Does Early Administration of Tranexamic Acid Reduce Blood Loss and Perioperative Transfusion Requirement: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Does Early Administration of Tranexamic Acid Reduce Blood Loss and Perioperative Transfusion Requirement (NCT03182751), a randomized phase 2 study. The primary outcome is Number of Subjects Transfused at Least 1 Unit of Packed Red Blood Cells.

2. Clinical Question

The clinical question is framed around a specific event during the hospital stay: whether a participant received at least one unit of packed red blood cells. Transfusion decisions were to be considered for patients with hemoglobin below 8 g/dL when persistent symptoms or a history of significant cardiac disease could limit compensation for anemia. Transfusion was also to be considered for patients with hemoglobin below 7 g/dL regardless of symptoms. These criteria help define the context in which the endpoint was assessed, but the registry record does not provide individual hemoglobin values or the reasons for each transfusion.

The trial also registered outcomes related to the number of units transfused, calculated blood loss, symptomatic venous thromboembolism, wound complications, myocardial infarction, cerebrovascular accident, and all-cause mortality. Those outcomes address different dimensions of the study question. They should not be treated as interchangeable with the primary endpoint: a participant can have a particular amount of calculated blood loss without receiving a transfusion, and the primary endpoint records whether a transfusion occurred rather than its volume or cause.

3. Trial Design

The registry describes a phase 2, randomized, quadruple-masked, parallel-group trial sponsored by Mayo Clinic. The trial status is completed. Enrollment was 128, with 64 participants reported in the tranexamic acid arm and 64 in the control arm. The registry dates the study start as 2018-04-02 and primary completion as 2022-05-24. These are registry-recorded study dates; they do not establish when each participant was enrolled or followed.

Participants in the tranexamic acid arm were treated with early administration of TXA in the Emergency Department. Participants in the control arm received placebo in the Emergency Department. Randomization is recorded, but the method used to generate or conceal the allocation sequence is not reported in the registry record. Quadruple masking is recorded, but the registry information presented does not specify which groups of people were masked or how masking was maintained.

The primary endpoint was assessed over the length of hospitalization, described as approximately 3 to 5 days. The endpoint was the number of participants transfused with at least one unit of packed red blood cells. The registry also describes secondary outcomes with different timeframes: the number of units transfused and calculated blood loss over hospitalization, and symptomatic venous thromboembolism within 6 months of surgery. The registry lists additional outcomes, including wound complications, myocardial infarction, cerebrovascular accident, and all-cause mortality.

The design information establishes the assigned comparison and broad masking structure, but it does not report the trial’s original sample-size justification, detailed statistical analysis plan, interim analysis procedures, or analysis populations. Those omissions limit what can be inferred about how the trial was planned and how the posted summaries relate to any prespecified analysis.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number of Subjects Transfused at Least 1 Unit of Packed Red Blood Cells, measured over Length of hospitalization (approximately 3 to 5 days).

The primary endpoint counts participants who received at least one unit of packed red blood cells during hospitalization. It is a binary participant-level outcome: each participant either met the endpoint or did not. The reported arm counts are 17 participants in the tranexamic acid arm and 19 in the control arm, with 64 participants in each arm.

This endpoint is used to capture whether transfusion occurred, rather than the amount of blood lost or the number of units given. That makes it a direct summary of a clinically consequential care event during the hospital stay. The transfusion criteria in the registry provide context for this event: transfusion was to be 8 g/dL when persistent symptoms or significant cardiac history were present, and below 7 g/dL regardless of symptoms. The record does not report how often each criterion was met or how clinicians applied them for individual participants.

Because the endpoint is a count of participants with an event, the main comparison can be expressed as a difference in event proportions between arms. The registry’s posted effect estimate is a risk difference, with the tranexamic acid arm compared with control. A negative estimate indicates fewer transfused participants in the tranexamic acid arm in this comparison. The endpoint does not, by itself, describe transfusion quantity, total calculated blood loss, complications, or outcomes after hospitalization.

