This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Hip Fracture Study of GSK576428 (Fondaparinux Sodium) (NCT00320424), a non-randomized phase 3 study. The primary outcome is Rate of Major Bleeding During Treatment Period.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00320424 |
| Phase | Phase 3 |
| Condition | Thromboembolism |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 48 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing hip fracture surgery who entered the study and received fondaparinux. The primary endpoint population was the full analysis set: participants assigned to study drug, except those who received no study drug or had no valid efficacy data.
Intervention
Fondaparinux sodium 2.5 mg given subcutaneously, with intended treatment beginning 24±2 hours after surgical closure.
Comparator
There was no concurrent comparator group in this non-randomized, single-group study. It therefore does not provide a like-for-like comparison with another treatment or with no treatment.
Primary question
What was the rate of major bleeding during the treatment period, from the first study drug injection up to Day 17, among participants included in the primary endpoint population?
The study record describes an evaluation of fondaparinux for prevention of venous thromboembolism after hip fracture surgery. Its stated primary endpoint, however, is the rate of major bleeding during treatment. The endpoint description also refers to signs and symptoms suggestive of venous thromboembolic events, venography, and central adjudication. The registry record does not provide a numeric primary endpoint result, so the observed bleeding rate and its precision cannot be described from this record.
The record lists secondary outcomes covering pulmonary embolism, deep vein thrombosis, proximal and distal-only deep vein thrombosis, bleeding, adverse events, serious adverse events, death, and transfusion. It reports no analyses. The study can therefore be described as a single-group assessment with a stated safety endpoint and additional listed outcomes, but the registry record does not show results for those efficacy outcomes or explain how the listed outcomes were analyzed.
3. Trial Design
This was a Phase 3, completed, non-randomized, unmasked, single-group study of fondaparinux sodium after hip fracture surgery. The registry lists an enrollment of 48. The intervention is identified as fondaparinux, and the safety record names the group as Fondaparinux Sodium 2.5 mg s.c. There is no concurrent control group, so the design is not a randomized comparison and does not support a direct treatment contrast within the study.
The study began on 2006-02-16, and its primary completion date was 2006-10-26. Its stated purpose was to evaluate fondaparinux in prevention of venous thromboembolism after hip fracture surgery. The registry brief summary says the study was requested by PMDA to confirm efficacy and safety for HFS. The study status is completed. These record details describe the study’s administrative and design context, but do not substitute for outcome results.
The primary outcome was the rate of major bleeding during the treatment period, defined as extending from the first study drug injection up to Day 17. Intended treatment began 24±2 hours after surgical closure. The endpoint population is described as a full analysis set that excluded participants who did not receive study drug and participants without valid efficacy data, with no evaluable venogram given as an example. The registry record does not report how many participants met each exclusion or how many contributed to the primary endpoint.
Eleven outcome measures are listed, but the registry reports zero analyses. That means the record does not provide an inferential analysis to evaluate alongside the design description. The allocation and masking details also matter for interpretation: without random allocation or a comparator, outcome rates cannot separate the effects of treatment from other influences or provide a controlled estimate of relative benefit or harm.
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
| Stage | Fondaparinux Sodium 2.5 mg s.c. |
|---|---|
| STARTED | 48 |
| COMPLETED | 42 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Fondaparinux Sodium 2.5 mg s.c. |
|---|---|
| Adverse Event | 3 |
| Other | 3 |
Analysis population for the primary outcome, as defined in the registry: Full analysis set used which consisted of all participants who were assigned to study drug with the exception of those who did not receive study drug at all and those with no valid efficacy data (example no evaluable venogram).
