Safety Study of Desirudin, an Anticoagulant for the Prophylaxis of Thrombosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Study of Desirudin, an Anticoagulant for the Prophylaxis of Thrombosis (NCT00913133), a na phase 4 study. The primary outcome is Major Bleeding.

2. Clinical Question

Thus, the record describes a safety-focused question in people treated with desirudin, while its stated objective concerns prophylaxis of thrombosis. Without a control group or reported outcome analysis, it cannot establish how outcomes compare with heparin-based treatment or another strategy. The primary endpoint definition identifies events of substantial clinical severity, but no observed primary endpoint result is available in the registry record.

3. Trial Design

This is a completed Phase 4, single-group trial of desirudin. The registry record lists enrollment of 516 and describes the intervention as desirudin 15 mg twice daily for a minimum of 5 days. The trial objective was to demonstrate the clinical utility of fixed-dose subcutaneous desirudin for thrombosis prophylaxis as an alternative to heparin-based anticoagulation. Its condition is thrombosis.

The study started in 2010-03, had primary completion in 2011-06, and is listed as completed. Masking is listed as none, allocation as NA, and the model as single-group. These entries indicate that the record does not describe a masked or randomized comparison. It does not provide details of treatment assignment beyond the single-group designation, or additional information about treatment adherence and follow-up.

The stated primary outcome is major bleeding, measured in participants, with a timeframe of 24 hours after the last dose of study drug. The primary outcome population is all patients receiving at least one dose. Thrombosis is listed as a secondary outcome. The record notes two outcome measures but no analyses. It does not report a comparator group, a statistical analysis plan, or an analysis population for the secondary outcome.

Because this is not a randomized comparison, the trial design cannot separate treatment-associated outcomes from background risk or other influences using an internal control group. The regimen and safety outcomes can be described as reported, but comparative effectiveness or safety against heparin-based anticoagulation is not established by the design details 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

Analysis population for the primary outcome, as defined in the registry: All patients receiving at least one dose of study drug

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 Major Bleeding, measured over 24 hours after last dose of study drug.

The primary endpoint is major bleeding, counted as participants, with assessment through 24 hours after the last dose of study drug. Its population is all patients who received at least one dose. The definition targets clinically important hemorrhage: clinically evident bleeding associated with a hemoglobin decrease of at least 2 g/dL that leads to transfusion of at least 2 units of whole blood or packed red cells outside the peri-operative period, or bleeding that is intracranial, retroperitoneal, or into a prosthetic joint. The peri-operative period is defined as the time from the start of surgery or a procedure through 12 hours after it.

Such a definition is used to focus an outcome on events with substantial clinical consequences rather than treating every report of bleeding as equivalent. Counting participants makes the endpoint a binary outcome: each person either meets the stated definition during the specified timeframe or does not. The timeframe also clarifies which period of observation contributes to the endpoint.

The registry record does not report the number of participants meeting this definition, an estimate of its frequency, or an uncertainty interval. It therefore describes how the endpoint should be interpreted but does not provide the primary endpoint result. The endpoint definition alone cannot establish how often major bleeding occurred in the trial.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry record is sparse. It identifies the primary endpoint as a participant count and classifies the outcome data as binary. It reports no analyses. The design is single-group, rather than a randomized comparison, and the registry record does not describe an inferential analysis plan. The explanations below distinguish the general statistical ideas from the particular information available for this study.

What does a binary participant outcome represent?

In general, a binary endpoint records whether each participant experienced the event specified by the endpoint definition during the relevant observation period. A count of affected participants is the number who met that definition. For major bleeding, the definition includes specified clinical and laboratory features, and the timeframe extends through 24 hours after the last dose. The registry record gives these rules but does not report the resulting count.

Binary outcomes can be described with counts and proportions. A proportion needs both an event count and a clearly defined denominator. The record states that the primary population is all patients receiving at least one dose and separately lists enrollment of 516, but it does not report the primary event count or additional details linking the outcome population to the enrollment figure. No primary endpoint proportion can therefore be stated from the record.

What can a confidence interval tell a reader?

In general, a confidence interval expresses the uncertainty around an estimated quantity under the assumptions of the analysis. For a binary outcome, it can describe how precisely an event proportion or a comparison is estimated. A narrow interval indicates greater precision under the method used; a wide interval indicates less precision. An interval does not correct for design limitations, missing outcome information, or bias. The registry record does not report a confidence interval for major bleeding or the listed adverse-event counts.

What does the single-group design permit?

A single-group summary can describe outcomes recorded in the treated group. It does not, by itself, estimate a contrast with a separate control group. In a randomized comparison, random assignment can support causal interpretation of a treatment contrast when the trial is conducted and analyzed appropriately. Here, allocation is NA and the model is single-group. No like-for-like control comparison is described, so the stated objective of considering desirudin as an alternative to heparin-based anticoagulation should not be read as a measured comparative effect.

