Topical Tranexamic Acid (TXA) in Joint Arthroplasty: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Topical Tranexamic Acid (TXA) in Joint Arthroplasty (NCT01937559), a randomized phase 4 study. The primary outcome is Post-operative Blood Loss.

2. Clinical Question

The registry describes a study of tranexamic acid (TXA) in people undergoing joint arthroplasty, with osteoarthritis, hip arthropathy, and shoulder arthropathy listed as conditions. Its stated objective was to evaluate whether topical TXA could reduce blood loss after shoulder arthroplasty and primary total hip arthroplasty. The posted results also include an intravenous TXA group, alongside topical TXA and saline.

The primary question concerns postoperative blood loss, reported as a mean in mL. The registry defines the measure through changes in hemoglobin during the hospital stay: the difference between preoperative hemoglobin and the lowest postoperative hemoglobin during the stay, or the lowest postoperative hemoglobin before a transfusion. Surgical drain output was part of the investigators’ stated rationale, but the posted primary outcome is the hemoglobin-based measure.

The clinically relevant statistical comparisons are topical TXA versus saline and topical TXA versus intravenous TXA. In the posted results, mean blood loss was 1063.0 mL for topical TXA, 1205.0 mL for saline, and 933.9 mL for intravenous TXA. The reported comparison estimates and confidence intervals describe how these group means differ and how much uncertainty remains around each estimate. They do not, by themselves, establish whether a difference is important to patients or clinically meaningful.

The registry also lists possible effects on transfusions, infection, hospital stay, and patient-reported outcomes. Among these, length of hospital stay has posted numerical results. Results for the other listed secondary outcomes are not reported in the registry record.

3. Trial Design

The registry identifies this as a Phase 4, randomized, double-masked, parallel-group study. It is marked completed. The sponsor is The Hawkins Foundation. The registry lists enrollment as 188, with a study start of 2013-04 and primary completion of 2018-06. These are record-level design and timeline details; they do not describe the reasons for the chosen enrollment or how the study was conducted at each site.

Three groups appear in the posted primary outcome results: topical TXA, saline, and intravenous TXA. The primary outcome includes 50 participants in the topical group, 50 in the saline group, and 66 in the intravenous group. These are the group counts attached to that outcome, and the registry’s overall enrollment figure should not be treated as interchangeable with those outcome-specific counts. The registry record does not report why the counts differ or provide a detailed account of participant flow.

The stated study objective focuses on topical TXA after shoulder arthroplasty and primary total hip arthroplasty. The registry lists osteoarthritis, hip arthropathy, and shoulder arthropathy as conditions, but the posted information does not give a detailed breakdown of participants by joint, diagnosis, or procedure. It also does not report whether the treatment comparisons were stratified by joint or whether results were analyzed separately for shoulder and hip procedures.

Although the trial is described as double-masked, the registry record does not specify which individuals were masked or how masking was maintained. The record does not report the randomization method, allocation concealment procedures, the study’s original sample-size assumptions, or a detailed statistical analysis plan. These omissions limit how fully the design can be reconstructed from the registry alone.

The interventions are listed as TXA and normal saline, and the posted arms distinguish topical TXA, saline, and intravenous TXA. No further details about dose, timing, administration procedures, or treatment adherence are reported in the registry record. The design therefore supports describing the posted group comparisons, but not inferring protocol details beyond those explicitly recorded.

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:

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 Post-operative Blood Loss, measured over Duration of hospital stay, up to 4 days.

The primary endpoint is titled postoperative blood loss and is reported as a mean in mL with a standard deviation. The registry says it is calculated from the difference between preoperative hemoglobin and the lowest postoperative hemoglobin during the hospital stay, or the lowest postoperative hemoglobin before a blood transfusion. The stated timeframe is the duration of the hospital stay, up to 4 days.

This measure uses the change in hemoglobin as an indicator of blood loss during the perioperative period. Such a measure can be useful because it translates laboratory observations into a quantitative outcome that can be compared across treatment groups. The registry’s description also accounts for the possibility that a transfusion may occur before the lowest postoperative hemoglobin would otherwise be observed.

It is important to distinguish the registry’s measure from a direct volume measurement. Although the outcome is labeled blood loss and expressed in mL, the description defines it through hemoglobin values; it does not explain the conversion procedure or provide a separate validation of the measure. The investigators’ summary mentions surgical drain output as another outcome of interest, but the posted primary endpoint is the hemoglobin-based measure.