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.
| Characteristic | Unit | Fondaparinux Sodium 2.5 mg s.c. |
|---|---|---|
| Participants analysed | 48 | |
| Age, Continuous | Years | 76.6 (SD 14.4) |
| Sex: Female, Male: Female | Participants | 40 |
| Sex: Female, Male: Male | Participants | 8 |
| Region of Enrollment: Japan | Participants | 48 |
6. Primary Endpoint
The registry lists the primary outcome as Rate of Major Bleeding During Treatment Period, measured over From the first study drug injection up to Day 17.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | % of normalized events per participant |
| Endpoint classification | Event-Rate Endpoint |
The primary endpoint is the rate of major bleeding during the treatment period, from the first study drug injection up to Day 17. The record defines rate as the number of events divided by the number of participants evaluated, multiplied by 100. Thus, the reported measure is a percentage based on events and evaluated participants, rather than a rate based on person-time. The registry labels the unit as “% of normalized events per participant.”
Bleeding is a safety outcome, so measuring it alongside the study’s stated focus on prevention of venous thromboembolism reflects the need to assess potential harm as well as the intended clinical context. The registry record lists a 95% confidence interval as the endpoint’s dispersion measure, but gives neither the endpoint estimate nor its interval. It also does not report the criteria used to classify a major bleeding event, so the classification definition cannot be further described from this record.
The endpoint description mentions symptoms suggestive of venous thromboembolism and says those events were adjudicated by the Central Independent Adjudication Committee of Efficacy. It also describes venography obtained no later than two calendar days after the last study drug administration, between Day 11 and 17. These details concern assessment and adjudication described in the record; they do not supply the missing major-bleeding result. The recorded endpoint can therefore be identified and its stated calculation explained, but its observed frequency and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies major bleeding during treatment as the primary endpoint and states that the intended summary was a rate with a 95% confidence interval. However, it does not report the primary endpoint estimate or the interval. Consequently, the posted results do not establish how often major bleeding occurred in the endpoint population or how precise an estimate would be. No numerical conclusion about the primary endpoint can be drawn from the record.
The safety information lists 2 serious adverse event participants among 48 at risk in the fondaparinux group, 37 participants with other adverse events among 48 at risk, and 0 deaths. The listed serious-event terms are ileus and femur fracture, each reported as 2.1%. These are descriptive registry entries. The record does not state whether events were judged related to treatment, whether participants could contribute more than one event, or how the serious-event terms relate to the overall serious adverse event count. The figures should not be treated as a comparative estimate of treatment risk.
The absence of a comparator is central to interpreting all outcomes. A single-group result, even if fully reported, would describe outcomes in the study group but would not show what would have occurred under a different treatment or without study treatment. Non-randomized allocation also means that there is no randomization-based balance between treatment groups to support a causal contrast. This study record therefore does not supply comparative evidence about the effect of fondaparinux.
The record lists secondary outcomes for pulmonary embolism, deep vein thrombosis, bleeding, adverse events, death, and transfusion. It reports zero analyses, and no numerical results for these outcomes are included in the record. Their presence in the outcome list indicates what was planned or tracked in the registry, not what was observed. Likewise, an outcome’s title alone does not establish its definition, denominator, estimate, or uncertainty.
The study was completed and lists enrollment of 48, but enrollment is not necessarily the number evaluated for each outcome. The primary endpoint population excludes participants without study drug exposure and those without valid efficacy data. The number actually evaluated for the primary endpoint is not reported in the registry record. Without the estimate, interval, and outcome-specific denominator, neither the magnitude nor precision of the primary result can be assessed. These limits are especially important because the study has no control arm and does not post an analysis plan or results in the registry record.
9. Statistical Methods Explained
What does the endpoint rate represent?
In general, an event rate summarizes the occurrence of an outcome in a defined population or over a defined period. In this record, the primary endpoint rate is explicitly defined as the number of events divided by the number of participants evaluated, multiplied by 100. It is therefore expressed as a percentage using participants as the denominator. This differs from a person-time rate, which uses accumulated time at risk as its denominator. The record’s label “% of normalized events per participant” should be read together with its stated formula; the registry does not provide further detail about normalization.