7. Results Posted in the Registry

• Tranexamic Acid Arm (TXA): 26.6% (17/64) versus 29.7% (19/64) on control; risk difference -3.1 percentage points (95% CI -18.7 to 12.4), risk ratio 0.89 (0.51–1.56); unadjusted two-proportion z-test p = 0.694.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Number of Units of Packed Red Blood Cells Transfused

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Tranexamic Acid Arm (TXA): mean 1.90 versus 2.30 on control; difference -0.40 (95% CI -1.58 to 0.78), standardized effect d = -0.22; z-test p = 0.508.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tranexamic Acid Arm (TXA) and the control. The interval gives the range of effects that remain compatible with the data.

Calculated Blood Loss

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Tranexamic Acid Arm (TXA): mean 1,600 versus 2,000 on control; difference -400.00 (95% CI -851.75 to 51.75), standardized effect d = -0.31; z-test p = 0.083.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tranexamic Acid Arm (TXA) and the control. The interval gives the range of effects that remain compatible with the data.

Number of Subjects to Experience Symptomatic Venous Thromboembolism (VTE)

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Tranexamic Acid Arm (TXA): 4.7% (3/64) versus 1.6% (1/64) on control; risk difference 3.1 percentage points (95% CI -2.9 to 9.1), risk ratio 3.00 (0.32–28.08); unadjusted two-proportion z-test p = 0.310.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tranexamic Acid Arm (TXA) and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the interpretation beyond the primary transfusion event. They include transfusion quantity, calculated blood loss, symptomatic venous thromboembolism, and other outcomes listed in the registry, including wound complications, myocardial infarction, cerebrovascular accident, and all-cause mortality. The posted numerical comparisons for transfusion quantity, calculated blood loss, and symptomatic venous thromboembolism address distinct questions and use different outcome scales.

Across the numerical comparisons, the point estimates do not all point in the same direction. The primary transfusion endpoint and calculated blood loss have estimates lower in the TXA arm, while the symptomatic VTE estimate is higher in that arm. The confidence intervals for these comparisons include no difference. This pattern does not establish a consistent effect across outcomes, and the different measures should not be combined as if they were one endpoint.

These secondary outcomes can help describe the range of outcomes observed, but they do not replace the primary endpoint. The secondary comparisons are unadjusted, and the registry record does not report a multiplicity strategy or a hierarchy for interpreting them. When many outcomes are examined, the chance of at least one apparently unusual result can increase even if no real differences exist. For that reason, unadjusted secondary findings generally carry less evidential weight than a prespecified primary comparison, particularly when event counts are limited.

The registry lists additional secondary outcomes, but detailed comparative analyses for every listed outcome are not reported in the registry record. Results for one secondary outcome should not be used to infer an unreported result for another. Overall, the secondary information is best read as descriptive context around the primary comparison, with uncertainty and multiplicity in mind rather than as independent confirmation.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Units of Packed Red Blood Cells Transfused
• Calculated Blood Loss
• Number of Subjects to Experience Symptomatic Venous Thromboembolism (VTE)
• Wound Complications
• (Myocardial Infarction) MI Diagnosed
• Cerebrovascular Accident (CVA) Diagnosed
• All-cause Mortality

9. Statistical Interpretation

10. Statistical Methods Explained

What does randomization contribute?

In general, random assignment is intended to make the treatment groups comparable on average with respect to both measured and unmeasured characteristics. This can support a causal comparison when allocation is implemented as planned and outcome data are handled appropriately. Randomization does not guarantee that the groups will be identical, especially in a study of this size, and it does not remove the need to examine uncertainty, missing data, or deviations from the planned analysis. The registry record confirms randomization but does not report the sequence-generation or allocation-concealment methods.

What does masking contribute?

In general, masking is intended to reduce the possibility that knowledge of assigned treatment influences care, outcome assessment, or reporting. The registry records quadruple masking. It does not identify the masked roles or describe the procedures used to preserve masking, so those details cannot be evaluated from the registry record.

How should the risk difference be read?

The primary endpoint and the symptomatic venous thromboembolism outcome are counts of participants with an event. For these binary outcomes, a risk difference compares the event proportions in the two arms. The contrast is oriented as tranexamic acid minus control in the posted comparisons. A negative risk difference means the event proportion was lower in the TXA arm in the observed data; a positive value means it was higher. The primary risk difference is -0.031, while the symptomatic venous thromboembolism risk difference is 0.031. These are estimates, not exact measurements of a treatment effect in every possible population.

