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 Post Marketing Surveillance To Observe Safety And Efficacy Of Xyntha® In Subjects With Hemophilia A (NCT01790828), a registered phase not stated study. The primary outcome is Percentage of Participants by Family History of Factor VIII Inhibitor.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01790828 |
| Phase | Phase not stated |
| Condition | Hemophilia A |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 42 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
All enrolled participants with hemophilia A. The primary outcome description specifies all enrolled participants as its population.
Intervention
Xyntha, administered in the usual-care setting according to physician discretion.
Comparator
No like-for-like control group is described. The record does not state an allocation method, and this is not presented as a randomized comparison.
Primary question
What percentage of participants had each reported category of family history of factor VIII inhibitor?
The study is framed as post-marketing surveillance to describe the safety and efficacy of Xyntha during usual care. Its primary outcome is narrower than a direct comparison of treatment effects: it classifies participants by family history of factor VIII inhibitor. The registry record does not give the categories or the corresponding primary outcome counts or percentages.
Other registered outcomes concern use of Xyntha to treat new bleeds on demand. They include the number of infusions used for each new bleed, response type, less-than-expected therapeutic effect, and average infusion dose per bleeding. Some are specified for all participants and separately for age groups. These outcomes describe treatment use and recorded responses in the clinical setting; without a control group or reported outcome results, they do not establish comparative effects.
The stated enrollment is 42. The record does not describe a separate comparator or a prespecified contrast between treatment strategies. Consequently, the central question is descriptive: what participant characteristics and treatment experiences were recorded during Xyntha use, and what safety events were reported?
3. Trial Design
This is a completed post-marketing surveillance study of Xyntha in subjects with hemophilia A. The registry record lists Pfizer as the sponsor and an enrollment of 42 participants. The recorded study start is 2014-02, and primary completion is recorded as 2014-08. The status is COMPLETED.
The intervention is Xyntha, described in the record as recombinant coagulation factor. The arm description says it would be administered according to physician discretion. The brief summary places treatment in the usual-care setting. These details describe an observational setting in which treatment decisions were made by the physician, rather than a stated fixed treatment protocol.
The record does not state an allocation method. It does not describe a randomized comparison, and the noted comparison limitation is that the arms are not a like-for-like control comparison. The available description therefore does not support treating the study as a controlled trial for estimating a relative treatment effect. The record does not report a separate untreated or active comparator.
The primary outcome is the percentage of participants by family history of factor VIII inhibitor, with a stated timeframe of 4 years and a population of all enrolled participants. The listed secondary outcomes mainly describe on-demand treatment of bleeds, including infusion use, response type, therapeutic effect, and dose. The registry record lists 20 outcome measures and 0 analyses. It does not report the primary outcome results or numerical results for the listed secondary outcomes.
The dates and the primary outcome timeframe are both recorded as stated; the registry record does not explain how the 4-year timeframe relates to the listed study dates. Further details about follow-up, protocol procedures, and the timing of outcome assessments 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
| Stage | Xyntha |
|---|---|
| STARTED | 42 |
| COMPLETED | 8 |
| NOT COMPLETED | 34 |
Reasons for not completing this period:
| Reason | Xyntha |
|---|---|
| Other | 34 |
Analysis population for the primary outcome, as defined in the registry: All enrolled participants.
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: All enrolled participants
| Characteristic | Unit | Xyntha |
|---|---|---|
| Participants analysed | 42 | |
| Age, Continuous | years | 36.4 (SD 14.50) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 40 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants by Family History of Factor VIII Inhibitor, measured over 4 years.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is titled Percentage of Participants by Family History of Factor VIII Inhibitor. It is a participant-level description: participants are classified according to their family-history category, and the outcome is expressed as a percentage of participants. The population is listed as all enrolled participants. The registry record gives a timeframe of 4 years.
This type of measure can describe the distribution of a characteristic in the study population. Family history may be relevant context when describing a hemophilia cohort and its history of factor VIII inhibitor, but this endpoint is not itself a direct measure of how Xyntha changes bleeding, inhibitor development, or another clinical outcome. The record does not specify the family-history categories, the definition used to assign them, or how missing or uncertain family-history information would be handled.
The endpoint title identifies the planned measure, but the posted primary outcome value is not reported in the registry record. No category counts, percentages, or uncertainty estimates are listed. Without those results and the category definitions, readers cannot assess the observed distribution or its precision. The stated timeframe is also not explained in relation to the study dates in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies a descriptive post-marketing surveillance study rather than a randomized comparison. Xyntha was used in the usual-care setting, with administration according to physician discretion. This is important for interpretation: treatment choices and clinical circumstances were not described as controlled by a randomized allocation, and there is no like-for-like control group in the record.