When a measure counts events rather than only whether each participant had an event, repeated events may affect the numerator. The endpoint description does not clarify whether repeat events were possible or how they were handled. The actual primary endpoint estimate is not reported in the registry record, so neither its numerator nor evaluated denominator can be checked.
What does a confidence interval communicate?
In general, a confidence interval expresses the statistical precision of an estimate under the assumptions of the method used to calculate it. A narrower interval indicates greater precision than a wider interval, while an interval that spans a broad range leaves greater uncertainty about the underlying rate. A confidence interval is not a guarantee that the true value lies within a particular interval. The registry identifies a 95% confidence interval as the dispersion measure for the primary endpoint, but reports no interval limits or point estimate. The calculation method and any assumptions used for that interval are not reported in the registry record.
Why does the study design shape the interpretation?
In general, random allocation can make treatment groups more comparable by distributing measured and unmeasured baseline characteristics through chance. This study was non-randomized and single-group, with no comparator. Its results, if reported, would describe outcomes observed among participants in the study group. They would not offer a within-trial comparison that isolates a treatment contrast. Differences between observed outcomes and an external expectation could reflect factors other than treatment, and the registry does not give an external comparison or adjustment strategy.
The study was also unmasked. In general, masking can reduce the influence of knowledge about treatment assignment on care, reporting, assessment, or adjudication. The record does state that venous thromboembolic events were adjudicated by a Central Independent Adjudication Committee of Efficacy. It does not say whether adjudicators were masked, or how masking was handled for the major bleeding endpoint. No additional conclusion about bias control can be drawn from the record.
How should the analysis population be understood?
The primary endpoint population is described as a full analysis set. It includes participants assigned to study drug except those who received no study drug and those with no valid efficacy data, with an unevaluable venogram given as an example. In general, excluding participants after assignment can affect the interpretation if the excluded participants differ systematically from those analyzed. The record does not report the number excluded, the reasons for exclusions beyond the examples, or whether the primary endpoint denominator differs from enrollment.
The registry lists enrollment of 48 and lists 48 at risk in the adverse-event record. Those figures are not sufficient to establish the number evaluated for the primary endpoint or for each secondary outcome. Outcome-specific denominators and missing-data handling are not reported in the registry record.
What can be learned from the posted safety summaries?
In general, adverse event summaries are descriptive counts of participants or events meeting specified definitions. Serious adverse events and other adverse events are separate categories in the record, but their definitions and overlap are not elaborated in the posted registry entries. The listed figures should not be added together: the record does not establish whether categories overlap or whether the counts represent unique people across outcomes. Nor should the serious-event term percentages be interpreted as comparative risks; there is no comparator group, and the method behind those percentages is not described.
The record lists a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation as assumptions for planning illustrations computed from an observed effect. Those are generic planning assumptions, not evidence that this single-group study used a two-arm test. The record gives no observed primary effect or analysis results, and the planning assumptions do not establish the trial’s own design rationale or observed power. The trial’s sample-size justification and statistical analysis plan are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists eleven outcome measures, including the primary major-bleeding endpoint and secondary outcomes for pulmonary embolism, deep vein thrombosis, bleeding, adverse events, death, and transfusion. When a study evaluates multiple outcomes, the chance of at least one apparently unusual result can increase if many statistical tests are conducted without an adjustment or a prespecified hierarchy. In general, multiplicity methods address that issue, but the registry record does not report whether any were planned or used. It also reports zero analyses, so no result-specific multiplicity approach can be assessed.
The record does not report a statistical analysis plan, a hierarchy for secondary outcomes, or a strategy for interpreting multiple comparisons. The primary endpoint is named, but the record alone does not show how it was prioritized analytically or whether the secondary outcomes were intended as confirmatory or descriptive. No assumptions about those choices should be inferred from the outcome list.
For the primary endpoint, the stated analysis population excludes participants who did not receive study drug and those without valid efficacy data, such as an unevaluable venogram. The number of excluded participants, the extent of missing endpoint data, and any imputation or sensitivity analyses are not reported in the registry record. Outcome-specific denominators are also not reported. These omissions limit assessment of how incomplete data may affect the endpoint estimate.
