HemLibra Prophylaxis in Patients With Hemophilic Pseudotumor: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for HemLibra Prophylaxis in Patients With Hemophilic Pseudotumor (NCT03921294), a na phase 4 study. The primary outcome is Hemostatic Efficacy of Prophylactic Weekly Injections of Hemlibra (Emicizumab) Based on Hemoglobin.

2. Clinical Question

This question is narrower than a comparison of treatments: the study record describes following hemoglobin over time in treated participants, not estimating a contrast between emicizumab and another intervention. The planned assessment interval was every 6 months over the stated 2 years and 10 months of the patient's study participation duration. The record also lists secondary outcomes concerning breakthrough bleeds, pseudotumor status, quality of life, adverse events, and anti-drug antibodies.

The registry does not report the results for these questions. In particular, it does not provide baseline and follow-up hemoglobin values, a change estimate, or a summary of the listed secondary outcomes. The clinical question can therefore be identified from the study description, but its answer cannot be determined from the posted results in this record.

3. Trial Design

This was a prospective, open-label, single-group phase 4 study sponsored by Indiana Hemophilia &Thrombosis Center, Inc. The registry describes it as a United States, single-center study of emicizumab for hemostatic control in hemophilia A patients with hemophilic pseudotumor. The allocation field is not applicable, and masking is listed as none. There is no randomized or concurrent control group in the record.

The intervention is emicizumab, with the arm description stating that patients with hemophilic pseudotumor would receive prophylactic treatment and be assessed for improvement. The primary outcome title specifies weekly injections. The listed enrollment is 1, and the study status is terminated. The record gives a study start date of 2019-05-15 and a primary completion date of 2022-03-16. It does not report why the study was terminated.

The primary outcome is hemoglobin, expressed in gm/dL, summarized as a mean with full range. Its timeframe is described as measurement every 6 months during the patient's study participation duration of 2 years and 10 months. The stated purpose is to assess maintenance or increase from baseline using serial blood tests. The record also lists secondary outcomes for breakthrough bleeds, pseudotumor status, patient quality of life measured with Haem-A-QOL and EQ-5D-5L, adverse events, serious adverse events, and anti-drug antibodies.

The registry lists 15 outcome measures and 0 analyses. It does not report the analysis population, missing-data procedures, or a statistical analysis plan. Nor does it provide values for the primary outcome. These omissions limit interpretation: the design and intended measurements are described, but the record does not establish how the planned assessments were analyzed or what the observed clinical measurements were.

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

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: Patients with Factor VIII deficiency and hemophilia pseudotumor.

6. Primary Endpoint

The registry lists the primary outcome as Hemostatic Efficacy of Prophylactic Weekly Injections of Hemlibra (Emicizumab) Based on Hemoglobin, measured over Every 6 months, for the 2 years and 10 months of the patient's study participation duration..

The primary endpoint is hemoglobin, measured in gm/dL through serial blood tests. The registry describes the intended outcome as maintenance or increase from each participant's baseline level. It lists the measure as a mean with full range and gives an assessment timeframe of every 6 months over the patient's study participation duration of 2 years and 10 months.

The registry identifies this endpoint as its measure of hemostatic efficacy. In general, repeated measurements can describe how a laboratory measure changes over a period of observation; a baseline reference makes the direction of change meaningful. Here, however, the record does not report the baseline value, later values, the number of measurements, or a calculated change. It therefore does not show whether hemoglobin was maintained or increased in the observed study data.

A mean summarizes the central level of a set of observations, while a full range describes its lowest and highest values. These summaries can be informative about observed measurements, but they do not by themselves show how precise an estimated change is. No confidence interval, variability estimate beyond the specified full range, or inferential result for the primary outcome is reported in the registry record. The record also does not explain why hemoglobin was selected over the other listed outcomes or specify a clinically meaningful threshold for change. The outcome's stated role is clear; the evidence needed to interpret its observed magnitude is not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes an observational structure for the outcome measurements within a prospective intervention study: emicizumab was to be given and hemoglobin assessed over time. It identifies no random allocation and no separate control arm. Accordingly, the design does not produce a randomized between-group contrast. General statistical interpretation of a single-group study focuses on the observed course in that group, while recognizing that an observed change does not isolate the effect of treatment from other influences.

What does the endpoint summary mean?

The primary measure is specified as a mean with full range. In general, a mean combines observed values into a central summary, while a full range reports the smallest and largest observations. The mean can make a set of measurements easier to describe, but may not reveal whether values are clustered or whether an extreme observation affects the summary. The range gives information about spread at the endpoints, but does not show the pattern of values between them. Neither summary is a substitute for the underlying observations or for an estimate of uncertainty.

