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 A Study of Intravenous Zanamivir in the Treatment of Hospitalized Patients With Influenza Infection (NCT01527110), a na phase 3 study. The primary outcome is Number of Participants With Any Adverse Event (AE), Drug-related AE, Grade 3 and Grade 4 AE, Grade 3 and 4 Drug-related AE , AE Leading to Discontinuation of Study Drug or From Study, Serious AE (SAE), Drug-related SAE, Fatal AE and Drug-related Fatal AE.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01527110 |
| Phase | Phase 3 |
| Condition | Influenza, Human |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
Hospitalized participants with laboratory-confirmed influenza infection were eligible for the study. The registry record identifies the condition as human influenza and reports enrollment of 21 participants. The safety population is defined as participants who received at least one dose of intravenous zanamivir. Further participant characteristics, such as age distribution, illness severity, or the criteria used to confirm infection, are not reported in the registry record.
Intervention
The intervention was intravenous zanamivir, described as 600mg twice daily for 5 days. The study evaluated this regimen in an open-label setting. The registry record does not report adherence, dose interruptions, or the extent to which participants completed the intended course.
Comparator
There was no comparison group. The trial was single arm, with no randomized allocation and no masking. Consequently, the registry results do not provide a like-for-like control group against which to compare adverse events, clinical course, or outcomes over time.
Primary question
The primary outcome concerns the number of participants experiencing listed adverse-event categories: any adverse event, drug-related adverse event, Grade 3 or Grade 4 adverse event, severe drug-related adverse event, events leading to discontinuation, serious adverse events, drug-related serious events, fatal events, and drug-related fatal events. These are safety questions rather than a direct comparison of treatment effects. The registry record also lists secondary outcomes concerning clinical response, symptoms, activity, respiratory support, hospital and ICU stay, and viral susceptibility. Results for those secondary outcomes are not reported in the registry record in the registry record for this analysis.
3. Trial Design
This was a Phase 3, open-label, multicentre, single-arm study of intravenous zanamivir in hospitalized patients with confirmed influenza infection. The registry record reports enrollment of 21 participants and identifies GlaxoSmithKline as the sponsor. The intervention was described as 600mg of intravenous zanamivir twice daily for 5 days. There was no randomized allocation, masking, or concurrent control arm. The study status is recorded as completed.
In a single-arm study, participants receive the intervention under evaluation, and outcomes are described within that group. This design can document events observed during treatment and follow-up, but it cannot isolate the effect of treatment from the course of illness, other care, or other influences. Because there is no control arm, observed event counts do not establish how often similar events would have occurred without the study intervention.
The registry record gives a primary safety timeframe from start of treatment on Day 1 up to follow-up on Day 33. It defines the safety population as participants who received at least one dose. The adverse-event summary lists 21 participants at risk in the zanamivir group. More detailed information about participant flow, treatment exposure, protocol deviations, or follow-up completeness is not reported in the registry record.
The listed secondary outcomes include times to fever absence, improved respiratory status and other clinical measures, clinical response, return to pre-morbid activity, use and duration of respiratory support, ICU stay, hospital stay, and viral susceptibility. The registry lists 42 outcome measures, but detailed numerical results for these outcomes are not reported in the registry record in the registry record. The record lists no analysis entries. The protocol’s statistical analysis plan, sample-size justification, and any planned interim analyses are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: A total of 21 hospitalized Japanese participants with laboratory confirmed influenza were enrolled to receive intravenous (IV) zanamivir 600 milligram (mg) twice daily (BID) for 5 days. The course was extended for up to 5 additional days based on ongoing viral shedding or clinical symptoms requiring treatment.
Overall Study
| Stage | Zanamivir 600 mg BID |
|---|---|
| STARTED | 21 |
| COMPLETED | 20 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Zanamivir 600 mg BID |
|---|---|
| Adverse Event | 1 |
Analysis population for the primary outcome, as defined in the registry: Safety Population comprised of all participants who received at least one dose of IV zanamivir.
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.
| Characteristic | Unit | Zanamivir 600 mg BID |
|---|---|---|
| Participants analysed | 21 | |
| Age, Continuous | Years | 67.3 (SD 23.58) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 12 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 21 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Any Adverse Event (AE), Drug-related AE, Grade 3 and Grade 4 AE, Grade 3 and 4 Drug-related AE , AE Leading to Discontinuation of Study Drug or From Study, Serious AE (SAE), Drug-related SAE, Fatal AE and Drug-related Fatal AE, measured over Start of treatment (Day 1) up to follow-up (Day 33).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary outcome is framed as counts of participants experiencing a range of adverse events during treatment and follow-up. It includes any adverse event, events judged drug-related, Grade 3 and Grade 4 events, events leading to discontinuation of study drug or withdrawal from the study, serious adverse events, fatal events, and drug-related versions of several categories. These categories describe different aspects of safety; they should not be treated as one combined outcome.
