Estimating the ratio of multivariate recurrent event rates with application to a blood transfusion study.
ABSTRACT: In comparative effectiveness studies of multicomponent, sequential interventions like blood product transfusion (plasma, platelets, red blood cells) for trauma and critical care patients, the timing and dynamics of treatment relative to the fragility of a patient's condition is often overlooked and underappreciated. While many hospitals have established massive transfusion protocols to ensure that physiologically optimal combinations of blood products are rapidly available, the period of time required to achieve a specified massive transfusion standard (e.g. a 1:1 or 1:2 ratio of plasma or platelets:red blood cells) has been ignored. To account for the time-varying characteristics of transfusions, we use semiparametric rate models for multivariate recurrent events to estimate blood product ratios. We use latent variables to account for multiple sources of informative censoring (early surgical or endovascular hemorrhage control procedures or death). The major advantage is that the distributions of latent variables and the dependence structure between the multivariate recurrent events and informative censoring need not be specified. Thus, our approach is robust to complex model assumptions. We establish asymptotic properties and evaluate finite sample performance through simulations, and apply the method to data from the PRospective Observational Multicenter Major Trauma Transfusion study.
Project description:The Pragmatic, Randomized Optimal Platelets and Plasma Ratios (PROPPR) trial was a randomized clinical trial comparing survival after transfusion of two different blood component ratios for emergency resuscitation of traumatic massive hemorrhage. Transfusion services supporting the study were expected to provide thawed plasma, platelets, and red blood cells within 10 minutes of request.At the 12 Level 1 trauma centers participating in PROPPR, blood components transfused and delivery times were tabulated, with a focus on universal donor (UD) plasma management. The adequacy of site plans was assessed by comparing the bedside blood availability times to study goals and the new American College of Surgeons guidelines.Eleven of 12 sites were able to consistently deliver 6 units of thawed UD plasma to their trauma-receiving unit within 10 minutes and 12 units in 20 minutes. Three sites used blood group A plasma instead of AB for massive transfusion without complications. Approximately 4700 units of plasma were given to the 680 patients enrolled in the trial. No site experienced shortages of AB plasma that limited enrollment. Two of 12 sites reported wastage of thawed AB plasma approaching 25% of AB plasma prepared.Delivering UD plasma to massively hemorrhaging patients was accomplished consistently and rapidly and without excessive wastage in high-volume trauma centers. The American College of Surgeons Trauma Quality Improvement Program guidelines for massive transfusion protocol UD plasma availability are practicable in large academic trauma centers. Use of group A plasma in trauma resuscitation needs further study.
Project description:The Netherlands Armed Forces use -80°C frozen red blood cells (RBCs), plasma and platelets combined with regular liquid stored RBCs, for the treatment of (military) casualties in Medical Treatment Facilities abroad. Our objective was to assess and compare the use of -80°C frozen blood products in combination with the different transfusion protocols and their effect on the outcome of trauma casualties.Hemovigilance and combat casualties data from Afghanistan 2006-2010 for 272 (military) trauma casualties with or without massive transfusions (MT: ?6 RBC/24hr, N = 82 and non-MT: 1-5 RBC/24hr, N = 190) were analyzed retrospectively. In November 2007, a massive transfusion protocol (MTP; 4:3:1 RBC:Plasma:Platelets) for ATLS® class III/IV hemorrhage was introduced in military theatre. Blood product use, injury severity and mortality were assessed pre- and post-introduction of the MTP. Data were compared to civilian and military trauma studies to assess effectiveness of the frozen blood products and MTP.No ABO incompatible blood products were transfused and only 1 mild transfusion reaction was observed with 3,060 transfused products. In hospital mortality decreased post-MTP for MT patients from 44% to 14% (P = 0.005) and for non-MT patients from 12.7% to 5.9% (P = 0.139). Average 24-hour RBC, plasma and platelet ratios were comparable and accompanying 24-hour mortality rates were low compared to studies that used similar numbers of liquid stored (and on site donated) blood products.This report describes for the first time that the combination of -80°C frozen platelets, plasma and red cells is safe and at least as effective as standard blood products in the treatment of (military) trauma casualties. Frozen blood can save the lives of casualties of armed conflict without the need for in-theatre blood collection. These results may also contribute to solutions for logistic problems in civilian blood supply in remote areas.