Because allocation was non-randomized and there was a single group, missing-data concerns are only part of the interpretive limits. There is no concurrent comparison, and no adjustment model or covariate strategy is reported. The record therefore does not permit evaluation of either a multiplicity procedure or an adjusted analysis.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Fondaparinux Sodium 2.5 mg s.c. | 2 | 48 | 4.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Fondaparinux Sodium 2.5 mg s.c. | 0 of 48 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Fondaparinux Sodium 2.5 mg s.c. | 37 of 48 |
Most frequent serious adverse event terms
| Event term | Organ system | Fondaparinux Sodium 2.5 mg s.c. |
|---|---|---|
| Ileus | Gastrointestinal disorders | 1 of 48 |
| Femur fracture | Injury, poisoning and procedural complications | 1 of 48 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Fondaparinux Sodium 2.5 mg s.c. |
|---|---|---|
| Constipation | Gastrointestinal disorders | 8 of 48 |
| Insomnia | Psychiatric disorders | 8 of 48 |
| Oedema peripheral | General disorders | 4 of 48 |
| Excoriation | Injury, poisoning and procedural complications | 4 of 48 |
| Dermatitis contact | Skin and subcutaneous tissue disorders | 4 of 48 |
| Restlessness | Psychiatric disorders | 3 of 48 |
| Pyrexia | General disorders | 3 of 48 |
| Blood alkaline phosphatase increased | Investigations | 3 of 48 |
| Abdominal pain upper | Gastrointestinal disorders | 2 of 48 |
| Diarrhea | Gastrointestinal disorders | 2 of 48 |
Serious events with the highest arm-level rate: ileus (2.1%), femur fracture (2.1%).
The safety record lists 2 serious adverse event participants among 48 at risk in the fondaparinux sodium group. It lists 37 participants with other adverse events among 48 at risk and 0 deaths. Ileus and femur fracture are the serious-event terms shown, each reported as 2.1%. These figures are descriptive entries for the study group, not comparisons between treatments.
The registry does not state whether serious adverse events were considered related to fondaparinux, whether the listed terms were mutually exclusive, or whether a participant could have more than one event. It also does not explain the relationship between the serious-event count and the term-specific percentages. The counts should not be summed or treated as counts of unique events beyond what the record explicitly says.
In general, adverse-event frequency and seriousness do not by themselves establish causation. Assessing a treatment relationship requires information about timing, clinical context, alternative explanations, and the study’s attribution procedures. Those details are not reported in the registry record. Because the study had no comparator, the safety figures cannot show whether the observed events were more or less frequent than under another treatment or no study treatment.
12. What the Result Does, and Does Not, Mean
The registry record describes a completed single-group study of fondaparinux after hip fracture surgery, with major bleeding named as the primary endpoint and a range of venous thromboembolic and safety outcomes listed. It also gives a treatment period and a definition of the primary rate. These details explain what the study set out to assess, but the record does not include the primary endpoint estimate, its 95% confidence interval, or numerical results for the listed secondary outcomes.
The safety entries report serious adverse events, other adverse events, and deaths in the study group. They are not controlled comparisons and do not establish that fondaparinux caused or prevented any particular event. The non-randomized, single-group design cannot distinguish treatment effects from other influences on outcomes. Even a complete set of single-group event rates would not answer the comparative question of what outcomes would have been under an alternative treatment.
The registry’s stated purpose refers to efficacy and safety evaluation, but purpose is not evidence of a result. The listed outcomes likewise do not establish that a particular outcome occurred or was absent. Because the record reports zero analyses and omits endpoint results, the magnitude and precision of the primary outcome cannot be judged. The record also does not report the statistical plan, missing-data handling, or the sample-size justification.