The primary endpoint is a continuous outcome, so the reported group means describe average values and the standard deviations describe variability among participants. A group mean difference estimates the contrast between two group averages. It does not show how individual participants’ outcomes were distributed, and a difference in means alone does not establish a clinically important change. The registry does not report a threshold for clinical importance.

7. Results Posted in the Registry

• Saline: mean 1,205 versus 1,063 on control; difference 141.72 (95% CI -4.34 to 287.78), standardized effect d = 0.38; z-test p = 0.057.
• Intravenous Tranexamic Acid (TXA): mean 933.92 versus 1,063 on control; difference -128.96 (95% CI -255.43 to -2.49), standardized effect d = -0.37; z-test p = 0.046.

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.

Length of Hospital Stay

• 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:
  • Saline: mean 1.64 versus 1.52 on control; difference 0.12 (95% CI -0.14 to 0.38), standardized effect d = 0.18; z-test p = 0.369.
  • Intravenous Tranexamic Acid (TXA): mean 1.39 versus 1.52 on control; difference -0.13 (95% CI -0.36 to 0.10), standardized effect d = -0.21; z-test p = 0.262.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Saline and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intravenous Tranexamic Acid (TXA) and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists a broad set of secondary outcomes, including perioperative transfusions, blood units transfused, surgical infections, length of hospital stay, and patient-reported outcomes. Numerical results are posted for length of hospital stay, but the registry record does not report results for the other listed outcomes. Consequently, the secondary evidence is incomplete relative to the range of outcomes described in the study record.

The available secondary outcome is related to the primary question in a broad sense: hospital stay may describe a different aspect of the postoperative course than the hemoglobin-based blood-loss measure. Its posted group means are relatively similar, and the reported comparison intervals include no difference. This does not confirm or refute the primary outcome pattern; the outcomes measure different things and have different variability and uncertainty.

Secondary findings generally carry less weight when many outcomes or comparisons are examined without a reported plan for controlling multiplicity. Each additional analysis creates another opportunity for an apparently notable result to arise by chance. Here, the registry lists multiple outcomes and two primary-group contrasts, while the p-values are explicitly unadjusted and the analysis plan is not reported. The available record therefore does not establish which secondary comparisons, if any, were prespecified as confirmatory.

Missing numerical results also prevent a balanced assessment across the full set of outcomes. The absence of posted results must not be interpreted as evidence that no events occurred or that groups were alike. The registry record does not report those outcomes’ group counts, estimates, or uncertainty. The safest overall reading is that the secondary evidence adds limited context to the primary blood-loss comparisons, with the hospital-stay result available and the other listed outcomes not reported in the registry record.

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

• Number of Participants With Perioperative Blood Transfusions
• Number of Blood Units Transfused
• Rate of Surgical Infections
• Length of Hospital Stay
• Patient-reported Outcomes Scores, Including Euroqol-5D (EQ-5D), Global Rating of Change Scale (GRoC), and Single Alpha Numeric Evaluation (SANE).
• Patient-reported Outcome Scores Including the Harris Hip Score and Western Ontario and McMaster Universities Arthritis Index (WOMAC)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous: each participant contributes a blood-loss value expressed in mL, and the registry reports group means and standard deviations. A mean summarizes the average value in a group. A standard deviation describes how spread out participant values are around that group’s mean; it is not the uncertainty in the mean itself. The standard error, by contrast, describes the estimated sampling uncertainty of a mean. The posted results include standard errors for each group in the comparisons.

What does a mean difference represent?

A mean difference subtracts one group mean from another. The direction depends on the order used for the subtraction, so the comparison definition matters. For saline versus topical TXA, the estimate is saline minus topical TXA. For intravenous TXA versus topical TXA, it is intravenous TXA minus topical TXA. A positive or negative sign describes direction under that definition; it does not mean that the result is automatically favorable or important.

For the primary outcome, the saline comparison has an estimate of 141.7 mL, while the intravenous comparison has an estimate of -129.0 mL. These are estimates of differences between group averages, not values observed in every participant. The group standard deviations indicate appreciable variability in measured blood loss. The registry does not provide participant-level distributions, so the mean and standard deviation cannot show the full shape of the outcome data or reveal whether a small number of observations strongly influenced the averages.

How should confidence intervals be read?

A confidence interval expresses uncertainty around an estimated effect. It gives a range of values reasonably compatible with the data under the statistical method used. A narrow interval indicates more precision than a wide interval, while an interval that includes zero for a difference does not clearly distinguish the estimate from no difference at the interval’s confidence level. The registry record does not specify the confidence level or the method used to construct these intervals, so interpretation should stay with the posted ranges rather than assume additional methodological details.

