Safety and Efficacy of Turoctocog Alfa in Haemophilia A Subjects: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Turoctocog Alfa in Haemophilia A Subjects (NCT00840086), a non-randomized phase 3 study. The primary outcome is The Incidence Rate of FVIII Inhibitors (Greater Than or Equal to 0.6 Bethesda Units (BU)).

2. Clinical Question

Statistically, this is a single-group assessment rather than a comparative-effectiveness trial. Its primary question concerns inhibitor occurrence during treatment, while the trial's broader stated aims include safety and efficacy in preventing and treating bleeds. The record also lists frequency of adverse events as a secondary outcome. It does not report a separate numerical efficacy result in the registry record.

3. Trial Design

The registry identifies this as a phase 3, non-randomized, open-label, single-group trial of turoctocog alfa in subjects with haemophilia A. It describes a main trial and a sub-trial. The main trial investigated safety and efficacy in prevention and treatment of bleeds; the sub-trial investigated prevention and treatment of bleeding episodes during surgical procedures. The trial was conducted in Asia, Europe, and North and South America.

The record lists an enrollment of 150 and describes the safety analysis set as all 150 subjects who received at least one dose. These figures describe the registered enrollment and treated safety population; they do not establish a randomized or controlled comparison. The primary endpoint analysis used a defined population based on exposure days and inhibitor status. The record states that 148 subjects had 50 exposure days and that the analysis included all subjects with at least 50 exposure days and/or with inhibitors.

Because the study was open-label, treatment assignment was not masked. Because it was non-controlled and single-group, there was no concurrent comparator arm against which to estimate a treatment contrast. The registry does not report a control condition, random allocation, or blinded outcome assessment. This design can describe observed outcomes among treated subjects, but it cannot by itself separate treatment-associated outcomes from background risk, changes over time, or other influences.

The registry lists the trial status as completed. The recorded start was 2009-04 and primary completion was 2011-09. The record does not report the protocol rationale for the enrollment target, the planned duration for each subject, or details of recruitment and follow-up beyond the endpoint timeframe description. Those design 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: The safety analysis set includes all 150 subjects who received at least one dose of the investigational product. The analysis of the primary endpoint included all subjects with at least 50 exposure days and/or with inhibitors. A total of 148 subjects had 50 exposure days (EDs).

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 The Incidence Rate of FVIII Inhibitors (Greater Than or Equal to 0.6 Bethesda Units (BU)), measured over The adverse events were collected throughout the trial, corresponding to an average of 188 days per subject..

The primary endpoint is the incidence rate of FVIII inhibitors at a threshold of at least 0.6 Bethesda Units (BU). Inhibitors are antibodies that can reduce the activity of administered factor VIII; counting their occurrence is therefore a safety-focused way to monitor an immune response during factor VIII treatment. The endpoint is expressed as the number of subjects with inhibitors relative to a defined exposure-based population.

The endpoint description says that the numerator includes all patients with inhibitors. Its denominator includes patients with a minimum of 50 exposure days, along with any patients who had fewer exposure days but developed inhibitors. The analysis population is correspondingly described as subjects with at least 50 exposure days and/or with inhibitors. The record states that 148 subjects had 50 exposure days.

This definition matters for interpretation: the measure is not simply a proportion among all treated subjects, nor is it described as an event rate per person-time. Exposure days provide a treatment-exposure criterion, while the inclusion of inhibitor cases with fewer exposure days is intended to retain those cases in the endpoint calculation. The adverse events timeframe is described as throughout the trial, corresponding to an average of 188 days per subject.

The registry gives the endpoint definition but does not report the numerical number of inhibitor cases or the resulting endpoint estimate. Its precision, including any confidence interval, is also not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods described in the registry are limited. The record identifies a single-group, non-randomized, open-label phase 3 trial and defines the primary endpoint population and calculation rule. It does not report a detailed statistical analysis plan, a model for the primary outcome, a confidence interval method, or a missing-data procedure. The explanations below distinguish the endpoint's stated calculation from general statistical concepts; they do not imply that unreported methods were used.

What does an exposure-based endpoint capture?

The primary measure concerns the occurrence of FVIII inhibitors above the stated threshold of at least 0.6 Bethesda Units (BU). Exposure days reflect how long participants received treatment in terms of treatment exposures, rather than simply elapsed calendar time. Requiring a minimum exposure helps define a group with meaningful treatment exposure for assessing inhibitor occurrence. The endpoint description also retains inhibitor cases with fewer than 50 exposure days by including them in its denominator.

That rule means the endpoint should be interpreted according to its stated population definition, not as a crude count divided by all treated subjects. The record specifies that all patients with inhibitors enter the numerator and that the denominator includes those with a minimum of 50 exposure days plus any inhibitor cases with fewer exposures. It does not report the numerical numerator, the final denominator, or the resulting estimate. The description calls the measure an incidence rate, but its stated unit is a count of subjects relative to a count of subjects meeting exposure criteria; it is not described as a rate per person-time.