Accordingly, the appropriate reading is limited: the record establishes the design, intervention, endpoint definition, outcome list, and selected safety counts. It does not provide enough outcome information to determine the observed major-bleeding rate, assess its uncertainty, or compare the intervention with another approach. No clinical recommendation follows from these registry entries alone.
13. Why This Trial Matters Statistically
This trial is statistically notable because its stated primary endpoint is a safety outcome, major bleeding, within a study whose title and summary concern prevention of venous thromboembolism after hip fracture surgery. Evaluating both efficacy-related outcomes and safety outcomes is a common challenge in clinical research: outcomes can differ in importance, frequency, and the way they are measured. The registry lists several such outcomes, but does not provide their results or an analysis plan.
The single-group, non-randomized design is also important. It can describe the experience of participants receiving the study drug, but does not create a concurrent counterfactual group for estimating a comparative treatment effect. This distinction is essential when interpreting any observed event count: a number of events describes what was recorded in the group, not what treatment caused.
The primary endpoint definition emphasizes denominator choice and assessment timing. It specifies a percentage based on events and evaluated participants, identifies the treatment period through Day 17, and describes central adjudication of venous thromboembolic events. These details show why endpoint definitions matter: a rate’s interpretation depends on what counts as an event, who is included in the denominator, and the period over which events are collected. Yet the record does not report the primary estimate or the number evaluated, preventing a full statistical appraisal.
Finally, the discrepancy between a stated set of outcomes and the absence of posted analyses highlights the distinction between registering an outcome and reporting its result. Without estimates, uncertainty measures, analysis details, and a comparator, readers cannot evaluate the strength of evidence for the study’s efficacy or safety questions. The record remains informative about design and measurement, while leaving the central outcome interpretation unresolved.
14. 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 most direct limitation of the registry record is that it does not report the primary endpoint result or its stated 95% confidence interval. Although the primary endpoint definition and treatment period are described, the numerator, evaluated denominator, and resulting estimate are absent. The registry also reports zero analyses, and numerical results for the listed secondary outcomes are not included.
The study is non-randomized and single-group, with no concurrent comparator. As a result, it cannot provide a controlled estimate of differences in bleeding or venous thromboembolic outcomes between fondaparinux and another approach. The absence of masking is another design feature, while the record does not clarify whether outcome assessors or adjudicators were masked. Central adjudication is mentioned for venous thromboembolic events, but the record does not establish that it applied to the primary bleeding endpoint.
The enrolled population is listed as 48, but the primary analysis population excludes participants with no study drug exposure or no valid efficacy data. The number evaluated for the endpoint and the number excluded are not reported in the registry record. Missing-data procedures, the sample-size justification, the statistical analysis plan, and any adjusted analyses are also not reported. These details are needed to assess precision, potential selection effects, and analytic choices.
The record does not explain the criteria for major bleeding, the handling of repeated events, or the relationship between serious adverse event counts and term-specific entries. Safety attribution to treatment is not reported. Together, the absent outcomes and methodological details constrain interpretation beyond the limitations inherent in the single-group design.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Hip Fracture Study of GSK576428 (Fondaparinux Sodium) — NCT00320424.
- Registry record last updated 2018-09-04; status last verified 2018-08.
- Results first posted 2017-10-11.
- 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.
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18. Record Summary
NCT00320424 is a completed Phase 3, non-randomized, unmasked, single-group study of fondaparinux sodium after hip fracture surgery. The registry lists enrollment of 48 and names the rate of major bleeding during treatment as the primary endpoint, with a 95% confidence interval as its dispersion measure. The endpoint period extends from the first study drug injection up to Day 17.
The record lists eleven outcome measures and zero analyses. It gives selected safety entries, including serious adverse events, other adverse events, deaths, and serious-event terms. It does not report the primary endpoint estimate, its confidence interval, or numerical results for the listed secondary outcomes. As a single-group study without randomization or a concurrent comparator, it does not provide a controlled treatment comparison. The record’s design and endpoint definitions can be described, but its efficacy and primary safety results cannot be assessed from the registry record.