PF-05208756, Moroctocog Alfa (AF-CC), Xyntha For Hemophilia A: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PF-05208756, Moroctocog Alfa (AF-CC), Xyntha For Hemophilia A (NCT02492984), a na phase 4 study. The primary outcome is Percentage of Participants With Factor VIII (FVIII) Inhibitors.

2. Clinical Question

3. Trial Design

This was a completed Phase 4, open-label, single-arm, post-authorization pragmatic clinical trial of Xyntha in usual-care settings in China. The registry lists 85 enrolled participants. It gives a start date of 2015-04 and a primary completion date of 2016-07.

Participants received intravenous Xyntha. The described treatment settings were on-demand treatment and surgical prophylaxis. For these settings, the treating physician prescribed dose and frequency in accordance with the Xyntha label; the registry description says these could be adjusted according to medical and therapeutic needs. The planned treatment period was approximately 6 months or approximately 50 exposure days, whichever came first. The primary endpoint's follow-up period extended through 28 calendar days after the end of treatment.

The study did not allocate participants randomly to treatment groups and did not include a like-for-like control arm. On-demand treatment and surgical prophylaxis are reported as groups, but they are not randomized comparison groups. Their participant characteristics, clinical circumstances, and reasons for receiving each treatment may differ. Consequently, differences between the group results cannot be interpreted as causal treatment effects.

The registry lists safety and efficacy outcomes, including treatment-emergent adverse events, responses to on-demand treatment of bleeds, infusions needed for bleeds, surgical hemostatic efficacy, blood loss, transfusion requirements, and FVIII consumption. Specific protocols, detailed eligibility criteria, and the statistical plan 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.

Before assignment: As there were 2 participants who rolled over from the surgical prophylaxis group to the on-demand group should be counted once in total column, the total number of baseline participants was 85.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The safety analysis set was defined as all participants who received at least one dose of Xyntha during the study.

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.

Population: As there were 2 participants who rolled over from the surgical prophylaxis group to the on-demand group should be counted once in total column, the total number of baseline participants was 85.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Factor VIII (FVIII) Inhibitors, measured over From Day 1 up to 28 calendar days after End of Treatment (participants had received treatment for 6 months or when participants had achieved 50 exposure days [EDs] whichever occurred first)..

The primary endpoint is the percentage of participants with FVIII inhibitors. The registry describes FVIII inhibitor development during the study as a product medically important event. In general, this kind of endpoint represents the proportion of an eligible analysis group who experienced a specified event within the stated observation period. It is a safety measure, not a comparison of treatment with a control group.

The defined safety analysis set includes participants who received at least one dose of Xyntha. The endpoint's time frame begins on Day 1 and continues until 28 calendar days after treatment ends. Treatment was described as lasting 6 months or until 50 exposure days, whichever came first. The registry record does not report the primary endpoint's observed percentage, its numerator and denominator, or its stated 95% confidence interval. Those values therefore cannot be interpreted from the endpoint definition alone.

In general, monitoring inhibitor development is relevant to describing safety during treatment with a factor replacement product. However, the presence of an endpoint in the registry does not establish how often it occurred. The registry's separate listing of Factor VIII inhibition among serious adverse event terms does not substitute for a reported primary endpoint result: the record does not establish that the term's count, percentage, and analysis population correspond to the primary endpoint calculation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a percentage with a confidence interval describe?

For an event-based endpoint, a percentage describes the share of an analysis group recorded as having the event. The registry defines the primary endpoint as the percentage of participants with FVIII inhibitors and specifies a 95% confidence interval. In general, a confidence interval conveys the uncertainty associated with an estimate under the statistical method used to construct it. A narrower interval indicates greater statistical precision than a wider interval, though an interval does not remove limitations in study design or event measurement.

The registry record does not report the primary estimate, its event count, its denominator, or the confidence interval limits. It also does not report the method used to calculate that interval. As a result, readers cannot evaluate the numerical precision or reproduce the primary estimate from the endpoint definition. A stated plan to report a confidence interval is not itself an observed result.

What does a single-arm design allow readers to learn?

In a single-arm study, participants receive the study intervention without a separate control group. The resulting summaries describe the enrolled and analyzed participants during the recorded period. They can provide descriptive information about observed events, but they do not directly estimate a contrast against an alternative treatment or no treatment.

Here, allocation is listed as not applicable, masking as none, and the model as single group. The on-demand and surgical prophylaxis groups are treatment settings, not randomized arms. Because assignment to these settings was not randomized, comparisons between their counts may reflect differences in participants, circumstances, or clinical decisions as well as any treatment-related factors. The registry does not report a statistical adjustment intended to address such differences.

How should the adverse-event counts be read?