The primary outcome concerns the percentage of participants by family history of factor VIII inhibitor. Although the outcome is named and its population and timeframe are stated, no primary result is reported in the registry record. The record therefore does not support a numerical description of the family-history distribution or an assessment of how precisely it was estimated. It also does not report a primary-outcome analysis.
The registry record lists secondary measures about on-demand treatment of bleeds, including infusion counts, response types, less-than-expected therapeutic effect, and average infusion dose. These are relevant descriptions of clinical practice and recorded treatment experience. Their numerical results are not reported in the registry record, so the listed outcome titles alone cannot show how often particular responses occurred or how much treatment was used.
Safety information lists 42 participants at risk for serious adverse events and 0 affected. For other adverse events, 42 participants were at risk and 10 were affected. These are participant counts as recorded, not comparisons between treatment groups. The record does not provide serious adverse-event terms, and deaths are not reported in the registry record. The absence of reported serious-event terms should not be taken to mean that every clinical detail about event ascertainment is available.
The record lists 20 outcome measures and 0 analyses. That distinction matters: an outcome can be registered without a corresponding numerical analysis appearing in the registry record. The record does not report effect estimates, confidence intervals, hypothesis tests, or adjustments for participant characteristics. Accordingly, there is no basis in the registry record for quantifying treatment effects or drawing comparative conclusions.
In general, descriptive observations from usual care can help characterize the population and the treatment experience captured in a surveillance record. They are also subject to the way participants were selected, how events and responses were defined, and how completely outcomes were recorded. Those details are not reported in the registry record. The stated enrollment and adverse-event counts describe the record, but do not resolve those uncertainties.
9. Statistical Methods Explained
The registry record gives an outcome title and a measure type but does not report a statistical analysis plan. The methods below explain general statistical concepts relevant to interpreting the listed outcomes; they are not claims about procedures used in this study. Specific methods, definitions, or adjustment strategies that are not described are not reported in the registry record.
What does a percentage describe?
In general, a percentage expresses the number of participants meeting a stated category or condition relative to a defined participant group. To interpret one, readers need a clear numerator, denominator, and category definition. For the primary outcome, the title indicates percentages by family history of factor VIII inhibitor and names all enrolled participants as the population. The family-history categories, category counts, percentages, and handling of missing information are not reported in the registry record. No percentage can therefore be interpreted from the outcome title alone.
A participant-level percentage is distinct from a count of events. One participant may experience multiple events, whereas a participant count records whether people were affected according to a defined rule. The safety figures are presented as numbers of participants affected and at risk. The registry record does not provide event-level totals for those safety categories.
What does a confidence interval add?
General explanation: a confidence interval describes the statistical uncertainty around an estimated quantity under a specified method and its assumptions. A narrow interval indicates greater precision than a wide interval, but neither width nor location alone resolves potential bias, incomplete outcome recording, or limitations of the study design. The registry record does not report confidence intervals for the primary outcome or the listed secondary outcomes.
For a descriptive percentage, uncertainty depends on the observed count and the number of participants with usable outcome information, as well as the interval method. The registry record does not report the family-history counts or the number with usable information. It therefore does not permit a precision assessment for the primary endpoint. The same limitation applies to the listed secondary outcomes because their numerical results are not reported in the registry record.
Why does the comparison structure matter?
General explanation: randomized allocation can make groups more comparable, on average, for characteristics that affect outcomes. An observational or usual-care comparison does not have that protection. When treatment is administered according to physician discretion, treatment decisions may be related to clinical circumstances. If treatment groups differ, an observed outcome contrast could reflect those differences as well as treatment. In this record, no like-for-like control comparison is described, so comparative causal interpretation is not supported.
The record does not state an allocation method, a comparator protocol, or an adjusted model. It also does not report estimates that could be reviewed for confounding or precision. The absence of these details means readers should interpret the study as surveillance and description rather than as a controlled estimate of a treatment effect.
How should repeated bleed outcomes be understood?
General explanation: outcomes measured across multiple bleeds can be analyzed at the event level or summarized at the participant level. Repeated observations from the same participant are often related, so treating each bleed as fully independent can understate uncertainty. Appropriate analysis depends on the exact outcome definition, the data structure, and the intended estimand. The registered secondary outcomes refer to infusions and responses for new bleeds, but the registry record does not report the analysis unit, statistical model, or treatment of repeated observations.
Over-dispersion is a general concern when count outcomes vary more than a simple count model expects. If present, it can make conventional model-based uncertainty estimates too small. Whether it is relevant depends on the distribution and analysis of the observed count data. Those data and methods are not reported in the registry record, so no conclusion about over-dispersion can be made for this study.