Why does the analysis population matter?

An analysis population determines which participants contribute to an estimate. Here, the safety set is described as all 150 subjects who received at least one dose. The primary endpoint analysis includes all subjects with at least 50 exposure days and/or with inhibitors. The record states that 148 subjects had 50 exposure days. These definitions serve different purposes, so the safety-set size should not be substituted for the primary endpoint denominator.

In general, clearly defining an analysis population makes it possible to understand which observations an estimate represents. Including inhibitor cases with fewer exposure days may be important because excluding them solely for lower exposure would omit events relevant to the endpoint. The registry does not give individual exposure information or a subject-level accounting that would allow the endpoint denominator to be reconstructed.

How should uncertainty be understood?

General statistical explanation: an estimate describes the observed data, while a confidence interval describes a range of values compatible with those data under the method's assumptions. A narrow interval generally indicates greater precision than a wide interval, but neither an estimate nor its interval resolves bias from an uncontrolled design. No confidence interval or other uncertainty measure for the primary endpoint is reported in the registry record.

The record describes adverse events as collected throughout the trial, corresponding to an average of 188 days per subject. An average follow-up description does not show that every subject had the same observation time. General explanation: when people contribute different amounts of time at risk, analyses may need to account for that difference, especially for event rates based on person-time. The registry's primary endpoint definition is exposure-based and does not report a person-time model.

What can be inferred from a single-group design?

General statistical explanation: randomization can help balance measured and unmeasured characteristics between comparison groups, while a concurrent control can provide a reference for outcomes over the same period. This trial is described as non-randomized and non-controlled, so neither feature is available for a treatment contrast. The observed treated-group data can describe what was recorded among participants, but cannot alone estimate the difference that would have occurred against a control group.

The record states that the trial was open-label. General explanation: knowledge of treatment assignment can affect behavior, reporting, or assessment, depending on the outcome and how it is measured. The registry does not describe blinded endpoint assessment or further safeguards against such influences. It also does not report a statistical model or adjustment procedure, so no adjusted treatment effect should be inferred.

Are the sample-size illustrations trial power?

The sample-size material is described as a planning illustration computed from the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such an illustration is not the trial's original design calculation, and it is not observed power. This trial itself is registered as a single-group study, so the equal-allocation comparison is hypothetical rather than its treatment assignment. The registry does not report the protocol's sample-size justification.

General explanation: power calculations describe the chance of detecting an assumed effect under specified design and analysis assumptions. They are planning tools, not evidence that an effect exists, and post hoc calculations do not make a non-controlled study comparative. No sample-size illustration can replace the missing numerical primary endpoint result or its uncertainty in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists the incidence rate of FVIII inhibitors as the primary outcome and frequency of adverse events as a secondary outcome. It does not report a multiplicity strategy, such as a prespecified adjustment across several outcomes or tests. No number of interim analyses, stopping rules, or hypothesis-testing hierarchy is reported in the registry record. Without those details, the handling of multiple statistical questions cannot be assessed.

The primary analysis population is described as all subjects with at least 50 exposure days and/or with inhibitors. The record states that 148 subjects had 50 exposure days. The safety analysis set includes all 150 subjects who received at least one dose. These definitions should remain distinct when interpreting outcome results. The registry does not provide a subject-level flow or numerical endpoint denominator.

Missing-data methods are not reported in the registry record. In particular, the entry does not describe how missing inhibitor assessments, incomplete exposure information, withdrawals, or loss to follow-up were handled. It also does not report an imputation method or sensitivity analysis. The average of 188 days per subject is given in the adverse-events timeframe description, but does not specify how missing observations were managed.

The registry record does not report a detailed statistical analysis plan, adjusted analyses, or an interim-analysis plan. These omissions do not establish that such methods were absent from other trial documents; they mean that their use cannot be evaluated from the registry entry. The primary endpoint's numerical result and uncertainty are also not reported, limiting assessment of its statistical precision.

11. 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: melaena (1.3%), sinus tachycardia (0.7%), upper gastrointestinal haemorrhage (0.7%), fall (0.7%), road traffic accident (0.7%).

For all subjects treated with turoctocog alfa, the serious-adverse-event field lists 7 affected subjects among 150 at risk. The other-adverse-event field lists 36 affected subjects among 150 at risk. These are registry counts for separate event categories, not a comparison between treatment groups. The record does not report a death count.

The serious adverse event terms listed with percentages are Melaena (1.3%), sinus tachycardia (0.7%), upper gastrointestinal haemorrhage (0.7%), fall (0.7%), road traffic accident (0.7%), and hepatic enzyme increased (0.7%). They are term-specific entries and should not be added together or interpreted as mutually exclusive participants. The record does not state that each term occurred in a different subject.

General explanation: a serious adverse event is a classification of an event's seriousness, whereas an adverse event is a broader category. Counts and percentages describe what was recorded; by themselves they do not establish causation. The registry does not provide a control group, comparative risk estimates, or uncertainty intervals for these safety observations.

