Study Of Tranexamic Acid For The Reduction Of Blood Loss In Patients Undergoing Surgery For Long Bone Fracture: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study Of Tranexamic Acid For The Reduction Of Blood Loss In Patients Undergoing Surgery For Long Bone Fracture (NCT00824564), a randomized phase 4 study. The primary outcome is Total Blood Loss.

2. Clinical Question

3. Trial Design

The registry describes a prospective, randomized, Phase IV, open-label, parallel-group study. Participants were assigned to tranexamic acid plus standard of care or standard of care alone. Masking was listed as none, so the study was open label. The registry record does not report how the randomization sequence was generated, whether allocation was concealed, or how treatment assignment was implemented.

The study enrolled 82 participants and is listed as completed. Its recorded start was 2009-04, and primary completion was 2010-06. The primary analysis population was the full analysis set, defined as all participants randomized to study treatment who received at least one dose of study medication. Posted primary outcome summaries include 41 participants in the tranexamic acid group and 40 in the standard-care group. The registry record does not explain the difference between total enrollment and the numbers in those outcome summaries.

The study aimed to assess blood loss and transfusion requirements in long bone fracture surgery, primarily fracture shaft of femur. Standard care included routine surgical and anesthetic techniques used to control blood loss. The registry record does not report the planned sample-size justification, the intended treatment duration, the detailed dosing regimen, or the original statistical analysis plan.

The primary endpoint was total blood loss through Day 7 post-surgery. Other listed outcomes included intra-operative and post-operative blood loss, total blood loss assessed by Gross' formula, transfusions, hemoglobin changes at specified times, and deep vein thrombosis after surgery. The record lists seven secondary outcome measures, while the results summarized in the registry include several different outcome types. The number of study locations and other recruitment details are not reported in the registry record.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full analysis set (FAS) included all participants who were randomized to study treatment and received at least one dose of study medication.

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 Total Blood Loss, measured over Baseline through Day 7 post-surgery.

The primary endpoint was total blood loss, in milliliters, from baseline through Day 7 post-surgery. It was defined as the sum of intra-operative and post-operative blood loss. The registry describes measuring blood loss by weighing drapes, dressings, or swabs before and after soaking and checking drain collectors until drains were removed.

This endpoint brings blood loss from different stages of the surgical episode into one continuous measure. Comparing group means can describe whether the average recorded total differed between the randomized groups. The mean is useful for summarizing a continuous measure, while the standard deviation describes how dispersed participants' measurements were around that group mean. The posted standard deviations indicate substantial variability in each group's measurements.

Blood loss is a direct study outcome for a trial intended to assess blood loss during fracture surgery. However, a group mean does not describe every participant's experience, and the summary alone does not show the distribution of individual outcomes. Measurement procedures, timing, and missing observations can affect interpretation; details about missing endpoint data and their handling are not reported in the registry record.

The full analysis set included randomized participants who received at least one dose of study medication. The registry reports a mean of 370.7 mL with a standard deviation of 180.7 in the tranexamic acid group and a mean of 426.2 mL with a standard deviation of 323.8 in the standard-care group. Those descriptive summaries are interpreted alongside the reported treatment comparison and its confidence interval, rather than as proof of a treatment effect by themselves.

7. Results Posted in the Registry

• Standard of Care: mean 426.20 versus 370.70 on control; difference 55.50 (95% CI -59.08 to 170.08), standardized effect d = 0.21; z-test p = 0.342.

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.

Intra-operative 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:
  • Standard of Care: mean 292.20 versus 316.20 on control; difference -24.00 (95% CI -87.93 to 39.93), standardized effect d = -0.16; z-test p = 0.462.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Standard of Care and the control. The interval gives the range of effects that remain compatible with the data.

Total Blood Loss Assessed by Gross' Formula

• 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:
  • Standard of Care: mean 798.00 versus 823.20 on control; difference -25.20 (95% CI -282.04 to 231.64), standardized effect d = -0.04; z-test p = 0.848.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Standard of Care and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants Receiving Transfusions

• 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:
  • Standard of Care: 15.0% (6/40) versus 12.2% (5/41) on control; risk difference 2.8 percentage points (95% CI -12.1 to 17.7), risk ratio 1.23 (0.41–3.71); unadjusted two-proportion z-test p = 0.713.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Standard of Care and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover related but distinct aspects of blood loss and transfusion. The registry lists intra-operative blood loss, post-operative blood loss, total blood loss assessed by Gross' formula, transfusion, hemoglobin changes at specified time points, and deep vein thrombosis after surgery. Six secondary results are described as posted in the registry, although numerical summaries for only some of those outcomes are included in the results presented for interpretation. Outcomes without numerical results in the registry record cannot be evaluated from the listed information.