What does the planning illustration represent?
General explanation: a sample-size planning illustration asks how many participants might be needed under specified assumptions to detect an effect of a chosen size at a chosen significance level and power. It is a design calculation, not an observed result, and it does not show that a study had a particular probability of detecting its actual effect. The planning assumptions associated with this record specify a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Time-to-event calculations use a total event count, while other calculations are expressed as participants per arm for 80% power or another stated power level.
These are planning assumptions, not evidence that this study used a two-arm randomized design. The record describes no like-for-like control comparison, and it does not report the study's own sample-size justification. The actual planning illustration values are not reported in the registry record. Any such illustration should be read only as a hypothetical planning exercise, never as observed power or as proof that the study was adequately sized.
Finally, the registry lists 20 outcome measures and 0 analyses. It does not report the statistical methods used for each outcome, the handling of missing data, or adjustments for multiple outcomes. Those omissions limit the ability to reproduce or fully evaluate any analysis from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 20 outcome measures, including a primary endpoint and multiple secondary outcomes, but lists 0 analyses. It does not report a multiplicity strategy, such as a hierarchy of hypotheses or an adjustment to account for testing several outcomes. General statistical context: when many hypotheses are tested, the chance of at least one apparently notable result can increase if each is interpreted in isolation. Whether that concern applies to a particular result depends on the analyses actually performed, which are not reported in the registry record.
The record does not report how missing outcome information was handled, how many participants had complete data for each outcome, or whether any participants were excluded from particular analyses. The primary outcome names all enrolled participants as its population, but the number with recorded family-history information is not reported in the registry record. For the secondary outcomes, the outcome descriptions alone do not establish the analysis population or the completeness of the observations.
Analysis populations are also not defined in the registry record. It does not state whether analyses used all enrolled participants, participants who received treatment, or another defined group. These details matter because estimates can depend on who contributes data and how missingness is addressed. Without the analysis population, outcome availability, and multiplicity approach, readers cannot assess the robustness of any outcome analysis. No such analysis results are reported in the registry record.
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 |
|---|---|---|---|
| Xyntha | 0 | 42 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Xyntha | 10 of 42 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Xyntha |
|---|---|---|
| Gastritis | Gastrointestinal disorders | 3 of 42 |
| Haemarthrosis | Musculoskeletal and connective tissue disorders | 2 of 42 |
| Myalgia | Musculoskeletal and connective tissue disorders | 2 of 42 |
| Headache | Nervous system disorders | 1 of 42 |
| Dyspepsia | Gastrointestinal disorders | 1 of 42 |
| Irritable bowel syndrome | Gastrointestinal disorders | 1 of 42 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 1 of 42 |
| Ligament disorder | Musculoskeletal and connective tissue disorders | 1 of 42 |
| Muscle haemorrhage | Musculoskeletal and connective tissue disorders | 1 of 42 |
| Intervertebral disc disorder | Musculoskeletal and connective tissue disorders | 1 of 42 |
The serious adverse-event figures list 42 participants at risk and 0 participants affected. The figures for other adverse events list 42 at risk and 10 affected. These are participant counts, not event rates calculated for a particular follow-up duration, and no between-group comparison is presented. The registry record does not report serious adverse-event terms. Deaths are not reported in the registry record.
General explanation: a count of participants affected is not the same as a count of individual events. A participant may experience more than one event, and the count does not convey event severity, duration, relatedness, or timing. The registry record does not provide those details for the figures stated.
The serious-event count of 0 is a recorded observation in this group; it does not establish that the risk of serious events is absent. The number of participants and the completeness and duration of event surveillance affect how much can be inferred from a zero count. Follow-up details and event-ascertainment methods are not reported in the registry record. The safety figures should therefore be read as descriptive counts, not as evidence from a controlled safety comparison.
12. What the Result Does, and Does Not, Mean
The record documents a completed post-marketing surveillance study of Xyntha in people with hemophilia A, with enrollment of 42 and administration according to physician discretion in a usual-care setting. It identifies a primary outcome concerning family history of factor VIII inhibitor and lists secondary outcomes related to on-demand treatment of bleeds. It also records participant counts for serious and other adverse events.
Those details describe the study's scope, but the record does not report numerical primary or secondary outcome results. It therefore does not show the distribution of family-history categories, the number of infusions per bleed, the response categories observed, or the average infusion dose. It also does not report a comparative estimate of efficacy or safety. Outcome titles should not be mistaken for findings.
The safety record states that 0 of 42 participants were affected by serious adverse events and 10 of 42 were affected by other adverse events. These counts are descriptive. They do not show what would have occurred under another treatment or without treatment, and the record does not provide event terms or deaths. The absence of a reported serious event in the listed count is not proof that serious events cannot occur.
