A Study to Assess the Safety and Effectiveness of Palivizumab Administered to Children at High Risk of Severe Respiratory Syncytial Virus (RSV) Infection in the Russian Federation and the Republic of Belarus: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Assess the Safety and Effectiveness of Palivizumab Administered to Children at High Risk of Severe Respiratory Syncytial Virus (RSV) Infection in the Russian Federation and the Republic of Belarus (NCT02968173), a na phase 3 study. The primary outcome is Percentage of Participants With RSV Hospitalization.

2. Clinical Question

The question is descriptive in this design: it concerns the frequency of a defined clinical event among children receiving palivizumab. Without a concurrent control group, the study cannot directly estimate how that frequency would compare with the frequency under another intervention or without palivizumab. The primary endpoint and follow-up period are identified, but the percentage of participants hospitalized for RSV and its 95% confidence interval are not reported in the registry record. The record reports enrollment of 50 participants. It also lists outcomes describing RSV hospitalization burden and respiratory support, including hospitalization days, intensive care use, supplemental oxygen, and mechanical ventilation.

3. Trial Design

This is a prospective, international, multicenter, open-label, non-controlled study of palivizumab in children at high risk of severe RSV infection. The registry classifies it as Phase 3, and the study summary describes it as Phase 3b. The study took place in the Russian Federation and the Republic of Belarus. Its status is completed, and the record reports enrollment of 50.

All participants were assigned to the single palivizumab group described in the record. The intervention was an intramuscular injection every 30 days beginning at Day 0, for a total of 3-5 injections. The number of injections depended on when a participant enrolled during the RSV season. The study was open-label, and the record gives masking as none. Allocation is listed as not applicable, consistent with the single-group, non-controlled design.

The primary outcome was the percentage of participants with RSV hospitalization over approximately 6 months. The registry also lists outcomes describing hospitalization duration and the use of supplemental oxygen, intensive care, and mechanical ventilation. These outcomes address different aspects of RSV illness burden, but the registry record does not report their numerical results.

The record lists a start date of 2016-11-09 and a primary completion date of 2017-07-13. It does not report the protocol details needed to assess how the target enrollment was chosen, how follow-up or outcome ascertainment was managed in practice, or whether any interim analyses were planned. The absence of a control group is central to interpretation: observed outcomes in this cohort can be described, but treatment effects relative to an alternative cannot be isolated from other explanations using this design alone.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With RSV Hospitalization, measured over Approximately 6 months.

The primary endpoint is the percentage of participants with RSV hospitalization during approximately 6 months of follow-up. It measures the proportion of the study group experiencing an event defined by the registry, rather than the duration or severity of every respiratory illness. The definition includes a respiratory or cardiac hospitalization with a positive RSV test; new respiratory or cardiac symptoms in a child already hospitalized, together with objective worsening and a positive RSV test; or a death demonstrated to have been caused by RSV.

A binary endpoint records whether each participant did or did not meet the specified event definition during the stated period. Reporting the percentage gives a direct description of the event frequency in the study group. The accompanying 95% confidence interval, if reported, would convey uncertainty around that estimated percentage: a narrower interval generally indicates greater precision, while a wider interval indicates less precision. The interval would not by itself establish a causal effect or remove limitations arising from study design.

RSV hospitalization is relevant to the study question because it captures a consequential event associated with RSV illness in this high-risk population. The registry also identifies measures of hospitalization days, intensive care, oxygen use, and mechanical ventilation, which describe other dimensions of illness burden. The primary event percentage and its 95% confidence interval are not reported in the registry record, so the endpoint's observed frequency and precision cannot be described from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods described in the registry record are limited. It identifies the primary outcome as the percentage of participants with RSV hospitalization and specifies a 95% confidence interval. It does not report a named statistical procedure for calculating that interval, a detailed analysis plan, or numerical primary results. The points below explain the general statistical ideas relevant to the listed outcome; they are not a claim about unreported procedures used in the study.

What does a percentage endpoint represent?

For a binary outcome, each participant is classified according to whether the event occurred during the defined follow-up period. The percentage is a summary of the event frequency in the analysis group. The clinical meaning depends on the endpoint definition, the population being described, and the period of observation. Here, the registry defines RSV hospitalization using specified hospitalization, testing, symptom-worsening, and death criteria. The record does not report the primary event count, percentage, or analysis population, so these cannot be reconstructed from the registry information.

What does a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty associated with an estimate. A point estimate alone gives a single summary of the observed frequency; an interval helps show how much uncertainty remains because the study includes a finite group of participants. Interval width depends on the amount of information in the data and on the calculation method. A confidence interval is not a measure of clinical importance, and it does not establish a causal effect. The registry specifies a 95% confidence interval for the primary endpoint, but the interval itself is not reported in the registry record.

Why does the single-group design matter?