Across the detailed secondary comparisons, there is no clear pattern that substantially changes the interpretation of the primary endpoint. The continuous blood-loss comparisons have confidence intervals that include zero, and the transfusion analysis reports a p-value above 0.05. Their uncertainty is consistent with the primary result being inconclusive rather than establishing a consistent difference across outcomes. These measures are related, but they are not interchangeable: intra-operative loss, total loss assessed with a different method, and transfusion capture different features of the surgical course.

Secondary outcomes can be useful for understanding the range of effects examined, but repeated testing creates a multiplicity concern. General statistical explanation: when many hypotheses are tested, the chance of at least one apparently unusual result can rise, even if none reflects a real effect. The registry record does not report a multiplicity adjustment or a prespecified hierarchy for secondary tests. Consequently, isolated secondary p-values deserve less weight than a prespecified primary result, especially when the endpoint pattern is not consistent.

The record also does not provide a complete account of missing secondary results or whether all listed outcomes were analyzed as planned. The number of secondary outcomes and analyses indicates that multiple comparisons were conducted, but does not reveal which analyses were prespecified or how results were selected for reporting. The secondary findings therefore provide context, not independent confirmation of a treatment effect.

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

• Intra-operative Blood Loss
• Post-operative Blood Loss
• Total Blood Loss Assessed by Gross' Formula
• Number of Participants Receiving Transfusions
• Change From Baseline in Hemoglobin Levels at End of Surgery, 1 hr Post-surgery, and Mornings of Day 1, Day 2, Day 4, Day 7 or Early Termination (ET) Post-surgery
• Number of Participants With Deep Vein Thrombosis (DVT) Post Surgery

9. Statistical Interpretation

10. Statistical Methods Explained

What does a group mean describe?

The primary endpoint is continuous, so the registry reports a mean and standard deviation for each group. The mean is the arithmetic average of participants' recorded blood loss. The standard deviation describes the spread of those observations around the mean; it is not the uncertainty in the mean itself. The reported means are 370.7 mL and 426.2 mL, and the reported standard deviations are 180.7 and 323.8, respectively. These summaries describe the observed groups and do not by themselves establish a treatment effect.

What does the mean difference represent?

A mean difference compares the average outcome in one group with the average in the other. Its sign depends on the order used for the subtraction. The sponsor reports the mean difference as -55.5 mL for the groups listed in its analysis. The unadjusted recalculation instead reports 55.5 mL for standard care relative to tranexamic acid plus standard care. These values express the same contrast in opposite directions. Reading the group order alongside the estimate is essential; a negative sign does not automatically mean benefit or harm.

What is a confidence interval?

General statistical explanation: a confidence interval gives a range of values compatible with the data and the analysis method at a stated confidence level. It reflects sampling uncertainty, not the range containing most individual participants' outcomes. A 95% confidence interval that includes zero for a mean difference indicates that the data do not rule out a zero difference at the corresponding two-sided threshold. It does not prove that the groups are identical. The sponsor's primary interval runs from -172.7 to 61.7, while the recalculated interval runs from -59.08 to 170.1 in the reverse direction. Both include zero and allow effects in either direction.

How should the p-value be read?

General statistical explanation: a p-value describes how unusual data at least as inconsistent with a specified null hypothesis would be if that null model and the analysis assumptions held. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. The sponsor reports p = 0.348 for the primary endpoint; the unadjusted recalculation reports p = 0.342. Neither is below 0.05. The registry record does not report a different threshold or a confirmatory testing strategy.

What method did the registry report?

The sponsor's primary comparison is listed as a two-sided t-test of the mean difference in final values. A t-test compares group means while accounting for variability and sample size under its assumptions. The registry does not report details such as an adjustment for baseline values, a model including other covariates, or diagnostics of assumptions. The recalculation uses the posted group summary statistics to form a simple unadjusted comparison. It is useful as a check on the broad interpretation, but it is not the sponsor's original analysis.

The trial's continuous secondary outcomes also use group means and standard deviations. The reported analysis for intra-operative blood loss is a two-sided t-test. The analysis for total blood loss assessed by Gross' formula is also a two-sided t-test. For transfusions, the registry lists a chi-squared analysis. A chi-squared test is a general method for assessing whether observed counts across categories differ between groups; it does not, by itself, quantify the magnitude or precision of that difference.