General statistical interpretation: an uncontrolled usual-care study can provide descriptive information about treatment use and recorded events, but it cannot by itself separate treatment effects from differences in patient circumstances or other influences. This record does not describe a like-for-like comparator, and the statistical analysis details are not reported in the registry record.
The findings that can be stated are therefore limited to the design, registered outcome topics, enrollment, and posted safety counts. The registry record does not establish that Xyntha caused a particular outcome, nor does it establish a comparative benefit or harm. It also does not provide enough outcome detail to assess the precision of the primary endpoint.
13. Why This Trial Matters Statistically
Post-marketing surveillance addresses treatment use in ordinary clinical care, where choices may be made according to physician discretion rather than a uniform trial assignment. Such records can be useful for describing which outcomes researchers set out to track and what safety counts are recorded. This study's stated purpose is to describe the safety and efficacy of Xyntha in the usual-care setting.
Statistically, the distinction between description and comparison is central. The record does not describe a like-for-like control group or a randomized comparison. As a result, the outcomes are not framed as estimates of a relative treatment effect. The study can be read as a surveillance record, but the design details do not support interpreting it as a controlled efficacy comparison.
The registered outcome set also illustrates why outcome definitions and analysis plans matter. The listed measures cover participant characteristics, infusion use, response types, therapeutic effect, and dose. These outcomes are not interchangeable: some are participant-level descriptions, while others concern repeated treatment events. Clear definitions, analysis populations, and methods for correlated observations would be needed to evaluate the resulting estimates. Those details are not reported in the registry record.
The registry lists 20 outcome measures and 0 analyses, while the numerical results for the primary and secondary outcomes are not reported in the registry record. That gap limits statistical interpretation even when outcome topics are clearly identified. Readers need results and measures of uncertainty to judge what the observations show and how precisely they do so.
The record's value is therefore in documenting a surveillance study and its intended areas of observation, alongside the posted safety counts. Its limitations are equally important: without reported outcome analyses and a comparable control group, it cannot answer a causal or comparative question.
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 primary limitation for interpreting this study is that the registry record does not report numerical primary outcome results. The endpoint title gives no category counts or percentages for family history of factor VIII inhibitor, and the family-history categories themselves are not described. The record also does not report numerical results for the listed secondary outcomes.
The comparison structure is limited for causal interpretation. Treatment was administered according to physician discretion in usual care, the allocation method is not stated, and no like-for-like control comparison is described. Clinical decisions and participant circumstances may therefore differ in ways that cannot be evaluated from the record. No adjustment strategy or model is reported.
Other important details are not reported in the registry record: the statistical analysis plan, analysis populations, outcome-specific denominators, missing-data handling, and multiplicity strategy. The record lists 20 outcome measures and 0 analyses. It does not explain how repeated bleed-level observations were analyzed or whether within-participant dependence was accounted for.
The safety information is limited to participant counts: 0 of 42 affected by serious adverse events and 10 of 42 affected by other adverse events. Serious adverse-event terms are not listed, and deaths are not reported in the registry record. Event definitions, relatedness, timing, ascertainment, and follow-up details are also not reported.
Finally, the registry record states a 4-year timeframe for the primary outcome while listing study dates from 2014-02 to 2014-08. It does not explain how that timeframe relates to the recorded dates. The record also does not report the study's sample-size justification. These missing details restrict evaluation of follow-up, precision, and the intended analysis.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Post Marketing Surveillance To Observe Safety And Efficacy Of Xyntha® In Subjects With Hemophilia A — NCT01790828.
- Registry record last updated 2015-08-17; status last verified 2015-07.
- Results first posted 2015-08-17.
- 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
This completed post-marketing surveillance study concerns Xyntha use in people with hemophilia A. The registry record lists Pfizer as sponsor, an enrollment of 42, a start date of 2014-02, and primary completion in 2014-08. Treatment was described as usual care, administered according to physician discretion.
The primary outcome is the percentage of participants by family history of factor VIII inhibitor, with a stated timeframe of 4 years. Secondary outcomes concern on-demand treatment of bleeds, including infusion use, response type, less-than-expected therapeutic effect, and dose. The registry record lists 20 outcome measures and 0 analyses; numerical primary and secondary outcome results are not reported in the registry record.
Safety figures list 0 of 42 participants affected by serious adverse events and 10 of 42 affected by other adverse events. Serious-event terms and deaths are not reported in the registry record. No like-for-like control comparison is described, so the record supports descriptive interpretation rather than a comparative treatment-effect estimate.