Post-Authorization Safety, Tolerability and Immunogenicity Evaluation of HyQvia in Pediatric PIDD Subjects: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Post-Authorization Safety, Tolerability and Immunogenicity Evaluation of HyQvia in Pediatric PIDD Subjects (NCT03116347), a non-randomized phase 4 study. The primary outcome is Safety: Number of Participants With Any Severe Related Treatment-emergent Adverse Events (TEAEs) Per Infusion (Excluding Infections).

2. Clinical Question

The broader study purpose was to collect additional information on safety, tolerability and immunogenicity in pediatric participants with primary immunodeficiency diseases. The listed secondary outcomes include changes in immunoglobulin G and antibody measures, treatment intervals, and local treatment-emergent adverse events. These aims describe what the study was designed to assess; they do not establish that any particular outcome occurred or changed. The registry record does not report results for those secondary outcomes.

3. Trial Design

This was a phase 4, non-randomized, unmasked, single-group study. The registry records enrollment of 42 participants and lists the study status as completed. The recorded start date was 2017-05-30, and the primary completion date was 2021-01-15. The sponsor is listed as Baxalta now part of Shire.

The study concerned children and adolescents with primary immunodeficiency diseases. Participants who had not previously received HyQvia entered Epoch 1, described as a ramp-up period. Epoch 2 included participants previously treated with HyQvia and those who completed the ramp-up period. The record also describes an Epoch 3 safety follow-up for participants meeting specified antibody-titer and adverse-event conditions. Some details of the Epoch 2 description are truncated in the registry record, so the full follow-up and completion rules are not reported there.

The prior-treatment groups shown in the safety information are HyQvia New Starters and HyQvia Pre-treated. These are not randomized treatment arms: prior treatment status defines the grouping, and the record supplies no basis for treating one group as the other's control. Differences between groups could reflect their different histories or other differences not described in the record.

The intervention listing includes HYQVIA, KIOVIG and Cuvitru, each identified as a biological intervention. The record does not establish from that listing alone that the latter products were administered as comparators or explain their role in the study. Allocation was non-randomized and masking was absent. The registry record does not report a protocol-level statistical plan, a sample-size justification, or details of interim analyses.

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: Participants who were treated with HyQvia in Epoch 1 followed by Epoch 2 were referred to as "HyQvia new starters" and participants who started directly in Epoch 2 were referred to as "HyQvia pre-treated". 1 participant from "HyQvia new starters" group discontinued Epoch 2 and entered Epoch 3 due to a severe related adverse event. Participant did not receive HyQvia treatment in Epoch 3. Therefore, no further safety and efficacy data were collected in Epoch 3.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all participants in the full analysis set (enrolled set) who received at least one dose of HyQvia.

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: Safety analysis set included all participants in the full analysis set (enrolled set) who received at least one dose of HyQvia.

6. Primary Endpoint

The registry lists the primary outcome as Safety: Number of Participants With Any Severe Related Treatment-emergent Adverse Events (TEAEs) Per Infusion (Excluding Infections), measured over From start of study drug administration up to 20 months.

The primary endpoint is the number of participants with any severe related treatment-emergent adverse event per infusion, excluding infections. The stated observation period runs from the start of study drug administration up to 20 months. A treatment-emergent adverse event is defined as an event beginning after the first dose, or a pre-existing condition that increased in severity or relationship after the first dose. Events recorded as possibly or probably related to HyQvia count as related for this endpoint.

This endpoint is used to describe an important part of the safety experience during treatment: whether participants experienced a severe event considered related to HyQvia. Excluding infections means infection events are outside this particular endpoint, not necessarily outside all safety monitoring. The endpoint is a participant count, rather than a measure of event severity on a continuous scale or a comparison of treatment effects.

The safety analysis set includes participants in the full analysis set, described as the enrolled set, who received at least one dose of HyQvia. The registry record does not report the primary endpoint count, a denominator for its result, or an inferential estimate. The separate serious-event figures should not be substituted for this primary endpoint: serious events and severe related treatment-emergent events are not defined as interchangeable outcomes in the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends first on matching each result to its endpoint definition and analysis population. The primary endpoint is a participant count for severe HyQvia-related treatment-emergent adverse events, excluding infections. Its analysis population is the safety set: enrolled participants who received at least one dose of HyQvia. The record does not report the number meeting that endpoint or the corresponding analysis details, so an endpoint estimate cannot be reconstructed from the other safety figures.

What does a participant count describe?

A count records how many participants meet a defined event criterion. It is not automatically a rate, a risk estimate, or a comparison between treatments. To interpret a count as a proportion, a relevant denominator and a clear definition of who is included are needed. For time-based rates, information about follow-up time and event timing may also matter. These distinctions are general statistical principles. The primary endpoint is described as a participant count per infusion, but the record does not provide a reported primary result or the details needed to turn it into a rate.