Project description:Hemorrhage remains a major cause of potentially preventable deaths. Trauma and massive transfusion are associated with coagulopathy secondary to tissue injury, hypoperfusion, dilution, and consumption of clotting factors and platelets. Concepts of damage control surgery have evolved prioritizing early control of the cause of bleeding by non-definitive means, while hemostatic control resuscitation seeks early control of coagulopathy.Hemostatic resuscitation provides transfusions with plasma and platelets in addition to red blood cells in an immediate and sustained manner as part of the transfusion protocol for massively bleeding patients. Although early and effective reversal of coagulopathy is documented, the most effective means of preventing coagulopathy of massive transfusion remains debated and randomized controlled studies are lacking. Viscoelastical whole blood assays, like TEG and ROTEM however appear advantageous for identifying coagulopathy in patients with severe hemorrhage as opposed the conventional coagulation assays.In our view, patients with uncontrolled bleeding, regardless of it's cause, should be treated with hemostatic control resuscitation involving early administration of plasma and platelets and earliest possible goal-directed, based on the results of TEG/ROTEM analysis. The aim of the goal-directed therapy should be to maintain a normal hemostatic competence until surgical hemostasis is achieved, as this appears to be associated with reduced mortality.
Project description:BACKGROUND:Up to 40% of combat casualties with a truncal injury die of massive hemorrhage before reaching a surgeon. This hemorrhage can be prevented with damage control resuscitation (DCR) methods, which are focused on replacing shed whole blood by empirically transfusing blood components in a 1:1:1:1 ratio of platelets:fresh frozen plasma:erythrocytes:cryoprecipitate (PLT:FFP:RBC:CRYO). Measurement of hemostatic function with rotational thromboelastometry (ROTEM) may allow optimization of the type and quantity of blood products transfused. Our hypothesis was that incorporating ROTEM measurements into DCR methods at the US Role 3 hospital at Bagram Airfield, Afghanistan would change the standard transfusion ratios of 1:1:1:1 to a product mix tailored specifically for the combat causality. METHODS:This retrospective study collected data from the Department of Defense Trauma Registry to compare transfusion practices and outcomes before and after ROTEM deployment to Bagram Airfield. Over the course of six months, 134 trauma patients received a transfusion (pre-ROTEM) and 85 received a transfusion and underwent ROTEM testing (post-ROTEM). Trauma teams received instruction on ROTEM use and interpretation, with no provision of a specific transfusion protocol, to supplement their clinical judgment and practice. RESULTS:The pre and post groups were not significantly different in terms of mortality, massive transfusion protocol activation, mean injury severity score, or coagulation measurements. Despite the difference in size, each group received an equal total number of transfusions. However, the post-ROTEM group received a significant increase in PLT and CRYO transfusions ratios, 4× and 2×, respectively. CONCLUSION:The introduction of ROTEM significantly improved adherence to DCR practices. The transfusion differences suggest that aggressive DCR without thromboelastometry data may result in reduced hemostatic support and underestimate the need for PLT and CRYO. Thus, future controlled trials should include ROTEM-guided coagulation management in trauma resuscitation. LEVEL OF EVIDENCE:Therapeutic, level IV.
Project description:Severely injured patients experiencing hemorrhagic shock often require massive transfusion. Earlier transfusion with higher blood product ratios (plasma, platelets, and red blood cells), defined as damage control resuscitation, has been associated with improved outcomes; however, there have been no large multicenter clinical trials.To determine the effectiveness and safety of transfusing patients with severe trauma and major bleeding using plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio.Pragmatic, phase 3, multisite, randomized clinical trial of 680 severely injured patients who arrived at 1 of 12 level I trauma centers in North America directly from the scene and were predicted to require massive transfusion between August 2012 and December 2013.Blood product ratios of 1:1:1 (338 patients) vs 1:1:2 (342 patients) during active resuscitation in addition to all local standard-of-care interventions (uncontrolled).Primary outcomes were 24-hour and 30-day all-cause mortality. Prespecified ancillary outcomes included time to hemostasis, blood product volumes transfused, complications, incidence of surgical procedures, and functional status.No significant differences were detected in mortality at 24 hours (12.7% in 1:1:1 group vs 17.0% in 1:1:2 group; difference, -4.2% [95% CI, -9.6% to 1.1%]; P?=?.12) or at 30 days (22.4% vs 26.1%, respectively; difference, -3.7% [95% CI, -10.2% to 2.7%]; P?=?.26). Exsanguination, which was the predominant cause of death within the first 24 hours, was significantly decreased in the 1:1:1 group (9.2% vs 14.6% in 1:1:2 group; difference, -5.4% [95% CI, -10.4% to -0.5%]; P?=?.03). More patients in the 1:1:1 group achieved hemostasis than in the 1:1:2 group (86% vs 78%, respectively; P?=?.006). Despite the 1:1:1 group receiving more plasma (median of 7 U vs 5 U, P?<?.001) and platelets (12 U vs 6 U, P?<?.001) and similar amounts of red blood cells (9 U) over the first 24 hours, no differences between the 2 groups were found for the 23 prespecified complications, including acute respiratory distress syndrome, multiple organ failure, venous thromboembolism, sepsis, and transfusion-related complications.Among patients with severe trauma and major bleeding, early administration of plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio did not result in significant differences in mortality at 24 hours or at 30 days. However, more patients in the 1:1:1 group achieved hemostasis and fewer experienced death due to exsanguination by 24 hours. Even though there was an increased use of plasma and platelets transfused in the 1:1:1 group, no other safety differences were identified between the 2 groups.clinicaltrials.gov Identifier: NCT01545232.