An adverse event is defined in the registry as an untoward medical occurrence temporally associated with use of a medicinal product, whether or not it is considered related to that product. A serious adverse event is defined by consequences such as death, life-threatening events, hospitalization or prolonged hospitalization, disability or incapacity, congenital anomaly, or other specified serious circumstances. The registry says that severity grading and judgments about drug relationship were made by the investigator.
Counting participants with events is useful for describing how many people in the observed safety population experienced a safety event. It is different from counting every event: a participant may experience more than one event, while a participant count ordinarily records that person once within a defined category. The posted safety summary does not provide every primary-outcome category’s numerical count, so the full primary safety profile cannot be reconstructed from the figures available in the registry record. Counts from this single group also cannot establish comparative risk.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a small, single-arm safety study and reports 21 participants enrolled. In the adverse-event group summary for zanamivir 600 mg BID, 21 participants are listed as at risk. The summary records 4 participants with serious adverse events and 4 participants in the other adverse-event category. It also records 1 death. These are descriptive counts from the treated group, not estimates of a difference relative to an untreated or active-control group.
The registry lists four serious adverse-event terms among its top terms: bacterial pneumonia, respiratory tract infection, hyperthyroidism, and decreased haemoglobin. Each is reported as 4.8%. These percentages describe the registry’s reported terms; the information does not establish that zanamivir caused the events. The record states that drug relationship was assessed using investigator judgment, but the specific number of drug-related serious events and other drug-related categories is not reported in the registry record in the registry record for this analysis.
In a single-arm study, an observed event may reflect the underlying illness, coexisting conditions, other treatments, or the intervention, among other possibilities. Without a control group and a comparative analysis, the relative contribution of these factors cannot be determined from these counts. The same caution applies to the death: the record reports 1 death but does not provide enough detail to attribute its cause or relationship to treatment.
The registry lists numerous secondary clinical and resource-use outcomes, but their numerical results are not reported in the registry record in the registry record for this analysis. There are no posted analysis entries. No confidence intervals, p-values, or adjusted estimates are present in the record details for these outcomes. Consequently, statistical precision and comparative evidence cannot be assessed from the stated safety figures alone.
General statistical interpretation: a count describes the number of participants meeting a stated event definition in the observed group. Its interpretation depends on the population included, the time period assessed, how events were defined and collected, and whether follow-up was complete. A count in a small cohort can be informative as a description of that cohort, but it may be unstable as an estimate of event frequency in a wider population. No additional frequency estimates should be inferred from the reported counts.
The design and results support a narrow reading: the registry records safety events during a defined treatment and follow-up period in a single group of hospitalized participants. They do not provide a controlled estimate of treatment effect, and the available outcome details are insufficient to evaluate all listed safety categories or secondary clinical outcomes.
9. Statistical Methods Explained
The registry identifies the primary outcome as a count of participants, rather than a continuous measurement or a time-to-event estimate. It groups several safety concepts under the primary outcome title, including any adverse event, severity grades, serious events, discontinuations, and fatal events. These categories are related but distinct. A participant might meet more than one category, and the record does not state that the categories are mutually exclusive or intended to be added together.
What does a participant count describe?
A participant count records how many people experienced an event meeting a defined category during the stated observation period. It is not the same as an event count, since one participant may have multiple events. It is also not a rate per unit of time: the listed count does not itself account for differences in how long participants were followed or exposed. The registry gives the primary safety timeframe as Day 1 through Day 33, but detailed individual follow-up and exposure information is not reported in the registry record.
The safety population is defined as all participants who received at least one dose of intravenous zanamivir. Defining the population this way focuses safety reporting on people exposed to the study drug. The group summary lists 21 participants at risk. Further details on the number who started treatment, dose completion, withdrawals, and missing safety assessments are not reported in the registry record.
How should event categories be interpreted?
The registry’s adverse-event definition includes untoward medical occurrences temporally associated with a medicinal product, regardless of whether they are considered related to that product. Thus, an adverse event is not automatically an adverse reaction. The registry separately identifies drug-related events, with the judgment made by the investigator. This distinction matters because an event may occur after treatment begins without being caused by treatment.
Seriousness and severity are also different concepts. Seriousness is defined by outcomes or consequences, including death, life-threatening events, or hospitalization. Severity refers to grading; the registry describes Grade 3 as severe and Grade 4 as potentially life-threatening. A serious event is not necessarily Grade 3 or Grade 4, and a severe event does not necessarily meet the registry’s seriousness criteria. The primary outcome lists these categories separately, so they should be read separately.
What can an open-label, single-arm design show?