The registry's endpoint description calls for serial measurements and comparison with baseline. In general, repeated observations can be examined as a trajectory or as a change from a reference measurement. The record does not specify how measurements at different visits would be combined, how change would be estimated, or how incomplete follow-up would be handled. It does not post the actual measurements. Thus, the listed mean and full range describe the intended form of the outcome, not a reported result.

Would a confidence interval clarify precision?

In general, a confidence interval expresses the statistical uncertainty around an estimate under a specified method and its assumptions. It helps distinguish a relatively precise estimate from one compatible with a wider range of values. No confidence interval for hemoglobin or any other efficacy outcome is reported in the registry record. There is therefore no posted interval to interpret, and no basis for inferring the precision of an unreported effect estimate. A confidence interval would not by itself address the absence of a comparator or other design limitations.

What does the sample-size planning information represent?

The planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. The record also distinguishes the reporting convention for time-to-event outcomes from other outcomes. These are planning assumptions, not evidence that this single-group study used a two-arm design. The sample-size illustration is not an observed-power calculation and does not show what the study could detect in practice.

The registry record does not report a sample-size justification for the actual study design, and it does not report the observed effect needed to evaluate the planning illustration's reference point. No sample-size values for those illustrations are stated in the record. Any planning figures should be read as hypothetical design illustrations rather than as observed results, a statement of achieved power, or evidence about the efficacy endpoint.

What is the role of the listed analysis count?

The record lists 0 analyses. That is a registry reporting fact; it does not describe a test statistic, model, estimate, or adjustment. No statistical model, hypothesis test, confidence interval method, or sensitivity analysis is reported. It is therefore not possible to evaluate the assumptions of an analysis or check whether an analysis matches the stated endpoint.

Over-dispersion is a general concern when data vary more than a statistical model assumes. In general, ignoring excess variation can make uncertainty appear smaller than it is. The registry does not report a model or distributional assumptions for the outcomes, and no relevant analysis is available to assess. This is not a claim that over-dispersion occurred in this study; it explains why model details would matter if count or other variable outcomes were analyzed.

For this record, the clearest method-level conclusion is that the study design and intended endpoint are described, while the analytical procedures and efficacy results are not. Statistical concepts such as means, ranges, confidence intervals, and model assumptions can explain how results might be interpreted, but cannot recover results that the registry does not report.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, including the primary hemoglobin measure and secondary outcomes for bleeding, pseudotumor status, quality of life, adverse events, and anti-drug antibodies. When a study evaluates multiple outcomes, there can be more than one opportunity to find an apparently notable result by chance. In general, a prespecified multiplicity strategy can help clarify how evidence across several outcomes is interpreted. No multiplicity procedure or hierarchy for the outcomes is reported in the registry record.

The record lists 0 analyses and does not provide statistical results for the primary or secondary outcomes. It does not report which outcomes were analyzed, whether any were prioritized after data collection, or how interpretation across outcomes was handled. These details cannot be inferred from the outcome list alone.

Missing-data methods are also not reported in the registry record. The study description indicates serial hemoglobin measurements, but the record does not state whether all planned measurements were obtained, how missing visits or measurements were treated, or whether any imputation or sensitivity analysis was used. No analysis population is reported, so the record does not say which observations would be included in an efficacy analysis or how that population relates to enrollment.

These are reporting gaps rather than evidence that a particular approach was or was not used outside the registry record. With no posted efficacy values, analysis description, or missing-data account, the robustness of any outcome estimate cannot be assessed. The listed enrollment and outcome schedule alone do not establish completeness of follow-up or analytic inclusion.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry's safety summary lists 1 participant at risk for serious adverse events and 0 affected. It also lists 1 participant at risk for other adverse events and 1 affected. The death count is 0. These are the safety figures recorded for the single arm. The record lists no top serious adverse-event terms.

These counts should be read as registry summaries, not as a detailed account of events. The record does not name the other adverse event, describe its severity or timing, or state whether it was considered related to emicizumab. The absence of a listed serious-event term does not add detail about the nature of the observation recorded in the other adverse-event category. The safety summary also does not provide a narrative describing how events were collected or classified.

With enrollment listed as 1, these counts describe a very limited amount of safety information. They do not estimate how often adverse events might occur in a broader population, and they do not establish comparative safety because there is no control group. The registry's counts should not be interpreted as evidence of safety or harm beyond what those recorded figures state. Follow-up duration for the safety observations is not reported in the registry record, so the time at risk cannot be assessed from these counts alone.

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

The record means that a prospective, open-label, single-group phase 4 study was registered to assess prophylactic emicizumab in patients with hemophilic pseudotumor. The planned primary measure was maintenance or increase of hemoglobin from baseline, assessed by serial blood tests. The record also names several secondary clinical, quality-of-life, and safety outcomes. These details establish the study's stated purpose and measurement plan.