Project description:Hemostatic resuscitation has been shown to be beneficial for patients with trauma, but there is little evidence that it is equally beneficial for bleeding patients without trauma. The practice of a high transfusion ratio of fresh frozen plasma (FFP) to red blood cells (RBCs) has spread to other surgical and medical fields.To identify whether ratio-based resuscitation in patients without trauma is associated with improved survival.This study is a retrospective review of all massive transfusions provided in an urban academic hospital from January 1, 2009, through December 31, 2012. Massive transfusion was defined as the transfusion of at least 10 U of RBCs in the first 24 hours after a patient's admission to the operating room, emergency department, or intensive care unit. All patients who received massive transfusions within the study period and survived more than 30 minutes after hospital arrival were counted (n=865). Patients were grouped into those with trauma and those without trauma. Sources of data included the Research Patient Data Registry, patients' medical records, and blood bank records. All data collection occurred between April 26, 2013, and April 26, 2015. Data analysis took place from April 27, 2015, and June 22, 2016.Examination of FFP:RBC transfusion ratios for patients without trauma.There were 865 massive transfusion events that occurred within 4 years, transfusing 16?569 U of RBCs, 13?933 U of FFP, 5228 U of cryoprecipitate, and 22?635 U of platelets. Most of these transfusions were received by patients without trauma (767 [88.7%]), by men (582 [67.3%]), and for intraoperative bleeding (544 [62.9%]). The FFP:RBC ratios of survivors and nonsurvivors were nearly identical: the ratio for survivors was 1:1.5 (interquartile range [IQR], 1:1.1-1:2.2) and for nonsurvivors was 1:1.4 (IQR, 1:1.1-1:1.9; P?=?.43). Among the 767 patients without trauma, there was no difference in the adjusted odds ratio (aOR) for 30-day mortality when comparing the high FFP:RBC ratio vs the low FFP:RBC ratio subgroups (aOR, 1.10; 95% CI, 0.72-1.70; P?=?.65). In vascular surgery, the aOR for death favored the high FFP:RBC ratio subgroup (aOR,?0.16; 95% CI, 0.03-0.79; P?=?.02). However, in general surgery and medicine, the aOR for death favored the low FFP:RBC ratio subgroup; general surgery: aOR, 4.27 (95% CI, 1.28-14.22; P?=?.02); medicine: aOR, 8.48 (95% CI, 1.50-47.75; P?=?.02).High FFP:RBC transfusion ratios are applied mostly to patients without trauma, who account for nearly 90% of all massive transfusion events. Thirty-day survival was not significantly different in patients who received a high FFP:RBC ratio compared with those who received a low ratio.
