The Lancet July 03, 2010

Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage (CRASH-2): a randomised, placebo-controlled trial

CRASH-2 trial collaborators

Bottom Line

In adult trauma patients with or at risk of significant hemorrhage, the early administration of tranexamic acid safely reduced all-cause mortality and death due to bleeding without increasing the risk of thrombotic events.

Key Findings

1. All-cause mortality at 4 weeks was significantly reduced in the tranexamic acid group compared to the placebo group (14.5% vs. 16.0%; relative risk [RR] 0.91, 95% CI 0.85-0.97, p=0.0035).

2. The risk of death due to bleeding was significantly lower with tranexamic acid (4.9% vs. 5.7%; RR 0.85, 95% CI 0.76-0.96, p=0.0077).

3. There was no significant increase in fatal or non-fatal vascular occlusive events (such as deep vein thrombosis, pulmonary embolism, myocardial infarction, or stroke) between the tranexamic acid (1.7%) and placebo (2.0%) groups (p=0.084).

4. Tranexamic acid did not significantly reduce the overall proportion of patients receiving a blood product transfusion (50.4% in the TXA group vs. 51.3% in the placebo group) or the mean volume of blood transfused (6.06 vs. 6.29 units).

Study Design

Design

RCT

Double-Blind

Sample

20,211

Patients

Duration

4 wk

Median

Setting

Multicenter, 40 countries

Population Adult trauma patients presenting within 8 hours of injury with significant hemorrhage (systolic blood pressure <90 mm Hg or heart rate >110 beats/min) or considered by the clinician to be at risk for significant hemorrhage.

Intervention Tranexamic acid (1 g intravenous loading dose administered over 10 minutes, followed by an intravenous infusion of 1 g over 8 hours).

Comparator Matching placebo (0.9% saline) administered identically.

Outcome Death in hospital within 4 weeks of injury.

Study Limitations

• The pragmatic inclusion criteria ('significant hemorrhage or risk of') relied on subjective physician judgment, resulting in roughly 50% of the cohort not ultimately requiring a blood transfusion, indicating many enrolled patients did not have severe ongoing bleeding.

• The vast majority of the patient population (over 97%) was enrolled in low- to middle-income countries, raising initial questions about whether the magnitude of mortality benefit would be exactly replicated in highly advanced trauma systems in high-income countries.

• The 2010 primary paper randomized patients presenting up to 8 hours post-injury; subsequent exploratory analyses would be required to clarify that administration beyond 3 hours is actually associated with an increased risk of death due to bleeding.

Clinical Significance

CRASH-2 was a landmark, practice-changing trial demonstrating that an inexpensive and widely available drug (tranexamic acid) safely improves survival in bleeding trauma patients. This led to the rapid, global integration of TXA into both civilian and military massive transfusion and trauma protocols, and prompted its addition to the WHO Model List of Essential Medicines.

Historical Context

Before CRASH-2, antifibrinolytic agents were proven to reduce blood loss and transfusion requirements in elective major surgeries (e.g., cardiac or orthopedic surgery). However, their safety and efficacy in acute major trauma—a state characterized by a complex, dynamic coagulopathy including hyperfibrinolysis—remained unknown. The massive international success of CRASH-2 catalyzed further investigations into TXA for postpartum hemorrhage (the WOMAN trial) and traumatic brain injury (the CRASH-3 trial).

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

How does the mechanism of action of tranexamic acid specifically target the pathophysiology of trauma-induced coagulopathy without causing widespread systemic thrombosis?

Key Response

Tranexamic acid is a synthetic lysine analog that competitively inhibits the activation of plasminogen to plasmin, thereby preventing the degradation of fibrin. It stabilizes existing clots at the site of bleeding but does not inherently trigger the coagulation cascade to form new clots, explaining the CRASH-2 finding that it did not increase the incidence of vascular occlusive events.

Resident

Based on the CRASH-2 trial, what is the specific dosing and timing of tranexamic acid administration for a trauma patient, and why is adherence to this timeframe critical in the emergency department?

Key Response

The CRASH-2 protocol involves a 1g loading dose over 10 minutes followed by a 1g infusion over 8 hours. It must be administered early; subsequent analyses revealed that giving TXA within 3 hours significantly reduces mortality, but administration after 3 hours actually increases the risk of death due to bleeding.