It does not establish the observed effect on hemoglobin. No baseline or follow-up values, mean, range, or statistical estimate of change are reported. There are no reported analyses to provide a test result or an interval describing uncertainty. A reader therefore cannot determine from this record whether hemoglobin changed, how much it changed, or how consistent any pattern was across observations.

The design would not support a direct treatment-versus-control comparison even if a within-group change were available. In general, change over time in a single group may be influenced by factors other than the intervention. The record lists enrollment of 1, so it also offers little basis for characterizing outcomes across the intended patient population. These are limits on what this design and record can establish, not statements about an unreported clinical outcome.

The status is terminated, but the reason is not reported in the registry record. The record does not explain whether the study ended as planned, whether all intended measurements were collected, or how the termination affected the availability of results. The safety summary records 0 serious adverse events affected, 1 participant affected by other adverse events, and 0 deaths; it gives no further description of the other adverse event.

Overall, the registry supports a description of the intended study and a limited safety count, but not an efficacy conclusion. It neither demonstrates benefit nor demonstrates lack of benefit. The primary result and its uncertainty are not reported, and no comparative estimate is available.

13. Why This Trial Matters Statistically

This study is statistically notable because its clinical question is framed around an intervention, but its design is a single group without a concurrent comparator. That distinction matters. A before-and-after pattern could describe what happened during observation, but a treatment effect is a comparative concept: it asks how outcomes differ relative to what would have happened under another condition. A single-group record cannot directly supply that contrast.

The enrollment listed is 1. This makes the limits of descriptive evidence especially important. A measurement trajectory, even if reported, would describe the enrolled participant's observations rather than estimate the range of outcomes among the broader population in the eligibility description. The registry does not report the primary measurements, so even that individual-level trajectory cannot be assessed.

The endpoint illustrates a second statistical issue: defining a measure and schedule does not amount to reporting an estimate. The record specifies hemoglobin, a mean and full range, serial blood tests, and a baseline reference. Interpretation still requires observed values, an analysis method, and some indication of precision. Without those, the stated endpoint remains a plan rather than an interpretable efficacy result.

Finally, the listed 15 outcomes raise the general issue of interpreting multiple measures, while the registry record reports no analyses or multiplicity strategy. The safety counts offer a narrow descriptive snapshot but do not create a comparative safety estimate. The statistical importance of the record lies in separating what its design and registrations establish from what the absent results cannot establish.

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 is that the registry does not report results for the primary endpoint. It provides no hemoglobin values at baseline or follow-up, no mean or full range, and no estimate of change. It also provides no statistical analysis results or precision measure. The intended efficacy question therefore remains unanswered in the posted results.

The single-group design has no concurrent comparator, and the listed enrollment is 1. Any inference would be limited to the observations available from that study rather than a controlled estimate of treatment effect. The registry does not report why the study was terminated, whether the planned observations were completed, or the actual follow-up duration. Its stated measurement timeframe does not establish how much follow-up occurred.

The record does not report an analysis population, handling of missing measurements, statistical model, or sensitivity analysis. It also does not report how the 15 listed outcome measures were prioritized or how multiplicity was addressed. These omissions limit assessment of both the reliability and the interpretation of any potential analysis.

For safety, the registry records 0 serious adverse events affected, 1 affected by other adverse events, and 0 deaths, but it does not identify the other adverse event, provide event-level detail, or state attribution. The number of observations and absence of comparative data restrict what can be inferred from these counts. The reasons for termination and any sample-size justification for the actual study are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: HemLibra Prophylaxis in Patients With Hemophilic Pseudotumor — NCT03921294.
• Registry record last updated 2024-04-11; status last verified 2024-03.
• Results first posted 2024-03-20.
• 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

NCT03921294 is a phase 4, prospective, open-label, single-group study of prophylactic emicizumab for patients with hemophilic pseudotumor. The registry describes the population as patients with hemophilia A, baseline FVIII levels <40%, and with or without inhibitors. Enrollment is listed as 1. The study is marked terminated; its listed start date is 2019-05-15 and primary completion date is 2022-03-16. The reason for termination is not reported in the registry record.

The primary outcome is hemoglobin maintenance or increase from baseline, measured in gm/dL using serial blood tests and summarized as a mean with full range. The record lists 15 outcome measures and 0 analyses, but reports no primary efficacy values or analysis results. The safety summary lists 0 serious adverse events affected, 1 participant affected by other adverse events, and 0 deaths. These entries provide limited descriptive information, not a comparative estimate of efficacy or safety.