A single-group study describes outcomes among participants who received the study intervention. A concurrent comparator can help estimate how outcomes differ under another treatment or care condition, subject to the design and analysis. This study is described as non-controlled, with a single-group model and no masking. It therefore cannot provide a randomized between-group contrast. Even if an event frequency were reported, interpreting it as an effect attributable to palivizumab would require assumptions that a single-group design cannot test directly. The registry record does not report a comparative statistical analysis.

What can the safety counts tell readers?

Counts of participants affected by events are descriptive summaries. They communicate how many participants were recorded as affected within the stated observation window, but interpretation also depends on event definitions, collection procedures, follow-up, and the population included in the denominator. The record reports 50 participants at risk for each listed safety window and gives counts of serious and other treatment-emergent adverse events, as well as deaths. Those values do not form a comparison against another group. The record does not report additional details about event adjudication or a statistical comparison of safety outcomes.

How should planning illustrations be understood?

Any sample-size illustrations associated with the posted results are planning scenarios, not evidence that the study had a particular probability of detecting an effect. The stated assumptions describe two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. These are hypothetical inputs for a planning exercise. The record describes the underlying trial as single-group, so a two-arm illustration is not the trial's observed design. Such scenarios are not observed power, do not replace a protocol-based sample-size justification, and should not be read as observed trial outcomes. The registry record does not report the original sample-size justification.

For a binary outcome, assumptions about the event frequency and the effect targeted can materially affect planning estimates. General sample-size calculations depend on the planned design, allocation, significance criterion, desired power, and analysis method. A planning scenario based on an observed effect is especially dependent on the observed estimate and may be unstable when that estimate is imprecise. No additional scenario values or the underlying primary outcome estimate are reported in the registry record, so no independent numerical assessment of those illustrations is possible from the registry information.

Statistical significance, if reported, would answer a different question from precision or clinical importance. A p-value is interpreted relative to a specified null hypothesis and model; it does not give the probability that a treatment works, and it cannot establish causation in a non-controlled design. The registry record reports no analysis results or p-values. It also does not state whether planned analyses included adjustment for baseline characteristics, subgroup analyses, or sensitivity analyses. Those methods should not be inferred from the endpoint description alone.

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("Children at High Risk of Severe RSV Infection")
n      <- c(50)
events <- c(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  Children at High Risk of Severe RSV Infection  50  0  0.0  0.0  7.1  0.0  7.1  0.0  7.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary endpoint and several secondary outcomes. These include RSV-hospitalization days, the percentage of participants receiving supplemental oxygen while hospitalized, hospitalization days with increased oxygen requirements, intensive care admissions and stay, and mechanical ventilation. Together, the outcomes describe more than one aspect of RSV illness and resource use. The registry record does not report a statistical testing hierarchy, a family of hypotheses, or any adjustment for multiple comparisons.

In general, when many outcomes are tested, the chance of at least one apparently notable result can increase. A prespecified hierarchy or multiplicity adjustment can help control that issue, but whether either was used is not reported in the registry record. The absence of that information does not show that no such plan existed; it means the registry record does not document it.

Missing-data handling and analysis populations are also not reported in the registry record. It does not specify whether the primary analysis included all enrolled participants, only participants with complete follow-up, or another defined group. It does not describe how missing endpoint assessments, withdrawal, or incomplete follow-up were addressed. The enrollment figure alone does not identify the denominator used for each outcome.

These omissions limit assessment of how robust the reported results would be to alternative assumptions about missing observations, and how any secondary findings should be interpreted alongside the primary endpoint. Because numerical outcome analyses are not reported, there are no posted estimates to evaluate for these issues.

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

Serious events with the highest arm-level rate: tachycardia paroxysmal (2.0%), bronchitis (2.0%), bronchitis viral (2.0%), nasopharyngitis (2.0%), pneumonia (2.0%).

The registry reports serious treatment-emergent adverse-event information for two observation windows: within 30 days and within 100 days. For each window, 50 participants are listed as at risk, 6 as affected by a serious event, 0 as affected by another treatment-emergent adverse event, and 0 deaths. These are counts recorded for the study group; they are not comparative estimates of risk because the study had no control group.

The registry also lists serious event terms with a reported percentage of 2.0% for each term: tachycardia paroxysmal, bronchitis, bronchitis viral, nasopharyngitis, pneumonia, and respiratory tract infection viral. These entries are descriptive. The registry record does not provide enough information to infer from the term list alone whether events overlapped within participants or to determine individual event-level causality.

Serious adverse events and other treatment-emergent adverse events are distinct reporting categories. A count should not be interpreted as an estimate of comparative safety, and a zero count in the listed category does not establish that no other health events occurred. The registry record does not report further details about event ascertainment, severity grading, or attribution procedures. The counts therefore describe what is posted, within the stated windows, rather than proving that the intervention caused or prevented an event.

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

The record establishes that a completed, prospective, open-label, non-controlled study evaluated palivizumab in children described as being at high risk of severe RSV infection. It identifies RSV hospitalization over approximately 6 months as the primary endpoint and gives the event definition. It also reports enrollment of 50 and selected safety counts. Those details help define what the study set out to assess and what safety information was posted.