Project description:PURPOSE:After damage control surgery, trauma patients are transferred to intensive care units to restore the physiology. During this period, massive transfusion might be required for ongoing bleeding and coagulopathy. This research aimed to identify predictors of massive blood transfusion in the surgical intensive care units (SICUs). METHODS:This is an analysis of the THAI-SICU study which was a prospective cohort that was done in the 9-university-based SICUs in Thailand. The study included only patients admitted due to trauma mechanisms. Massive transfusion was defined as received ≥10 units of packed red blood cells on the first day of admission. Patient characteristics and physiologic data were analyzed to identify the potential factors. A multivariable regression was then performed to identify the significant model. RESULTS:Three hundred and seventy patients were enrolled. Sixteen patients (5%) received massive transfusion in the SICUs. The factors that significantly predicted massive transfusion were an initial sequential organ failure assessment (SOFA) ≥9 (risk difference (RD) 0.13, 95% confidence interval (CI): 0.03-0.22, p = 0.01); intra-operative blood loss ≥ 4900 mL (RD 0.33, 95% CI: 0.04-0.62, p = 0.02) and intra-operative blood transfusion ≥ 10 units (RD 0.45, 95% CI: 0.06 to 0.84, p = 0.02). The probability to have massive transfusion was 0.976 in patients who had these 3 factors. CONCLUSION:Massive blood transfusion in the SICUs occurred in 5%. An initial SOFA ≥9, intra-operative blood loss ≥4900 mL, and intra-operative blood transfusion ≥10 units were the significant factors to predict massive transfusion in the SICUs.
Project description:PURPOSE:Contemporary trauma resuscitation prioritizes control of bleeding and uses major haemorrhage protocols (MHPs) to prevent and treat coagulopathy. We aimed to determine whether augmenting MHPs with Viscoelastic Haemostatic Assays (VHA) would improve outcomes compared to Conventional Coagulation Tests (CCTs). METHODS:This was a multi-centre, randomized controlled trial comparing outcomes in trauma patients who received empiric MHPs, augmented by either VHA or CCT-guided interventions. Primary outcome was the proportion of subjects who, at 24 h after injury, were alive and free of massive transfusion (10 or more red cell transfusions). Secondary outcomes included 28-day mortality. Pre-specified subgroups included patients with severe traumatic brain injury (TBI). RESULTS:Of 396 patients in the intention to treat analysis, 201 were allocated to VHA and 195 to CCT-guided therapy. At 24 h, there was no difference in the proportion of patients who were alive and free of massive transfusion (VHA: 67%, CCT: 64%, OR 1.15, 95% CI 0.76-1.73). 28-day mortality was not different overall (VHA: 25%, CCT: 28%, OR 0.84, 95% CI 0.54-1.31), nor were there differences in other secondary outcomes or serious adverse events. In pre-specified subgroups, there were no differences in primary outcomes. In the pre-specified subgroup of 74 patients with TBI, 64% were alive and free of massive transfusion at 24 h compared to 46% in the CCT arm (OR 2.12, 95% CI 0.84-5.34). CONCLUSION:There was no difference in overall outcomes between VHA- and CCT-augmented-major haemorrhage protocols.
Project description:BACKGROUND:Women are underrepresented in trauma research, and aggregated results of clinical trials may mask effects that differ by sex. It is unclear whether women respond differently to severe hemorrhage compared with men. We sought to evaluate sex-based differences in outcomes after severe trauma with hemorrhage. METHODS:We performed a secondary analysis of the Pragmatic Randomized Optimal Platelet and Plasma Ratios trial. Trauma patients predicted to require massive transfusion were randomized to a 1:1:1 vs 1:1:2 plasma to platelet to red blood cell transfusion ratio. Analysis was performed according to sex, controlling for clinical characteristics and transfusion arm. RESULTS:A total of 134 women and 546 men were analyzed. In multivariable analysis, there was no difference in mortality at 24 hours (hazard ratio for women 0.64, 95% confidence interval 0.34-1.23, P = .18) or in time to hemostasis (hazard ratio 1.10, 95% confidence interval 0.84-1.42, P = .49) by sex. We observed no difference between sexes in volume of blood products transfused during active hemorrhage. However, after anatomic hemostasis, women received lower volumes of all products, with a 38% reduction in fresh frozen plasma (mean ratio 0.62 (95% confidence interval 0.43-0.89, P = .01), 49% reduction in platelets (mean ratio 0.51, 95% confidence interval 0.33-0.79, P < .01) and 49% reduction in volume of red blood cells (mean ratio 0.51, 95% confidence interval 0.33-0.79, P < .01). CONCLUSION:Mortality and time to hemostasis of trauma patients with hemorrhage did not differ by sex. Although there was no difference in transfusion requirement during active hemorrhage, once hemostasis was achieved, women received fewer units of all blood products than men. Further research is required to determine whether women exhibit differences in coagulation during and after severe traumatic hemorrhage.