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

The record documents a completed phase 3, open-label, non-controlled study of turoctocog alfa in subjects with haemophilia A. Its main trial concerned prevention and treatment of bleeds, and its sub-trial concerned bleeding during surgical procedures. The primary endpoint was designed to assess FVIII inhibitor incidence using a defined exposure-based population, and the record gives a secondary outcome of adverse-event frequency.

What the posted information does not establish is the numerical result for the primary endpoint. The registry record does not report the number of inhibitor cases, the resulting estimate, or its confidence interval. It also does not report a separate numerical efficacy result for bleed prevention, bleed treatment, or surgical procedures. The design description and endpoint definition are not substitutes for those results.

The adverse-event entries show recorded events in the treated group, including the serious-event count and listed serious-event terms. They do not establish that turoctocog alfa caused those events, nor do they show how event occurrence compares with another treatment or control condition. Because there was no control group and no random allocation, the study does not provide a randomized estimate of treatment effect.

General explanation: a single-group study can be useful for describing outcomes observed during treatment and for identifying events that warrant attention, but causal interpretation is more limited than in a controlled comparison. The clinical meaning of any event also depends on context, including baseline risk and how outcomes were assessed; those details are not reported in the registry record.

Accordingly, the registry supports a description of the study design, endpoint definitions, and listed safety observations. It does not support a conclusion about the size or precision of the primary inhibitor result, a comparative treatment benefit, or whether an observed event was attributable to treatment.

13. Why This Trial Matters Statistically

This trial illustrates why a registry entry's design and analysis population matter as much as its endpoint label. The primary measure is described as an incidence rate, but its stated unit is a count of people with inhibitors relative to a population defined by exposure days and inhibitor status. Understanding that denominator rule is essential before interpreting any numerical estimate.

It also distinguishes the safety population from the primary endpoint population. The safety set includes all 150 subjects who received at least one dose, while the primary analysis includes subjects with at least 50 exposure days and/or with inhibitors. The record states that 148 subjects had 50 exposure days. Treating these populations as interchangeable could misrepresent which participants contribute to the endpoint.

The non-randomized, non-controlled, open-label design sets limits on what the observations can establish. A single treated group can provide descriptive safety information, but without a concurrent comparator it cannot estimate a treatment contrast. This distinction remains important even when a study is phase 3 or the outcome is clinically relevant.

Finally, the registry's endpoint definition is more complete than its numerical result reporting: the primary result and its precision are not reported. This is a practical reminder that a precise outcome definition does not itself convey the observed outcome. For statistical interpretation, readers need both the rule used to define the measure and the estimate with an account of its uncertainty.

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 principal limitation for interpreting the primary endpoint is that its numerical result is not reported in the registry record. The number of subjects with inhibitors, the resulting estimate, and any confidence interval are unavailable. This prevents assessment of the endpoint's magnitude and precision.

The study has no randomized control group and is described as single-group and non-controlled. Observed outcomes therefore cannot be compared with a concurrent control condition, and the design does not isolate the effect of turoctocog alfa from other influences. Its open-label status may also matter for outcomes involving assessment or reporting; details of blinded assessment are not reported in the registry record.

The primary endpoint population is defined using exposure days and inhibitor status, while the safety set is defined by receipt of at least one dose. Although the record gives the number with 50 exposure days, it does not provide the final endpoint denominator or a subject-level flow. The endpoint timeframe and exposure accounting are not described in further detail.

The registry does not report missing-data methods, sensitivity analyses, a detailed statistical analysis plan, multiplicity handling, or interim-analysis details. It also does not provide a separate numerical efficacy result for the broader aims of preventing and treating bleeds or for the surgical-procedure sub-trial. These are limitations of what can be assessed from the registry record; they do not establish what may have appeared in other trial documents.

Safety figures are descriptive and lack a control comparison or reported uncertainty intervals. The record does not provide enough information to determine whether listed events were attributable to treatment or how their occurrence compares with background risk.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of Turoctocog Alfa in Haemophilia A Subjects — NCT00840086.
• Registry record last updated 2017-03-17; status last verified 2017-02.
• Results first posted 2014-09-04.
• 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.

18. Record Summary

This is a completed phase 3, non-randomized, open-label, non-controlled, single-group trial of turoctocog alfa in subjects with haemophilia A. It includes a main trial on prevention and treatment of bleeds and a sub-trial concerning bleeding during surgical procedures. The registry lists enrollment of 150 and describes a safety analysis set of 150 treated subjects.

The primary endpoint is FVIII inhibitor incidence at a threshold of at least 0.6 Bethesda Units (BU). The primary analysis included subjects with at least 50 exposure days and/or with inhibitors; 148 subjects had 50 exposure days. The numerical primary endpoint result and its precision are not reported in the registry record.

The registry lists frequency of adverse events as a secondary outcome. For the treated group, it records 7 subjects affected by serious adverse events and 36 affected by other adverse events, among 150 at risk. These are descriptive observations without a control-group comparison.