The registry reports participants at risk and participants affected for serious and other treatment-emergent adverse events. For serious events, the listed counts are 7 of 73 in the on-demand group, 1 of 14 in the surgical prophylaxis group, and 8 of 85 in the total. For other treatment-emergent events, they are 62 of 73, 9 of 14, and 70 of 85, respectively. These are reported counts, not estimates from a randomized comparison.

In general, counts need their analysis population and event definition to be interpreted. The safety analysis set is defined as all participants receiving at least one dose, but the record does not provide further detail on how missing observations, incomplete follow-up, or repeated events were handled in these summaries. The adverse-event figures count participants affected; they should not be mistaken for counts of all event episodes.

What can be inferred from the listed serious-event terms?

The registry names Factor VIII inhibition at 8.2% and gingival injury at 1.4% among the top serious adverse event terms. These are term-level summaries. The record does not supply their denominators, further event-count detail, or a clear mapping to the primary endpoint's analysis. General statistical practice distinguishes a term listed in adverse-event reporting from an independently defined endpoint, even when the terminology appears related. The term percentage therefore cannot fill in the missing primary endpoint estimate.

What do the planning illustrations mean?

The record describes sample-size illustrations based on the observed effect, with two-sided significance level 0.05, equal allocation between hypothetical arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning illustrations, not observed results and not observed power. They do not change the fact that this trial itself was single-arm. The numerical planning outputs and the observed primary effect are not reported in the registry record, so no specific sample-size requirement can be interpreted.

In general, a planning sample size depends on assumptions about the outcome, the effect a future study aims to detect, the error rate, allocation, and the analysis method. If the true effect differs from the assumed effect, the resulting planning calculation may not describe the future study's performance. A sample size calculated from an observed effect is particularly dependent on the stability and precision of that estimate. No sample-size justification for this trial is reported in the registry record.

What remains unknown about the statistical plan?

The registry record does not report the primary endpoint's calculation method, any adjustment strategy, or a detailed statistical analysis plan. It does not report interim analyses or explain whether the stated endpoint analysis was prespecified in the protocol. These omissions limit assessment of how the reported outcome definitions and summaries were selected and applied. General statistical interpretation should therefore remain descriptive and tied to the details that the registry actually records.

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("On-Demand Group", "Surgical Prophylaxis Group")
n      <- c(73, 14)
events <- c(6, 1)
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  On-Demand Group  73  6  8.2  3.1  17.0  3.8  16.8  3.9  16.8
ARM  Surgical Prophylaxis Group  14  1  7.1  0.2  33.9  1.3  31.5  1.7  31.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes. These include treatment-emergent adverse events, responses to on-demand treatment of bleeds, infusions needed for new bleeds, surgical prophylaxis outcomes, transfusion requirements, and FVIII consumption. When a study examines multiple outcomes, the chance of finding at least one apparently notable result can depend on how many analyses are performed and how they are interpreted. In general, multiplicity methods can address this issue, but the registry record does not report whether any adjustment was planned or used.

The record does not provide a detailed statistical analysis plan, identify which secondary outcomes were formally tested, or describe any hierarchy among them. It also does not report numerical results for the primary endpoint or the listed secondary outcomes in the registry record for this record. Consequently, the outcome list alone cannot establish which analyses were completed, whether they were exploratory, or how uncertainty should be assessed across them.

Missing-data handling is also not reported in the registry record. The safety analysis set is defined as participants who received at least one dose of Xyntha, but that definition does not explain how participants with incomplete follow-up or unavailable outcome information were treated in each analysis. The registry does not state whether missing endpoint values were excluded, imputed, or handled by another approach.

These gaps matter because analysis populations, missing observations, and multiplicity choices can affect the interpretation of estimated event percentages and their uncertainty. Without those details, readers should avoid assuming that every enrolled participant contributed data to every outcome or that the listed endpoint summaries account for missingness in a particular way.

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: factor viii inhibition (8.2%), gingival injury (1.4%).

The serious adverse-event counts are reported as 7 affected among 73 at risk in the on-demand group, 1 among 14 in the surgical prophylaxis group, and 8 among 85 in total. The registry separately lists other treatment-emergent adverse events as 62 among 73, 9 among 14, and 70 among 85. These categories are reported separately; the record does not explain further how events were classified or whether participants could appear in more than one event category.

The registry's top serious adverse event terms are Factor VIII inhibition at 8.2% and gingival injury at 1.4%. The denominator and calculation details for these term percentages are not reported in the registry record. The Factor VIII inhibition term should not be assumed to be the primary endpoint estimate, because the record does not show that the term summary and endpoint share the same definition or analysis population.

In general, an adverse event recorded during a trial is not by itself proof that the intervention caused it. An open-label, single-arm study can describe events occurring during treatment, but without a control group it cannot estimate how event occurrence compares with another treatment. The counts are descriptive safety information, not a causal comparison.