Without a comparator, outcome frequencies may reflect treatment, participants' underlying clinical circumstances, care practices, and other influences. A descriptive count does not disentangle those influences. This is a general feature of uncontrolled designs, not a conclusion about the cause of any event in this particular trial.

How should the planning illustration be understood?

The record characterizes its sample-size calculations as planning illustrations based on the observed effect, not as the trial's own design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, the described output is participants per arm for the specified power. These assumptions describe a hypothetical planning exercise, not the actual single-group design.

Such sample-size calculations generally ask how many participants a future comparative study might require to detect a chosen effect under specified assumptions. Their outputs depend on the assumed effect and analysis method. They are not observed power, and they do not show that the completed trial was adequately powered for its own objective. The registry record does not report a protocol-based sample-size justification. The observed effect and calculated planning values are not reported in the registry record, so no planning figure can be interpreted.

What is not available for recalculation?

A recalculation from summary statistics requires the relevant observed outcome values and a suitable analysis specification. For major bleeding, the registry record lacks the event count. It also reports no analysis for the listed outcomes. Consequently, there is no posted primary estimate to check or reproduce, and no adjusted or unadjusted treatment contrast to recalculate. No statistical significance conclusion can be drawn from a result that is not reported.

In general, a recalculated result based on aggregate counts would be an unadjusted analysis and could differ from a sponsor's prespecified analysis if the latter used different populations, adjustment variables, or methods. No sponsor analysis is reported for this endpoint, so there is no analysis to compare with a recalculation. A planning illustration should also remain separate from an observed treatment result: it describes assumptions about a possible study, not evidence about what happened to participants.

Finally, over-dispersion is a general issue for count outcomes when variability exceeds what a simple model assumes. It can affect standard errors and uncertainty estimates. The primary endpoint is described as a binary participant count, not an event-rate model, and the registry record does not specify an over-dispersion adjustment or an analysis that would call for one. A methods explanation cannot substitute for the unreported analysis.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Desirudin")
n      <- c(516)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Desirudin  516  0  0.0  0.0  0.7  0.0  0.7  0.0  0.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures, identifies major bleeding as the primary outcome, and lists thrombosis as a secondary outcome. It reports no analyses. It does not describe a hierarchy of secondary outcomes, a multiplicity adjustment, or a plan for controlling the chance of false-positive findings across multiple tests. Whether such procedures were specified or used is not reported in the registry record.

Multiplicity matters when several outcomes or comparisons are tested: considering many results can increase the chance that at least one appears statistically notable by chance. In general, an analysis plan can address this through prespecified outcome priorities or statistical adjustments. The lack of a reported analysis means there is no basis to assess whether multiplicity was addressed. The number of outcome measures alone does not show how many statistical tests were planned or performed.

Missing-data handling is also not reported in the registry record. The primary population is defined as all patients receiving at least one dose, but the record does not state whether every participant in that population had ascertainable endpoint status, how incomplete follow-up was treated, or whether any imputation or sensitivity analysis was used. Those details affect interpretation when outcome status is unknown.

The record does not describe an intention-to-treat analysis, a per-protocol analysis, or another analysis population beyond the primary outcome population definition. It also does not provide a flow of participants through treatment and follow-up. Without these details and the event counts, readers cannot assess the impact of missing outcomes, departures from treatment, or differences between analysis populations.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: small intestinal obstruction (1.4%), atrial fibrillation (1.0%), postoperative ileus (1.0%), renal failure acute (1.0%), acute myocardial infarction (0.8%).

The registry record lists 80 participants affected by serious adverse events among 516 at risk, and 382 affected by other adverse events among 516 at risk. The entries are counts, not comparative effects. Because the trial is single-group and no comparator is described, these figures do not establish whether adverse events were more or less frequent than under another treatment.

The listed serious adverse-event terms are small intestinal obstruction at 1.4%, atrial fibrillation at 1.0%, postoperative ileus at 1.0%, renal failure acute at 1.0%, acute myocardial infarction at 0.8%, and gastric hemorrhage at 0.8%. These are selected terms in the registry record, not a complete description of every safety outcome. The record does not explain the denominator or coding rules for each term in the listed summary, so these percentages should be read as reported rather than independently interpreted as rates for a new population.

The major-bleeding endpoint has a separate clinical definition and timeframe. The adverse-event counts do not reveal how many participants met that definition. Deaths are not reported in the registry record. These safety summaries describe reported events, but their scope and lack of a control group limit comparative conclusions.

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

The result supported by the registry record is a description of a completed, single-group desirudin study, its treatment regimen, its major-bleeding endpoint definition, and the adverse-event counts recorded. The record does not report the primary major-bleeding count, an estimate of its frequency, or an inferential analysis. It also does not report analyses for thrombosis, which is listed as a secondary outcome.