Why can over-dispersion matter?

General statistical explanation: over-dispersion means that observed variability is greater than a model assumes. When a continuous outcome has wide spread, the estimated mean difference may be uncertain, and confidence intervals may be wide. For counts or binary outcomes, extra variability relative to a simple model can also make standard errors and p-values unreliable if not handled appropriately. The primary blood-loss standard deviations are large relative to the group means, and the reported confidence interval is broad. The registry does not report a specific over-dispersion assessment or a model intended to address it, so no additional adjustment should be inferred.

Several statistical details remain unavailable. The registry record does not report a prespecified analysis plan, treatment of protocol deviations, imputation methods, sensitivity analyses, interim analyses, or a method for adjusting secondary comparisons for multiplicity. Those omissions limit how fully the statistical analysis can be reconstructed from the record. The posted tests and estimates can be described, but unreported methods should not be assumed.

11. Confidence Intervals and Precision

The sponsor-reported primary mean difference is -55.5 mL, with a 95% confidence interval from -172.7 to 61.7. The interval includes zero and spans values in both directions. It is therefore compatible with a range of possible group differences rather than a narrowly determined contrast. The unadjusted recalculation gives 55.5 mL, with a 95% confidence interval from -59.08 to 170.1, because it expresses the contrast in the opposite direction. That interval also includes zero.

General statistical explanation: confidence intervals communicate precision as well as direction. A narrower interval indicates less sampling uncertainty under the method used, while a wider interval indicates more. An interval including zero does not show that the true effect is exactly zero; it means that the data and method do not exclude zero at that confidence level. The interval also does not assign probabilities to individual values within its bounds.

The standard deviation of the primary outcome was 180.7 mL in the tranexamic acid group and 323.8 mL in the standard-care group. The differences in spread and the modest numbers in the posted analysis summaries contribute to the context for interpreting the estimate, though the registry record does not report a formal precision target. The observed standard deviations describe variability among participants, whereas the confidence interval describes uncertainty about the group contrast.

The secondary continuous outcomes also have intervals that include zero: the intra-operative blood-loss interval runs from -41.3 to 89.3 for the sponsor's reported direction, and the Gross' formula interval runs from -238.2 to 288.6. These intervals are broad relative to their estimates. The transfusion comparison has no posted confidence interval in the sponsor analysis record. Taken together, the registry results are not precise enough to support a narrow conclusion about the size or direction of differences.

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 sample-size figures are planning illustrations based on the observed effect, not the trial's original design calculation. For these non-time-to-event outcomes, the figures are participants per arm, not total participants. The assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect. The trial's own sample-size assumptions and justification are not reported in the registry record.

Each planning row describes a different target effect: 100% of the observed effect, 75% of the observed effect, or 50% of the observed effect. The columns for 80% and 90% power describe the number of participants per arm that the planning calculation estimates would be needed to have the stated probability of detecting that target effect under the assumptions, if the effect and model assumptions held. Higher power targets require more participants than lower power targets for the same effect.

For the primary endpoint, the illustration based on 100% of the observed effect gives 349 participants per arm for 80% power and 466 participants per arm for 90% power. The rows targeting 75% and 50% of the observed effect require progressively more participants per arm. This reflects a general planning principle: smaller effects are harder to distinguish from random variation and therefore need more participants for the same power target. The figures are hypothetical planning values, not evidence about the trial's actual design or results. This is not observed power.

A sample-size curve can be read in the same way: it relates the planned effect size to the number of participants required under the stated assumptions. The curve does not show what the trial achieved, establish that a target effect is clinically important, or account for design features that are not stated. These illustrations are especially sensitive to the observed effect used as their starting point, so they should not be read as a definitive recommendation for a future study.

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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 55.500; pooled standard deviation σ = 261.328.
2. n = 2 × (1.96 + 0.842)² × 261.328² / 55.500² = 348.0, rounded up to 349 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
delta <- 55.5                      # observed difference in means
sigma <- 261.328416491247                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(824564)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 349 (80% power), 466 (90% power)
 75% of observed effect: n per arm = 619 (80% power), 829 (90% power)
 50% of observed effect: n per arm = 1,393 (80% power), 1,864 (90% power)
power.t.test: 349 
Simulated power at n = 349 per arm: 0.791 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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. Analyses Reported by the Sponsor

The registry reports the sponsor's primary analysis as a two-sided t-test, with a mean difference of -55.5 mL, a 95% confidence interval from -172.7 to 61.7, and p = 0.348. The unadjusted recalculation from the posted summary statistics gives a mean difference of 55.5 mL, a 95% confidence interval from -59.08 to 170.1, and p = 0.342. The estimates use opposite comparison directions, so their signs are reversed. Both intervals include zero, and both p-values are above 0.05.