The saline comparison interval extends from -4.34 to 287.8 mL, crossing zero. The intravenous comparison interval extends from -255.4 to -2.486 mL, remaining on the negative side but with an endpoint close to zero. Both ranges show that the exact magnitude is uncertain. An interval is not a list of possible individual outcomes, and it does not mean that all values inside it are equally likely.

What do the p-values add?

The posted p-values are unadjusted: 0.057 for saline versus topical TXA and 0.046 for intravenous TXA versus topical TXA. A p-value summarizes how unusual results at least as incompatible with a no-difference statistical model would be, if that model and the analysis assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of a difference. Small changes around a conventional threshold should not erase the continuous information in the estimate and interval.

Because the p-values are unadjusted, they do not account for the possibility of false-positive findings arising from multiple comparisons or multiple outcomes. The registry lists several secondary outcomes and provides more than one treatment comparison. The record does not report a multiplicity plan, so these p-values should not be interpreted as if a family-wise adjustment had been applied. The registry also reports no analysis descriptions, so details such as covariate adjustment and the precise inferential procedure are not available.

Why do variability and over-dispersion matter?

General statistical explanation: variability matters because a mean difference is estimated less precisely when individual measurements vary substantially relative to the amount of information in the groups. When outcome data are more variable than a statistical model expects, standard errors and confidence intervals can be too small if the model does not account for that extra variation; this is one reason over-dispersion matters for analyses that assume a particular variance structure. The posted endpoint is summarized with means and standard deviations, but the registry does not report diagnostics or a model assessment. No claim about over-dispersion in this trial can therefore be made from the record.

The posted comparisons use the group means, standard deviations, and sample counts to describe unadjusted contrasts. Their numerical estimates are recalculated summary-statistic comparisons; the registry record does not describe a separate inferential model for them. There is no reported discrepancy between these recalculations and a sponsor analysis, and the record does not provide an analysis description to compare against.

The distinction between statistical and clinical interpretation remains important. Statistical methods quantify uncertainty given data and assumptions. They cannot determine from the numerical contrast alone what size of blood-loss change matters to patients, whether the measurement captures all relevant consequences, or whether the result is consistent across procedures. The registry record does not report a minimally important difference or a detailed analysis plan that would resolve those questions.

11. Confidence Intervals and Precision

The confidence intervals show that the estimated mean differences are not known with high precision. For saline versus topical TXA, the estimate is 141.7 mL, with an interval from -4.34 to 287.8 mL. Because that range includes zero, the data do not clearly rule out no difference under the interval procedure. The interval also extends to values indicating a sizeable positive difference under the stated subtraction order, so the magnitude remains uncertain.

For intravenous TXA versus topical TXA, the estimate is -129.0 mL, with an interval from -255.4 to -2.486 mL. The interval lies on the negative side but approaches zero at its upper limit. It is consistent with estimates ranging from a larger negative difference to a small one. This is a more informative description than the p-value alone because it communicates both direction and a range of magnitudes compatible with the data.

The confidence intervals do not capture every source of uncertainty. They quantify sampling uncertainty under the method used, while uncertainty about measurement, study conduct, missing outcomes, and differences between hip and shoulder procedures may not be reflected. The registry record does not provide details sufficient to assess those issues or the interval-construction method. It also does not report a threshold that would help judge whether any part of either interval represents a clinically important difference.

Thus, the posted estimates support a cautious reading: the exact effects are uncertain, the saline contrast is compatible with no difference, and the intravenous contrast is estimated in the negative direction but remains imprecise in magnitude. Statistical precision and clinical importance are separate questions, and the latter is not resolved by the registry results.

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 a report of the study’s original design calculations. For these continuous outcomes, the figures are participants per arm, not total events. The calculation assumptions listed in the registry are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The original trial’s own sample-size assumptions are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm for a design with an 80% chance of detecting the specified effect, if the planning assumptions and effect are correct. The 90% power column gives the corresponding planning number for a higher chance of detection. These are design concepts, not guarantees that a future study will detect an effect, and they do not describe the probability that the posted trial result is true.

Rows planning for 100%, 75%, and 50% of the observed effect represent progressively smaller effects to detect. Smaller effects are harder to distinguish from random variation, so the illustrations require more participants per arm. The resulting numbers are sensitive to the observed effect used as the starting point; an effect estimated imprecisely in a relatively small study may not be a stable basis for planning.