A confidence interval expresses statistical uncertainty around an estimate under the analysis assumptions. When an interval includes zero for a difference, the data are compatible with no difference as well as with values on either side of zero within the interval. The interval does not assign probabilities to particular effects, and it does not capture every source of uncertainty, such as bias from missing data or limitations in outcome measurement.

How should mean differences be read?

The number of units transfused and calculated blood loss are summarized as means and standard deviations. A mean difference compares the arm means, again with TXA minus control in the posted comparisons. A negative mean difference indicates a lower observed mean in the TXA arm. The units outcome has a reported mean difference of -0.4 units; calculated blood loss has a reported mean difference of -400.0 mL.

Standard deviation describes variability among individual observations around an arm mean. It is not the same as the standard error, which describes the precision of an estimated mean. More variability can make a comparison less precise when the available sample size is fixed. In general, if outcome variability differs substantially across groups or if a continuous outcome has a markedly skewed distribution, a simple mean-based summary may not fully describe the data. Distributional details and any alternative analyses are not reported in the registry record.

Why are unadjusted p-values limited?

A p-value is calculated relative to a statistical model and a null hypothesis, commonly no difference between arms. An unadjusted p-value does not account for testing multiple outcomes or comparisons. A value above a conventional threshold is not proof of no effect, and a value below a threshold would not, by itself, establish importance or freedom from bias. The posted p-values for the primary and secondary comparisons are unadjusted. The registry record does not report a multiplicity adjustment or a sponsor analysis that would clarify how these tests were prioritized.

What are the planning illustrations?

The sample-size illustrations use the observed effect as a starting point and show planning for stated fractions of that effect. The stated assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. For the non-time-to-event outcomes, the figures are participants per arm. These calculations are planning illustrations, not the original trial’s design justification. Their purpose is to show how much larger a future study might need to be under those assumptions, not to describe the probability that this completed trial detected an effect.

In general, smaller effects require more participants to detect with a specified power when other assumptions stay fixed. Such calculations also depend on the effect used, outcome variability or event rates, the analysis method, and the design assumptions. The trial’s own original sample-size assumptions are not reported in the registry record, so the planning illustrations should not be read as evidence that the trial was designed around these particular values.

11. Confidence Intervals and Precision

Precision is reflected in the width of a confidence interval: narrower intervals indicate less statistical uncertainty about the estimate under the analysis assumptions, while wider intervals leave more possible values compatible with the data. Precision is distinct from whether the estimate is clinically important or whether an analysis crosses a significance threshold.

The primary risk-difference interval extends from -0.187 to 0.124 around an estimate of -0.031. Because it includes zero and covers values on either side, the primary comparison does not precisely determine whether the event proportion was lower or higher in the TXA arm. The interval also allows differences larger in magnitude than the point estimate. The unadjusted p-value of 0.694 is consistent with substantial uncertainty, but the interval gives more direct information about the range of differences compatible with the analysis.

The mean difference for units transfused has a 95% confidence interval from -1.583 to 0.783. The calculated blood loss interval runs from -851.7 to 51.75 mL. Both include zero, so neither comparison rules out no difference under the analysis assumptions. The VTE risk-difference interval, from -0.029 to 0.091, also includes zero. Its event counts are small, and the interval permits a range of effects in either direction.

These intervals address sampling uncertainty in the posted comparisons. They do not correct for possible missing outcomes, measurement limitations, selective reporting, or multiple testing. The registry record does not report enough detail to assess those issues fully. A confidence interval should therefore be read as one part of the evidence, alongside the trial design, endpoint definitions, and reporting limitations.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm for the primary and other non-time-to-event outcomes; they are not total event counts. They use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The planning effect is set at the stated fraction of the observed effect, with illustrations for 100%, 75%, and 50% of that effect. The original design assumptions for the completed trial are not reported in the registry record.

The 80% power column describes a planning target: under the stated assumptions and if the assumed effect were the true effect, a study of the indicated size would have an 80% chance of rejecting the no-difference hypothesis using the specified test. The 90% power column uses a higher chance target and therefore generally calls for more participants under otherwise similar assumptions. Power is a design property calculated for a chosen effect and analysis; it is not a measure of the probability that the trial’s result is correct.