Fellow

While CRASH-2 demonstrated a significant reduction in mortality, it did not show a reduction in blood transfusion requirements. How do you reconcile improved survival from bleeding with unchanged transfusion volumes in this specific patient population?

Key Response

The survival benefit likely results from attenuating the lethal consequences of trauma-induced coagulopathy and fibrinolysis in the microvasculature rather than solely reducing gross macroscopic hemorrhage. Furthermore, patients who survive longer due to TXA administration may continue to receive transfusions (survivorship bias), masking any potential reduction in transfusion requirements when looking at the overall cohort.

Attending

The CRASH-2 trial revolutionized trauma resuscitation, yet the absolute risk reduction in mortality was relatively small (around 1.5%). How do you contextualize this small absolute benefit to justify the widespread systemic implementation of TXA protocols in trauma systems worldwide?

Key Response

While the absolute risk reduction is modest, the Number Needed to Treat (NNT) is roughly 67. Given the extremely high global burden of severe trauma, combined with the incredibly low cost of TXA, its ease of administration, and the excellent safety profile shown in the trial, the population-level impact translates to tens of thousands of lives saved annually worldwide.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The CRASH-2 trial utilized a highly pragmatic global design with minimal exclusion criteria and an intention-to-treat analysis across 40 countries. How does this pragmatic design impact the balance between internal validity and external validity, and what statistical methods best address the heterogeneity of treatment effect?

Key Response

A pragmatic design maximizes external validity by mirroring real-world conditions across diverse healthcare settings, but it introduces noise that can dilute effect sizes and threaten internal validity. Analyzing heterogeneity of treatment effect requires interaction testing in regression models (such as examining the effect of time to treatment or baseline severity) to ensure the benefit is robust across subgroups and not driven by variations in local standard of care.

Journal Editor

As a peer reviewer evaluating the CRASH-2 manuscript, how would you critically assess the lack of standardized trauma resuscitation protocols (e.g., massive transfusion ratios) across the 274 hospitals, and does this threaten the validity of the primary mortality outcome?

Key Response

The lack of standardized background care is a common threat in multi-center global trials. However, a reviewer would note that the large-scale randomized nature of the study should theoretically distribute these variations equally between the TXA and placebo groups. The validity is maintained provided there is robust allocation concealment and baseline characteristic balance, ensuring that unmeasured local treatment confounders did not skew the mortality outcomes.

Guideline Committee

Given the CRASH-2 findings, how should major trauma guidelines grade the recommendation for early TXA administration, and how does this align with current Advanced Trauma Life Support (ATLS) and European trauma guidelines?

Key Response

The evidence supports a strong recommendation with high-quality evidence (Level 1A) for the use of TXA within 3 hours of injury. Both ATLS (10th edition) and the European guideline on management of major bleeding and coagulopathy following trauma strongly incorporate CRASH-2 findings, explicitly recommending the 1g bolus and 1g infusion protocol as the standard of care in massive hemorrhage protocols.

Clinical Landscape

Noteworthy Related Trials

2017

WOMAN Trial

n = 20,060 · Lancet

Tested

Tranexamic acid (1g IV, with a second 1g dose if needed)

Population

Women with clinically diagnosed postpartum haemorrhage

Comparator

Placebo

Endpoint

Death from all causes or hysterectomy within 42 days

Key result: Tranexamic acid significantly reduced death due to bleeding, particularly when given within 3 hours of birth, without increasing the risk of thromboembolic events.

2019

CRASH-3 Trial

n = 12,737 · Lancet

Tested

Tranexamic acid (1g loading dose, 1g infusion over 8 hours)

Population

Patients with isolated traumatic brain injury (TBI)

Comparator

Placebo

Endpoint

Head injury-related death in hospital within 28 days

Key result: Tranexamic acid reduced the risk of head injury-related death in patients with mild-to-moderate TBI when administered within 3 hours of injury, with no increase in adverse events.

2020

HALT-IT Trial

n = 12,009 · Lancet

Tested

Tranexamic acid (1g loading dose, 3g infusion over 24 hours)

Population

Patients with acute severe gastrointestinal bleeding

Comparator

Placebo

Endpoint

Death due to bleeding within 5 days

Key result: Tranexamic acid did not reduce death from gastrointestinal bleeding and was associated with a higher risk of venous thromboembolic events.

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