The curve represents this general relationship between the effect size to be detected and the number of participants needed under the stated assumptions. It should be read as a planning aid, not as a reconstruction of the trial’s protocol. This is not observed power: it does not measure the probability that the completed trial detected its true effect.

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 = 141.720; pooled standard deviation σ = 372.608.
2. n = 2 × (1.96 + 0.842)² × 372.608² / 141.720² = 108.5, rounded up to 109 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 <- 141.72                      # observed difference in means
sigma <- 372.607649210265                     # 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(1937559)
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 = 109 (80% power), 146 (90% power)
 75% of observed effect: n per arm = 193 (80% power), 259 (90% power)
 50% of observed effect: n per arm = 435 (80% power), 582 (90% power)
power.t.test: 109.5 
Simulated power at n = 109 per arm: 0.797 (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. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study evaluates several outcomes, treatment comparisons, or analyses. Even if each individual analysis uses a conventional threshold, examining many results increases the chance that at least one appears statistically notable by chance. The registry lists multiple secondary outcomes and reports comparisons of topical TXA with both saline and intravenous TXA. The posted p-values are unadjusted, and a multiplicity adjustment or a prespecified hierarchy of outcomes is not reported in the registry record.

This matters for interpretation, particularly for results close to a conventional significance threshold. The p-value of 0.046 for the intravenous comparison should not be treated as definitive evidence in isolation, nor should the 0.057 saline comparison be taken as proof of no difference. The confidence intervals and effect estimates convey more about magnitude and uncertainty, but they do not solve the multiplicity question. The original statistical analysis plan and any decision about which comparisons were primary are not reported in the registry record.

The record also does not describe the analysis population. It does not say whether results were based on all randomized participants, participants who received treatment, or participants with complete endpoint measurements. No missing-data strategy, participant flow, or reasons for missing measurements are reported. The outcome-specific group counts are posted, but they do not explain how participants came to be included in each analysis or whether exclusions occurred.

These gaps are important because the treatment effect may be affected if missing outcomes or exclusions are related to treatment assignment or participant outcomes. Without the analysis population and missing-data handling details, the posted summary statistics cannot establish how robust the results are to those possibilities. Likewise, randomization supports a comparison by treatment assignment only when the analysis and participant handling preserve the intended comparison; the record does not provide enough detail to assess this.

The registry record does not report interim analyses, stopping rules, or a detailed statistical plan. Their absence from the record is not proof that such procedures were or were not used. It means that they cannot be evaluated from the posted information. These limitations counsel against treating the unadjusted comparisons as a complete account of the trial’s confirmatory statistical evidence.

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 non-serious adverse event terms

The serious adverse event figures report zero affected participants in each posted group: 0 of 50 for topical TXA, 0 of 50 for saline, and 0 of 66 for intravenous TXA. The record also reports zero deaths in each group. No serious adverse event terms are listed. These are counts for the groups and outcomes recorded in the registry; they do not establish that no adverse events of any kind occurred.

For other adverse events, the registry reports 4 of 50 participants in the topical TXA group, 0 of 50 in the saline group, and 4 of 66 in the intravenous TXA group. The record does not provide event descriptions, severity details, timing, or an assessment of whether these events were related to study treatment. These figures should therefore be read as counts reported under the registry’s other-adverse-event category, not as a characterization of event type or cause.

Zero recorded serious events in these groups is not evidence that the risk is zero. The trial’s group counts are limited, and the registry does not give additional follow-up details or definitions that would support broader conclusions. The safety data describe what was posted, not the full range of possible risks.

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

The results describe group averages for the registry’s hemoglobin-based postoperative blood-loss measure and the uncertainty around two comparisons with topical TXA. The saline group mean is higher than the topical TXA group mean, while the intravenous TXA group mean is lower. The confidence intervals indicate that the first contrast is compatible with no difference and that the second is estimated in a negative direction but has a range of plausible magnitudes close to zero at one end.

These observations do not establish whether any difference is large enough to matter clinically. The registry does not report a threshold for a meaningful change, and the outcome’s description does not provide enough detail to assess the conversion from hemoglobin change to mL. Statistical evidence about group averages is not equivalent to evidence about every participant’s outcome, and the record does not provide participant-level data.

The study’s stated objective includes shoulder arthroplasty and primary total hip arthroplasty, but the posted results are not separated by procedure. The record therefore does not show whether the overall pattern is similar in each type of surgery. It also does not report adjustment for other factors or describe the analysis population, missing data, or multiplicity strategy. Those limits matter when considering how confidently the observed contrasts can be attributed to treatment assignment.