For example, the primary-endpoint illustration lists 3,249 participants per arm when planning for 100% of the observed effect and 13,213 per arm when planning for 50% of the observed effect, for the 80% power target. The corresponding 90% planning figures are 4,348 and 17,688 participants per arm. The increase in the required size as the assumed effect becomes smaller illustrates a general statistical principle: smaller differences are harder to distinguish from random variation.

These calculations are planning illustrations, not observed power. They are based on the observed effect rather than a documented original protocol justification. The registry record does not report whether the trial’s own sample-size calculation used different assumptions, or whether it included other considerations such as losses to follow-up.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.297; treatment proportion p₁ = 0.266; average p̄ = 0.281.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6358 = 1.2462.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6355 = 0.5348.
4. n = (1.2462 + 0.5348)² / (-0.0312)² = 3,248.3, rounded up to 3,249 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.296875                          # control proportion
p1 <- 0.265625                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(3182751)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 3,249 (80% power), 4,348 (90% power)
 75% of observed effect: n per arm = 5,824 (80% power), 7,797 (90% power)
 50% of observed effect: n per arm = 13,213 (80% power), 17,688 (90% power)
power.prop.test: 3248.3 
Simulated power at n = 3,249 per arm: 0.800 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes. The posted comparisons include unadjusted p-values. The registry record does not report whether the investigators planned to adjust for multiple testing, define a testing hierarchy, or designate particular secondary outcomes as confirmatory. Without that information, an isolated p-value among multiple outcomes should not be treated as if it came from a single prespecified test.

The registry record does not report a detailed statistical analysis plan, interim analyses, or the original sample-size justification. It also does not report whether outcomes were analyzed according to intention to treat, per protocol, or another analysis population. The assigned-arm summaries are available, but the analysis population and handling of any deviations from assigned treatment are not described in the information reported.

Missing-data handling is not reported in the registry record. The posted arm counts for the primary outcome are 64 in each arm, but these counts alone do not establish whether every randomized participant had complete outcome information or how missing observations, if any, were treated. No imputation approach, sensitivity analysis, or reasons for missing outcome data are reported.

These omissions matter because analysis choices can affect uncertainty and interpretation. For example, the interpretation of a treatment comparison may differ depending on whether all randomized participants are included, how outcome data are handled, and whether multiple comparisons were anticipated. The registry summaries remain useful as a record of the reported outcomes and estimates, but the unreported details limit independent assessment of the full analysis process.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: wound complication (6.2%), deep vein thrombosis (dvt) (4.7%), stroke (4.7%), myocardial infarction (3.1%), pulmonary embolism (pe) (1.6%).

The registry reports serious adverse events in 8 participants in the tranexamic acid arm and 7 in the control arm. It reports other adverse events in 0 participants in each arm. Deaths are reported for 7 participants in the TXA arm and 6 in control. These are separate registry figures; the record does not describe their overlap or provide enough detail to interpret them as mutually exclusive categories.

The serious adverse event terms listed most frequently are wound complication at 6.2%, deep vein thrombosis at 4.7%, stroke at 4.7%, myocardial infarction at 3.1%, and pulmonary embolism at 1.6%. The registry summary does not provide arm-specific counts for each listed term in this information, so these percentages should not be attributed to one arm or compared between arms.

Adverse-event summaries describe events recorded during the trial; they do not, by themselves, establish that an event was caused by the assigned treatment. The registry record does not provide event-level timing, severity definitions, relatedness assessments, or detailed follow-up for these safety outcomes. The counts should therefore be read descriptively, with the size and reporting detail of the trial in mind.

16. What the Result Does, and Does Not, Mean

The posted results show that 17 participants in the tranexamic acid arm and 19 in the control arm were transfused with at least one unit of packed red blood cells during hospitalization. The estimated risk difference is -0.031, but its confidence interval includes no difference and spans values in both directions. The comparison therefore leaves substantial uncertainty about the size and direction of the underlying difference.

The secondary summaries add information about transfusion quantity, calculated blood loss, and symptomatic VTE, but their estimates also have uncertainty and do not all point in the same direction. They address separate outcomes, and their unadjusted status and the absence of a reported multiplicity plan limit how strongly they can be interpreted collectively. Safety counts are descriptive and do not establish whether events were caused by treatment.