The serious-event information gives counts and numbers at risk within the HyQvia New Starters and HyQvia Pre-treated groups. Those figures are useful as descriptive safety information, but they do not replace the primary endpoint. The event definitions differ: the primary endpoint specifies severity, treatment emergence, relationship to HyQvia and exclusion of infections, whereas the serious-event summary is not defined as that same composite criterion. A number from one endpoint should not be relabeled as a result for another.

Why does the study design matter?

Random allocation, when used, can help balance measured and unmeasured characteristics across treatment groups on average. This study is listed as non-randomized and single-group, with group labels based on prior HyQvia treatment. The groups are therefore not randomized controls. In general, comparisons between non-randomized groups can reflect differences in treatment history or participant characteristics as well as any treatment-related effects. The record does not report an adjusted comparative analysis that addresses such differences.

The study is also listed as unmasked. Masking can reduce some forms of influence on outcome assessment or reporting, depending on the outcome and study procedures. Its absence is relevant context, but the record does not describe endpoint adjudication or other procedures that might affect assessment. No claim about the extent of bias can be made from masking status alone.

What can uncertainty measures add?

In general, a confidence interval gives a range of estimates compatible with the data and statistical assumptions; its width conveys information about precision. A hypothesis test addresses a specified statistical question under a defined model. Neither can be inferred from event counts alone. The registry record lists no inferential analyses, and it does not report an interval or test for the primary endpoint. The registry's absence of an analysis entry does not, by itself, prove that no analysis was ever conducted outside the record.

The sample-size planning illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. They are planning illustrations based on an observed effect, not descriptions of the trial's own design. The record says that non-time-to-event illustrations express participants per arm, while time-to-event illustrations express a total number of events. These assumptions do not turn the non-randomized study groups into randomized arms. They also do not represent observed power or establish that the study was designed around those assumptions. The registry record does not report its own sample-size justification.

Over-dispersion is a general concern when count data vary more than a chosen statistical model expects. If present, it can make uncertainty estimates from a model that assumes less variability too narrow. The registry record does not report a count model, a dispersion estimate, or an analysis of over-dispersion for the primary endpoint. It is therefore not possible to say whether this issue affected the study's analysis.

How should the outcome list be read?

The record lists 41 outcome measures, including secondary measures of immunoglobulin G, antibody levels, treatment intervals and local treatment-emergent adverse events. The list describes planned or registered measurements; it does not establish which results were analyzed or reported. The record lists no analyses. It does not describe a statistical analysis plan, any multiplicity procedure, or which outcomes were prioritized beyond identifying the primary outcome.

Multiplicity is a general issue when several outcomes or tests are considered: the chance of at least one apparently unusual result can increase as more hypotheses are tested. Adjustments or prespecified prioritization can address this in some settings, but the record does not report such procedures. Missing-data methods, rules for incomplete follow-up, and handling of participants who discontinued are also not reported in the registry record. Without those details and the endpoint results, the analyses' robustness and precision cannot be evaluated.

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("HyQvia New Starters", "HyQvia Pre-treated")
n      <- c(23, 19)
events <- c(1, 0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  HyQvia New Starters  23  1  4.3  0.1  21.9  0.8  21.0  1.0  21.1
ARM  HyQvia Pre-treated  19  0  0.0  0.0  17.6  0.0  16.8  0.1  16.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 41 outcome measures, including a primary safety measure and secondary safety and immunogenicity measures. It does not report a multiplicity strategy, such as an adjustment for testing several outcomes, nor does it describe a hierarchy of secondary hypotheses. In general, evaluating many outcomes can make isolated findings harder to interpret because the chance of a seemingly notable result may increase. That is a general statistical concern, not evidence that any particular result in this study is false or was selected after analysis.

The record lists no analyses and does not report the statistical analysis plan. This means that the methods used to summarize outcomes, handle uncertainty, or adjust for participant characteristics are not available in the registry record. The absence of analysis entries does not establish that no analyses took place outside the record. No inferential results are available to assess.

Missing-data handling is also not reported in the registry record. The record does not state how incomplete outcome measurements, missed visits, withdrawals, or changes in follow-up were handled. It therefore cannot establish whether the reported safety figures, or any unreported secondary results, include all expected observations or how missing information might affect interpretation.

The primary safety analysis population is defined as enrolled participants who received at least one dose of HyQvia. The record does not report the size of that set or its relationship to the number contributing to the primary endpoint. This distinction matters because a registry's enrollment count is not necessarily the same as the denominator for every analysis. No missing-data assumptions or population-level sensitivity analyses are reported.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: idiopathic orbital inflammation (5.3%), dental caries (5.3%), inflammatory bowel disease (5.3%), pyrexia (5.3%), pilonidal cyst (5.3%).

The registry lists serious adverse event figures for HyQvia New Starters and HyQvia Pre-treated. The first group has 2 participants with a serious event among 23 at risk; the second has 5 among 19 at risk. These are descriptive safety counts for the groups as labeled in the record. They do not constitute a randomized comparison, since the study is non-randomized and the groups differ by prior HyQvia treatment status.

The serious-event counts should not be confused with the primary endpoint. That endpoint counts participants with severe HyQvia-related treatment-emergent adverse events, excluding infections. The serious-event summary is not defined as satisfying all those criteria. The registry does not report the primary endpoint count, so it cannot be recovered by treating the serious-event figures as equivalent.