The posted length-of-stay results provide a secondary measure, but they do not resolve the interpretation of blood loss. Numerical findings for the other listed secondary outcomes are not reported in the registry record. Likewise, the adverse-event counts are limited to the categories and details recorded; they do not establish the absence of risk.

The result is best understood as a set of uncertain comparisons from a completed randomized study, rather than as a universal conclusion about TXA in all joint arthroplasty settings. The registry information supports describing the observed means, estimates, and intervals. It does not support a recommendation about treatment or a conclusion that a particular approach works or does not work.

17. Why This Trial Matters Statistically

This trial is statistically instructive because it reports a continuous primary outcome as means and standard deviations, then presents comparisons among three treatment groups. The contrast order matters: the saline estimate is calculated as saline minus topical TXA, while the intravenous estimate is intravenous TXA minus topical TXA. Reading the sign correctly is necessary before describing the direction of either estimate.

The two comparisons also illustrate why point estimates, confidence intervals, and p-values should be read together. A p-value near a conventional cutoff does not summarize the size or precision of an effect. The interval for saline versus topical TXA includes zero, whereas the interval for intravenous TXA versus topical TXA is on the negative side but approaches zero. That difference in statistical evidence does not by itself settle clinical importance.

The registry’s broad list of secondary outcomes raises a practical issue in clinical research: multiple endpoints can create a complicated evidentiary picture, especially when the analysis plan and multiplicity handling are not available. The absence of posted numerical results for most listed secondary outcomes further limits cross-outcome interpretation. A reader should distinguish unreported outcomes from outcomes with a reported null finding.

Finally, the registry highlights the gap between trial enrollment and outcome-specific analysis counts. The primary endpoint group counts are available, but participant flow and analysis-population details are not. A complete interpretation needs both effect estimates and a transparent account of who contributed data and how analyses were planned. The posted statistics offer a useful basis for describing uncertainty, while leaving important methodological questions unresolved.

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.

Several limitations are specific to the information available for this trial. The primary outcome is defined using changes in hemoglobin but is expressed as blood loss in mL; the registry does not describe the conversion method or report a separate direct measurement to clarify that relationship. This makes it important to interpret the endpoint according to its stated definition rather than assume it is a direct volume measurement.

The study objective includes shoulder and primary total hip arthroplasty, but the posted primary results are not divided by procedure or joint. The registry also lists more than one condition and does not report a detailed participant profile. It is therefore not possible to determine whether the reported averages represent comparable mixes of procedures or diagnoses across groups.

The registry gives overall enrollment of 188 and primary-outcome counts of 50, 50, and 66, but does not explain participant flow or the analysis population. Reasons for missing data, exclusions, and the handling of incomplete outcomes are not reported in the registry record. This prevents assessment of whether the outcome summaries include all randomized participants.

The design information is also limited. The record labels the study randomized and double-masked but does not describe the randomization process, who was masked, allocation concealment, treatment dose or timing, or adherence. It does not report the original sample-size justification, detailed statistical plan, or multiplicity strategy. These details cannot be inferred from the posted results.

Finally, only length of hospital stay has posted numerical secondary results among the listed secondary outcomes. Results for transfusions, blood units, infections, and patient-reported outcomes are not reported in the registry record. The available adverse-event information is also limited in detail. These gaps constrain the broader assessment of outcomes and safety.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Topical Tranexamic Acid (TXA) in Joint Arthroplasty — NCT01937559.
• Registry record last updated 2020-05-05; status last verified 2020-04.
• Results first posted 2020-05-05.
• 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 record describes a completed Phase 4 randomized, double-masked, parallel-group study of topical TXA in joint arthroplasty, with saline and intravenous TXA groups represented in the posted results. Overall enrollment is listed as 188; the primary outcome counts are 50 for topical TXA, 50 for saline, and 66 for intravenous TXA.

The primary endpoint is postoperative blood loss, reported as a mean in mL and defined using the difference between preoperative hemoglobin and the lowest postoperative hemoglobin during the hospital stay or before transfusion. The posted group means are 1063.0 mL, 1205.0 mL, and 933.9 mL, respectively. The comparisons have unadjusted p-values of 0.057 and 0.046, with confidence intervals that indicate uncertainty in the estimated differences.

Length of hospital stay is the secondary outcome with numerical results posted. Other listed secondary outcomes are not reported in the registry record. Serious adverse events and deaths are reported as zero in all groups; other adverse-event counts are also posted, without event details. The registry does not report the original sample-size assumptions, analysis population, missing-data approach, multiplicity plan, or detailed statistical analysis plan.