This absence means that the primary outcome cannot be interpreted as showing a particular frequency or level of precision. It does not establish that no major bleeding occurred; it means the outcome result is not reported in the registry record. Similarly, the listed serious and other adverse-event counts are descriptive and do not show whether desirudin changed risk relative to an alternative.

The trial objective frames desirudin as an alternative to heparin-based anticoagulation, but no heparin-based comparator is described. The study therefore cannot provide a direct randomized comparison of the two approaches. A single-group safety summary can be useful for describing events observed in treated participants, but it cannot isolate the effect of treatment from other possible explanations for those events.

The registry record also does not report confidence intervals, p values, a statistical analysis plan, or missing-data methods. Without those elements, statistical precision and the robustness of any outcome analysis cannot be evaluated. The completed status indicates the study is recorded as completed; it does not supply missing outcome results.

In short, the record establishes what question the trial set out to address and how the primary endpoint was defined, alongside limited descriptive safety information. It does not establish comparative benefit, comparative risk, or a definitive primary endpoint result. These limits concern what the registry record reports and should not be mistaken for evidence that an outcome did or did not occur.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between an objective and a design capable of answering it. The stated objective concerns desirudin as an alternative to heparin-based anticoagulation. Yet the registry record describes a single-group study, with allocation listed as NA and no comparator arm. That design can describe outcomes among treated participants, but it does not estimate a direct treatment contrast.

The record also illustrates why a precise endpoint definition is not the same as a reported endpoint result. Major bleeding is defined using clinical criteria, a hemoglobin decrease, transfusion criteria, specific anatomical events, and a specified observation window. Such detail helps readers understand what an event would mean. However, without the outcome count or analysis, the definition alone says nothing about how often the endpoint occurred or how precisely it was estimated.

Safety summaries also require attention to their scope. Serious adverse events, other adverse events, and the specifically defined primary endpoint are not interchangeable categories. Their counts should not be merged or interpreted as if they answer the same question. The registry record does not provide enough information to map the broader safety summaries to the major-bleeding endpoint.

Finally, the described sample-size calculations are planning illustrations, not evidence that the trial had a particular observed power or that its design was justified by those calculations. Separating descriptive observations, comparative estimates, and planning assumptions is central to sound statistical interpretation. This record makes those distinctions especially important because its primary outcome analysis is not reported.

15. 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 main limitation for interpretation is that the registry record does not report the primary major-bleeding outcome count or analysis. Although the endpoint definition and timeframe are specified, there is no event estimate or confidence interval from which to judge its observed frequency or precision. Thrombosis is listed as a secondary outcome, but its result is also not reported in the registry record.

The single-group design limits comparative interpretation. Allocation is listed as NA, masking as none, and no control arm is described. Outcomes among desirudin recipients therefore cannot be directly contrasted with outcomes under heparin-based anticoagulation using this record. The stated alternative-treatment objective should not be mistaken for a comparative finding.

Reporting about outcome ascertainment and analysis is limited. The registry record does not describe missing-data methods, follow-up completeness, statistical analysis methods, multiplicity procedures, or an analysis population beyond the primary population definition. It also does not report demographic or clinical details that would help characterize the enrolled population. Whether these details were included in other study materials is not reported in the registry record.

The safety information is descriptive. The record reports serious and other adverse-event counts and selected serious-event terms, but does not provide a comparator or uncertainty estimates. It does not report deaths. The listed adverse-event summaries should not be used to infer the major-bleeding endpoint, whose definition is distinct.

These limitations do not demonstrate that the study was poorly conducted; they identify what cannot be assessed from the registry record. In particular, completion status and a stated clinical objective do not replace outcome reporting, a comparator, or a transparent analysis plan.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Study of Desirudin, an Anticoagulant for the Prophylaxis of Thrombosis — NCT00913133.
• Registry record last updated 2013-01-10; status last verified 2013-01.
• Results first posted 2013-01-03.
• 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.

19. Record Summary

The registry record describes NCT00913133, a completed Phase 4, single-group study of desirudin for thrombosis prophylaxis. Enrollment was 516. The intervention was desirudin 15 mg twice daily for a minimum of 5 days. The study started in 2010-03, with primary completion in 2011-06.

The primary outcome was major bleeding among patients receiving at least one dose, assessed through 24 hours after the last dose. Thrombosis was listed as a secondary outcome. The record reports no analyses and does not report the primary endpoint result. It lists 80 participants affected by serious adverse events and 382 affected by other adverse events, each among 516 at risk, along with selected serious-event terms.

The single-group design does not provide a concurrent comparison with heparin-based anticoagulation. Missing-data methods, multiplicity handling, and the statistical analysis plan are not reported in the registry record. The available information supports a description of the design and reported safety counts, but not a comparative conclusion or a quantified primary endpoint result.