The record lists zero deaths for each group. It also lists six serious-event terms, each at 5.3%. Those terms are reported as safety information, but the record does not establish from the listing alone that each was related to HyQvia or met the primary endpoint definition. The counts and terms are descriptive; they do not establish causation or provide a complete comparison of safety between treatment histories.

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

The registry record documents a completed phase 4 study focused on safety, tolerability and immunogenicity of HyQvia in pediatric participants with primary immunodeficiency diseases. It describes a primary safety endpoint and gives serious adverse event counts for participants grouped by prior HyQvia treatment. Those details help clarify what the study set out to examine and how some safety information was organized.

The record does not report the primary endpoint result or inferential analyses. It therefore does not establish the observed number of participants with severe related treatment-emergent adverse events, the precision of that result, or how it compares with another treatment. The serious-event counts are not interchangeable with the primary endpoint, and the two prior-treatment groups are not randomized control groups.

These data also do not establish that HyQvia caused any particular listed event. The registry's primary definition includes events recorded as possibly or probably related, but the serious-event terms are not individually classified in the information. The absence of a reported outcome cannot be interpreted as a zero count or as evidence that no event occurred.

The record's outcome list includes measures of immunoglobulin and specific antibody levels, treatment intervals, and other safety outcomes. Their results are not reported in the registry record for interpretation. Accordingly, the stated study aims should not be mistaken for findings. The registry record supports a limited descriptive account of design and selected serious-event figures, not a broad judgment about treatment effects, comparative safety, or immunogenicity.

14. Why This Trial Matters Statistically

This study illustrates why a clear endpoint definition is essential in clinical safety reporting. Its primary endpoint is specific: a participant count for severe, HyQvia-related treatment-emergent adverse events, excluding infections. A nearby safety summary of serious adverse events may appear similar, but the registry does not define it as the same outcome. Keeping endpoint definitions separate prevents one safety count from being treated as a substitute for another.

The design also matters for interpretation. Participants were not randomly allocated, and the listed groups reflect prior HyQvia treatment status. Such groups can be informative for describing safety experience, but they are not equivalent to randomized arms. A descriptive difference between them would not, on its own, identify a treatment effect.

The record further shows why planned outcomes and reported findings must be distinguished. It lists 41 outcome measures, yet no analyses or primary endpoint result are reported in the information available for interpretation. A long outcome list indicates breadth of measurement, not a complete set of findings. Without analysis details, uncertainty estimates and missing-data methods, readers cannot assess the precision or robustness of the stated outcomes.

Finally, the record offers a useful example of how post-authorization research can be framed around additional safety, tolerability and immunogenicity information while still leaving important statistical questions unresolved in the registry entry. Study status and endpoint definitions alone do not supply outcome evidence. Transparent reporting of results and analysis methods is needed to determine what the collected observations show.

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 most important limitation for interpreting the posted results is that the registry record does not report the primary endpoint result. It also does not provide an inferential estimate, confidence interval, or test for that endpoint. The serious adverse event figures cannot fill this gap because they are not defined as the primary endpoint.

The study was non-randomized, unmasked and single-group. The two groups in the serious-event summary are based on prior HyQvia treatment status, not random allocation. Their counts therefore cannot support a causal comparison. The record does not report adjustment for group differences or details about how adverse events were assessed.

The registry describes a safety analysis set consisting of enrolled participants who received at least one dose of HyQvia, but does not report how many participants contributed to the primary endpoint result. It does not report missing-data handling, the treatment of withdrawals, or whether follow-up was complete for each outcome. The Epoch 2 description is also truncated, limiting interpretation of some follow-up and completion rules.

The record lists 41 outcome measures but provides no analysis entries or statistical analysis plan. It does not report multiplicity procedures, model choices, or a sample-size justification for the trial. The sample-size planning illustrations are not the study's design rationale and are not observed power. Together, these omissions limit assessment of precision, robustness, and the full safety and immunogenicity findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Post-Authorization Safety, Tolerability and Immunogenicity Evaluation of HyQvia in Pediatric PIDD Subjects — NCT03116347.
• Registry record last updated 2023-01-11; status last verified 2022-04.
• Results first posted 2023-01-11.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry describes NCT03116347, a completed phase 4, non-randomized, unmasked, single-group study of HyQvia in pediatric participants with primary immunodeficiency diseases. Enrollment was 42. The recorded study start was 2017-05-30, and primary completion was 2021-01-15. The stated aim was to collect additional safety, tolerability and immunogenicity information.

The primary endpoint was the number of participants with severe HyQvia-related treatment-emergent adverse events per infusion, excluding infections, during the period from study drug initiation up to 20 months. Its result is not reported in the registry record. The record lists serious-event counts of 2 among 23 at risk for HyQvia New Starters and 5 among 19 at risk for HyQvia Pre-treated; these groups are not randomized comparators. No analyses are reported, and the registry record does not describe missing-data or multiplicity methods.