The recalculation is a simple unadjusted calculation from group-level summaries. It is not a reconstruction of every possible feature of the sponsor's analysis and does not replace the registry's reported test. Small differences between the reported and recalculated intervals and p-values are present; the registry record does not explain them. The discrepancy flag is false, and the broad interpretation is alike: the primary comparison is statistically uncertain, with an interval that allows effects in either direction.

The sponsor's analysis should remain the principal reported result because it is the analysis recorded for the trial. The recalculation is a complementary check on the posted summary statistics, not a basis for selecting whichever estimate is preferred. Neither analysis establishes equivalence, and neither shows that the true effect is exactly zero.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when more than one outcome, time point, or comparison is tested. General statistical explanation: if each test uses the same nominal significance threshold, testing many hypotheses can increase the chance of at least one false-positive finding. Common approaches include a prespecified hierarchy, adjustment of the threshold, or clear designation of exploratory outcomes. The registry record does not report a multiplicity adjustment, a testing hierarchy, or a detailed plan for interpreting the secondary analyses. The secondary results should therefore not be treated as if each were a separate confirmatory test.

The record lists seven secondary outcome measures and 14 analyses. Several measures involve multiple time points, including hemoglobin changes at specified times after surgery. The presence of multiple analyses does not establish that all were planned in advance, nor does it show how the sponsor accounted for their number. Those details are not reported in the registry record.

The primary analysis population is defined as the full analysis set: randomized participants who received at least one dose of study medication. The primary outcome summaries include 41 participants receiving tranexamic acid plus standard care and 40 receiving standard care. Although total enrollment is listed as 82, the registry record does not explain the difference between enrollment and the numbers in the primary summaries. It also does not report the number of participants with missing primary measurements, reasons for missingness, or how missing values were handled.

The registry record does not report an intention-to-treat analysis definition beyond the stated full analysis set, a per-protocol analysis, imputation, sensitivity analyses for missing data, or rules for treatment discontinuation and protocol deviations. These omissions matter because analysis populations and missing-data assumptions can influence estimates. They do not establish that the sponsor used an inappropriate method; they mean the posted record does not permit a full assessment of those choices.

Interim analyses and any associated decision rules are not reported in the registry record. The original statistical plan, including prespecified covariates and the planned sample-size justification, is also not reported. As a result, the available record supports interpretation of the posted estimates and tests, but not a complete audit of the analysis strategy or reporting process.

16. Safety Results

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

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

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: deep vein thrombosis (7.3%), cardiac failure (2.5%), fat embolism (2.4%).

The registry reports serious adverse events affecting 4 of 41 participants in the tranexamic acid plus standard-of-care group and 1 of 40 participants in the standard-care group. It separately reports other adverse events affecting 28 of 41 and 26 of 40 participants, respectively. These are descriptive counts in the registry record; they do not by themselves establish that treatment caused an event or that event rates differ reliably between groups.

The serious adverse event terms listed include deep vein thrombosis at 7.3%, cardiac failure at 2.5%, and fat embolism at 2.4%. The record does not provide enough detail in the listed information to attribute these terms to a particular group or to interpret the percentages as comparative treatment effects. The registry lists deep vein thrombosis as a secondary outcome as well, but the numerical secondary result is not included in the outcome summaries.

Deaths are listed as null for both groups; death counts are therefore not reported in the registry record. The record does not provide event-level timing, severity details beyond the serious classification, or a causal assessment. These safety summaries should be read as adverse-event reporting, not as evidence of a treatment effect on safety.

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

The posted primary result describes average total blood loss through Day 7 post-surgery in a randomized comparison of tranexamic acid plus standard care with standard care alone. The group means were 370.7 mL and 426.2 mL. The sponsor-reported mean difference was -55.5 mL, with a 95% confidence interval from -172.7 to 61.7 and p = 0.348. The interval includes zero and permits differences in either direction, so the trial result does not establish a statistically clear difference in the primary endpoint.

That conclusion is not the same as proving there is no effect. A non-significant result may reflect an effect close to zero, substantial variability, limited precision, or some combination of factors. The posted interval is broad, so the estimate does not narrowly identify the size of any difference. The trial also does not establish equivalence: no equivalence margin or non-inferiority design is reported in the registry record.