These results do not show that the two assigned treatments are equivalent. Demonstrating equivalence would require a prespecified equivalence margin and an analysis designed to assess that question; such a plan is not reported in the registry record. Likewise, the results do not establish that one treatment has a particular effect in all patients with hip fractures or in settings beyond the study population and outcome definitions recorded.

The registry record supports a narrower reading: it reports a randomized, masked comparison and gives event counts and effect estimates for the outcomes described. The primary estimate points toward fewer transfused participants in the TXA arm, but its uncertainty is broad. The posted information is useful for understanding the observed data and planning future studies, while leaving important details about analysis populations, missing data, multiplicity, and the original design assumptions unreported.

17. Why This Trial Matters Statistically

This trial illustrates why a point estimate should not be interpreted in isolation. The primary estimate points in one direction, but the confidence interval includes no difference and values on either side. Reporting the estimate together with its interval makes the uncertainty visible and discourages treating a single observed contrast as a settled answer.

It also highlights that related clinical outcomes are not interchangeable. Whether a participant received a transfusion, how many units were given, and calculated blood loss describe different aspects of the perioperative experience. The secondary outcome pattern is not uniform in direction, so each outcome needs to be interpreted according to its own definition and precision.

The registry’s planning illustrations provide another statistical lesson: the sample size needed for a future study depends on the effect the study is designed to detect. Planning for a smaller effect requires more participants under otherwise similar assumptions. Because these illustrations start from observed effects, they are not evidence of the completed trial’s original design rationale or of its observed power.

Finally, the record demonstrates the value of transparent reporting and the consequences when important analysis details are absent. Information about missing data, multiplicity, analysis populations, and the original sample-size calculation would help readers evaluate how robust the reported comparisons are. The trial is therefore informative not only for its outcome summaries, but also as an example of why estimates, uncertainty, design context, and reporting completeness belong together in statistical interpretation.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record leaves several trial-specific uncertainties. It does not report the randomization sequence-generation or allocation-concealment procedures, nor does it identify which roles were masked under the quadruple-masking designation. These details are relevant when assessing implementation and possible sources of bias.

The primary transfusion endpoint depends on clinical decisions made in the context of hemoglobin values, symptoms, and cardiac history. The registry describes criteria under which transfusion would be considered, but does not report individual values, application of criteria, or reasons for each transfusion. The record also does not explain how calculated blood loss was derived, which can limit assessment of its measurement properties.

Analysis populations, missing-data handling, protocol deviations, and the original sample-size justification are not reported in the registry record. A multiplicity strategy and interim-analysis procedures are also not reported. These omissions make it difficult to determine whether the posted summaries correspond to a prespecified analysis plan or how sensitive they might be to alternative analysis choices.

The primary confidence interval is broad, and the VTE comparison is based on few reported events. The registry’s safety summary does not provide detailed arm-specific counts for each serious adverse event term, event timing, or relatedness assessments. In addition, detailed comparative analyses are not reported in the registry record for every listed secondary outcome. These limitations counsel against broad conclusions from the posted summaries and support reading each estimate with its endpoint definition and uncertainty.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Does Early Administration of Tranexamic Acid Reduce Blood Loss and Perioperative Transfusion Requirement — NCT03182751.
• Registry record last updated 2023-03-30; status last verified 2023-03.
• Results first posted 2023-03-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

The registry describes a completed phase 2 randomized, quadruple-masked, parallel-group trial sponsored by Mayo Clinic. Enrollment was 128, with 64 participants in each reported arm. The study compared early tranexamic acid with placebo in low-energy hip fracture patients.

The primary endpoint was transfusion of at least one unit of packed red blood cells during hospitalization. Counts were 17 in the TXA arm and 19 in control. The risk difference was -0.031, with a 95% confidence interval from -0.187 to 0.124 and an unadjusted p-value of 0.694. The interval includes no difference and indicates substantial uncertainty.

Posted secondary summaries cover units transfused, calculated blood loss, and symptomatic VTE. Their estimates are uncertain and do not all point in the same direction. The registry also reports serious adverse event and death counts. Details about multiplicity, missing data, analysis populations, and the original design assumptions are not reported in the registry record.