTr/INR reading of 1.2 or greater, or 1.5 or greater. DATA COLLECTION AND ANALYSIS We piloted and performed all review stages in duplicate, including quality assessment using the QUADAS-2 tool, adhering to guidance in the Cochrane Handbook for Diagnostic Test Accuracy Reviews. We analysed sensitivity and specificity of included studies narratively as there were insufficient studies to perform a meta-analysis. MAIN RESULTS Three studies were included in the final analysis. All three studies used ROTEM as the test of global haemostatic function, and none of the studies used TEG. Tissue factor-activated assay EXTEM clot amplitude (CA) was the focus of the accuracy measurements in blood samples taken near to the point of admission. These CAs were not taken at a uniform time after the start of the coagulopathic trace; the time varied from five minutes, to ten minutes and fifteen minutes. The three included studies were conducted in the UK, France and Afghanistan in both civilian and military trauma settings. In two studies, median Injury Severity Scores were 12, inter-quartile range (IQR) 4 to 24; and 22, IQR 12 to 34; and in one study the median New Injury Severity Score was 34, IQR 17 to 43.There were insufficient included studies examining each of the three ROTEM CAs at 5, 10 and 15 minutes to make meta-analysis and investigation of heterogeneity valid. The results of the included studies are thus reported narratively and illustrated by a forest plot and results plotted on the receiver operating characteristic (ROC) plane.For CA5 the accuracy results were sensitivity 70% (95% CI 47% to 87%) and specificity 86% (95% CI 82% to 90%) for one study, and sensitivity 96% (95% CI 88% to 100%) and specificity 58% (95% CI 44% to 72%) for the other.For CA10 the accuracy results were sensitivity 100% (95% CI 94% to 100%) and specificity 70% (95% CI 56% to 82%).For CA15 the accuracy results were sensitivity 88% (95% CI 69% to 97%) and specificity 100% (95% CI 94% to 100%).No uninterpretable ROTEM study results were mentioned in any of the included studies.Risk of bias and concerns around applicability of findings was low across all studies for the patient and flow and timing domains. However, risk of bias and concerns around applicability of findings for the index test domain was either high or unclear