The findings describe the participants and analyses recorded for this study. They do not establish what would happen in every setting or for every type of fracture surgery. The study description focuses on long bone fracture surgery, primarily fracture shaft of femur, and the registry lists femoral fractures as a condition. Further details about the enrolled population and study sites are not reported in the registry record.

The secondary outcomes do not provide a decisive resolution of the primary uncertainty. Their tests are also subject to multiplicity, and the registry record does not describe an adjustment strategy. The safety figures are descriptive and should not be interpreted as causal comparisons without a suitable analysis and fuller event information.

Overall, the record supports a cautious statistical reading: it reports group-level differences, but the primary confidence interval and p-value do not establish a clear difference. The result neither proves that the groups are identical nor establishes a benefit or harm. It is a description of the posted evidence from this trial, with meaningful uncertainty remaining.

18. Why This Trial Matters Statistically

This trial illustrates why an observed difference in group means is not enough to establish a treatment effect. The primary group means differ, but their comparison must be read with its uncertainty. The sponsor's confidence interval extends across zero and includes values in both directions, while the p-value does not meet the conventional 0.05 threshold. The central statistical lesson is to interpret the estimate and interval together, rather than treating the group means or a single p-value as a complete answer.

The study also illustrates the distinction between variation among participants and precision about a group contrast. The primary standard deviations are substantial, and the posted analysis includes around forty participants in each group. The wide interval is a reminder that a mean can be estimated with limited precision when the outcome is variable and the available sample is modest. The registry record does not state whether this level of precision matched the trial's original design goals.

Randomization supports a comparison between assigned groups, while open-label conduct raises questions about the potential influence of knowledge of assignment on care and measurement. The record does not report whether outcome assessors were blinded or whether allocation was concealed. Those details matter when interpreting outcomes that may depend on measurement procedures.

Finally, the registry's several secondary outcomes show why multiplicity and prespecification matter. A collection of tests is not equivalent to one confirmatory test, particularly when the analysis plan and adjustment strategy are not reported. Together, these features make the trial useful for teaching careful reading of estimates, confidence intervals, analysis populations, and the limits of registry reporting.

19. 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 primary analysis summaries cover 41 participants in the tranexamic acid group and 40 in the standard-care group, while total enrollment is listed as 82. The registry record does not explain the difference. It also does not report how many participants had missing primary endpoint data, whether all randomized participants were analyzed, or how missing measurements were handled. The full analysis set excludes randomized participants who did not receive at least one dose, according to its stated definition.

The study was open label. The registry does not report whether blood-loss measurements were assessed by personnel unaware of treatment assignment, whether allocation was concealed, or whether the measurement process was standardized across groups beyond the listed weighing and drain procedures. Those unreported details limit assessment of potential measurement or conduct biases.

The primary result has a broad confidence interval, and the group standard deviations indicate substantial variability. The registry record does not state an original sample-size target or its justification, so the planning illustrations based on the observed effect cannot establish whether the trial was designed for adequate precision. The dose and timing of tranexamic acid are also not reported in the registry record.

There are multiple secondary outcomes and analyses, but no reported multiplicity strategy or complete statistical analysis plan. The registry record does not report interim analyses, prespecified covariate adjustment, sensitivity analyses, or a detailed account of protocol deviations. Some listed secondary results are not numerically described in the record details available for interpretation. The safety data are likewise limited: deaths are not reported, and the serious-event terms are not presented with full group-specific event details. These limitations constrain both the statistical and clinical interpretation without establishing that any particular analysis choice was incorrect.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Study Of Tranexamic Acid For The Reduction Of Blood Loss In Patients Undergoing Surgery For Long Bone Fracture — NCT00824564.
• Registry record last updated 2011-06-28; status last verified 2011-06.
• Results first posted 2011-06-28.
• 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.

23. Record Summary

NCT00824564 is a completed, randomized, Phase IV, open-label, parallel-group study of tranexamic acid plus standard care versus standard care alone for surgery for long bone fracture. The registry lists 82 enrolled participants and records the study start as 2009-04 and primary completion as 2010-06. Its stated focus was blood loss and transfusions, primarily in fracture shaft of femur surgery.

The primary endpoint was total blood loss through Day 7 post-surgery. The sponsor-reported comparison was a mean difference of -55.5 mL, with a 95% confidence interval from -172.7 to 61.7 and p = 0.348. The interval includes zero and is broad, leaving considerable uncertainty about the size and direction of the group difference. The record also describes secondary outcomes and adverse events, but does not report several design and analysis details needed for a complete assessment.