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

The registry record describes a completed trial of Xyntha in usual-care settings and identifies FVIII inhibitor development as the primary endpoint. However, it does not report the primary endpoint percentage or its 95% confidence interval. The central numerical result for that endpoint is therefore not available in the registry record, and the endpoint definition alone cannot establish how often inhibitors occurred.

The posted adverse-event summaries do show counts of participants affected by serious and other treatment-emergent adverse events in the on-demand and surgical prophylaxis groups and in total. The listed serious-event terms include Factor VIII inhibition and gingival injury, each with a reported percentage. These descriptions characterize events recorded in the study; the registry does not provide sufficient detail to equate the Factor VIII inhibition term summary with the primary endpoint estimate.

Because this was an open-label, single-arm trial, the results do not supply a randomized estimate of how outcomes compare with another treatment or with no treatment. The on-demand and surgical prophylaxis groups are not like-for-like control groups. Differences between their event counts cannot be attributed to treatment setting alone, since the registry does not report random assignment or a comparative adjustment.

In general, statistical estimates are interpreted alongside their uncertainty, population definition, event definition, and design. The missing primary estimate and interval prevent assessment of its reported precision. Missing details about analysis methods, missing observations, and multiplicity further limit interpretation of the listed outcomes. The results can be read as descriptive registry reporting, not as proof that treatment caused or prevented an event or as a comparative estimate of efficacy.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between describing outcomes and estimating a treatment contrast. Its open-label, single-arm design can document safety and clinical outcomes in the enrolled group under usual-care conditions. It does not provide a randomized control group from which to estimate a comparative effect. Treating the on-demand and surgical prophylaxis groups as if they were equivalent comparison arms would overlook the design and the different clinical contexts in which those treatments were used.

The primary endpoint illustrates why a registry outcome definition is not the same as a reported result. The endpoint specifies FVIII inhibitors, a safety analysis population, an observation period, and a 95% confidence interval as its dispersion measure. Yet the numerical endpoint estimate and interval are not reported in the registry record. Without them, readers cannot assess the observed frequency or its precision.

The adverse-event summaries provide descriptive counts and list serious event terms, but they do not resolve the missing primary endpoint result or establish causation. In general, sound interpretation requires attention to the denominator, analysis population, event definition, follow-up, uncertainty, and study design. The record leaves some of those details unspecified, including the primary calculation method and the handling of missing outcome information.

The trial therefore matters statistically as a reminder to distinguish a defined endpoint, an adverse-event listing, and an interpretable comparative result. Each answers a different question. The posted information supports a description of selected recorded events, while key details needed to evaluate the primary endpoint and draw comparative conclusions are not reported in the registry record.

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 primary limitation for interpreting the main safety question is that the registry record does not report the primary endpoint estimate or its 95% confidence interval. The endpoint is defined, but its numerical result cannot be evaluated. The Factor VIII inhibition term listed among serious adverse events does not resolve this gap because the record does not specify how that term-level summary relates to the endpoint calculation.

The single-arm, open-label design has no randomized control group. It can describe outcomes among participants treated in the study, but it cannot by itself separate treatment-related effects from other explanations for recorded events. The on-demand and surgical prophylaxis groups are not randomized, like-for-like controls, and their counts should not be interpreted as a causal comparison.

The registry does not report the statistical analysis plan, the method used to calculate the primary confidence interval, or how missing observations were handled. It also does not report whether multiplicity adjustments were used for the range of listed outcomes. These omissions make it difficult to assess the precision and analysis choices behind the outcome summaries.

Additional details that could affect interpretation, including the denominators and methods for the listed serious-event term percentages, are not reported in the registry record. The treatment description says dose and frequency were prescribed by the treating physician, but the record does not give further details on actual exposure or outcome-specific follow-up. The listed adverse-event counts therefore should be treated as registry descriptions rather than complete comparative evidence.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: PF-05208756, Moroctocog Alfa (AF-CC), Xyntha For Hemophilia A — NCT02492984.
• Registry record last updated 2017-04-04; status last verified 2017-02.
• Results first posted 2017-04-04.
• 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.

19. Record Summary

NCT02492984 is a completed Phase 4, open-label, single-arm, post-authorization pragmatic clinical trial of intravenous Xyntha in people with hemophilia A in usual-care settings in China. The registry lists enrollment of 85 and a planned treatment period of approximately 6 months or approximately 50 exposure days, whichever came first.

The primary endpoint was the percentage of participants with FVIII inhibitors, with a 95% confidence interval specified. Its observed percentage and interval are not reported in the registry record. The record lists serious adverse events affecting 7 of 73 participants in the on-demand group, 1 of 14 in the surgical prophylaxis group, and 8 of 85 in total. The study has no randomized control group, so its findings are descriptive rather than comparative.