The primary endpoint result itself is not reported in the registry record. Neither the percentage of participants with RSV hospitalization nor its 95% confidence interval is available in the posted information. As a result, the observed primary event frequency and its statistical precision cannot be stated. Numerical results for the listed secondary outcomes are also not reported in the registry record.

Even if a primary event percentage were available, the single-group design would describe outcomes among participants receiving palivizumab rather than establish what would have happened to comparable participants under a different condition. The design includes no control group, and allocation is listed as not applicable. Thus, the posted information cannot supply a direct comparative treatment effect. Open-label conduct and unreported details about outcome assessment, missing data, and analysis populations are additional considerations when judging what a result could mean.

The serious adverse-event counts provide descriptive safety information for the two stated time windows. They do not show how those counts compare with a control group, and they do not alone establish causation. The record does not report enough information to make broader claims about safety beyond the listed counts and terms.

Accordingly, the registry record supports a description of study design, endpoint definitions, and selected safety observations. It does not support a conclusion about the magnitude or precision of the primary endpoint, or a causal claim that palivizumab did or did not change RSV hospitalization risk.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the difference between describing an outcome and estimating a comparative treatment effect. The registry describes a single-group, non-controlled study and defines RSV hospitalization as its primary endpoint. A percentage of participants meeting that definition would summarize the event frequency in the study group, but without a comparator it would not directly quantify a difference attributable to treatment.

The endpoint definition also matters. It combines specified forms of hospitalization, worsening symptoms with a positive RSV test in an already hospitalized child, and a death demonstrated to be caused by RSV. Clear outcome criteria are essential for interpreting any event percentage, because the estimate is meaningful only in relation to the population, follow-up period, and event rules used to generate it. Here, the primary follow-up is approximately 6 months, but the numerical endpoint result is not reported in the registry record.

The record names a 95% confidence interval, highlighting the value of reporting uncertainty alongside an estimate. A point estimate without an interval can conceal substantial imprecision; an interval helps readers judge how much information the data provide. Since neither the primary estimate nor its interval is reported, that assessment cannot be made.

The study also lists several secondary outcomes covering hospitalization duration, respiratory support, and intensive care. These outcomes broaden the description of illness burden but raise questions about multiplicity and prespecification when statistical findings are reported. The registry does not document a multiplicity strategy or analysis hierarchy. Finally, the safety counts illustrate why descriptive event summaries should be kept distinct from comparative evidence: counts from one group alone do not show whether event occurrence differs from another treatment or background risk.

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 main limitation for interpreting effectiveness is the absence of a control group. Because the study is single-group and non-controlled, it cannot provide a direct comparison with another treatment or an untreated group. Outcomes observed in the study group cannot by themselves separate treatment effects from other influences.

The registry record does not report the primary endpoint percentage or its 95% confidence interval. It also does not report numerical results for the listed secondary outcomes. This prevents assessment of the observed event frequency, uncertainty, or the distribution of outcomes across the study period.

The study was open-label, with masking listed as none. The registry record does not report further information about outcome assessment procedures or whether any steps were used to reduce the influence of treatment knowledge. It also does not report the analysis population, handling of missing data, or details of participant follow-up for each outcome.

Although the record reports enrollment of 50, it does not report the original sample-size justification or explain how that enrollment target was selected. A sample-size planning illustration based on an observed effect is not a substitute for the protocol's design rationale and is not observed power. The registry also does not report whether interim analyses, subgroup analyses, sensitivity analyses, or multiplicity adjustments were planned or conducted.

These limitations concern what can be determined from the registry record; they do not establish that unreported procedures were absent. They constrain interpretation of the posted information, particularly any attempt to draw causal or comparative conclusions.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study to Assess the Safety and Effectiveness of Palivizumab Administered to Children at High Risk of Severe Respiratory Syncytial Virus (RSV) Infection in the Russian Federation and the Republic of Belarus — NCT02968173.
• Registry record last updated 2018-03-13; status last verified 2017-07.
• Results first posted 2018-03-13.
• 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 a completed, prospective, international, multicenter, open-label, non-controlled Phase 3 study, also described in the study summary as Phase 3b. It assessed palivizumab in children at high risk of severe RSV infection in the Russian Federation and the Republic of Belarus. The reported enrollment is 50.

Palivizumab was given by intramuscular injection every 30 days beginning at Day 0, for a total of 3-5 injections depending on enrollment timing during the RSV season. The primary outcome was the percentage of participants with RSV hospitalization over approximately 6 months, with a 95% confidence interval specified. The primary outcome result and interval are not reported in the registry record.

The registry lists secondary outcomes concerning hospitalization days, supplemental oxygen, intensive care, and mechanical ventilation. For safety, it lists 6 participants with serious treatment-emergent adverse events within each of the two stated windows, 0 with other treatment-emergent adverse events, and 0 deaths. These are descriptive counts from a single-group study, not comparative estimates.