General statistical explanation: an open-label study does not mask participants or investigators to the treatment being given. A single-arm design has no parallel comparator group. Such a design can describe outcomes recorded among treated participants, but it does not estimate a between-group contrast. A comparison with an external or historical group would require additional information and assumptions; no such comparison is reported in the registry record.
Without a control arm, observed events cannot be separated from the expected events associated with influenza, hospitalization, coexisting illness, or other care. Open-label assessment can also leave room for differences in event recognition or classification when judgment is involved. The registry notes that severity and drug relationship were based on investigator judgment. It does not report further details of adjudication or independent review.
What is statistical precision?
General statistical explanation: a confidence interval expresses uncertainty around an estimate under a specified statistical method. A narrow interval indicates greater precision than a wide interval, while neither by itself establishes causality or clinical importance. The registry record details available for this analysis do not include confidence intervals or other uncertainty estimates for the safety counts. Precision therefore cannot be evaluated using an interval-based measure from the reported material.
Similarly, a p-value addresses compatibility between data and a stated statistical model or null hypothesis; it is not a measure of the probability that a treatment works. No p-values or posted analysis entries are reported in the registry record. The absence of these statistics means that inferential claims should not be made from the displayed event counts alone.
What do sample-size illustrations mean?
General statistical explanation: planning calculations describe the sample size that would be needed under chosen assumptions to detect an effect of a specified size with a chosen error rate and power. They are not observed results, and they are not evidence that a study had a particular probability of finding a result after it was conducted. The registry record does not report the trial’s own sample-size justification. Any planning illustration based on an observed effect is distinct from the original design rationale and should not be read as observed power.
The assumptions described for planning illustrations include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such assumptions describe a hypothetical comparison, not this single-arm trial. They do not convert the study into a randomized comparison or supply a control outcome that the trial did not collect. The record does not report that these assumptions were used to plan the trial.
Finally, the registry lists 42 outcome measures and no analysis entries. It does not report how multiplicity was addressed, how missing observations were handled, whether analyses were adjusted, or which analysis populations were used beyond the safety-population definition. Those omissions constrain interpretation: the event definitions and counts can be described, but the full analysis process cannot be verified from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 42 outcome measures, including the primary safety outcome and multiple secondary clinical, respiratory-support, hospital-use, and viral-susceptibility outcomes. When a study assesses many outcomes, the chance of at least one apparently unusual finding can increase if each is tested separately. General statistical practice may address this through prespecified outcome hierarchy, adjustment, or cautious interpretation, but the registry record does not report a multiplicity plan or identify any adjustment method.
The record lists no analysis entries. It does not report whether hypothesis tests were planned for the primary categories or secondary outcomes, whether estimates were adjusted for covariates, or how any interim analyses were handled. Interim analyses and the statistical analysis plan are not reported in the registry record. Therefore, no inference about the planned inferential framework can be made.
Missing-data handling is also not reported in the registry record. The safety population includes participants who received at least one dose, but the available information does not state whether all participants completed follow-up through Day 33, how incomplete assessments were treated, or whether missing observations were imputed or excluded. These details matter because the number observed in each category can depend on the completeness and duration of event surveillance.
The record defines the safety population but does not report other analysis populations, such as populations for efficacy or clinical-response outcomes. It also does not report participant-level data or sufficient outcome detail to assess consistency across analysis sets. These unknowns do not change the reported counts; they limit assessment of how those counts were generated and how comprehensively the planned outcomes were analyzed.
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 |
|---|---|---|---|
| Zanamivir 600 mg BID | 4 | 21 | 19.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Zanamivir 600 mg BID | 1 of 21 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Zanamivir 600 mg BID | 4 of 21 |
Most frequent serious adverse event terms
| Event term | Organ system | Zanamivir 600 mg BID |
|---|---|---|
| Pneumonia bacterial | Infections and infestations | 1 of 21 |
| Respiratory tract infection | Infections and infestations | 1 of 21 |
| Hyperthyroidism | Endocrine disorders | 1 of 21 |
| Haemoglobin decreased | Investigations | 1 of 21 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Zanamivir 600 mg BID |
|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 4 of 21 |
| Pyrexia | General disorders | 2 of 21 |
Serious events with the highest arm-level rate: pneumonia bacterial (4.8%), respiratory tract infection (4.8%), hyperthyroidism (4.8%), haemoglobin decreased (4.8%).
The adverse-event summary lists 21 participants at risk in the zanamivir 600 mg BID group. It records 4 participants with serious adverse events, 4 participants in the other adverse-event category, and 1 death. The serious-event terms reported at 4.8% each are bacterial pneumonia, respiratory tract infection, hyperthyroidism, and decreased haemoglobin. These are descriptions of events recorded in the study group, not proof that the study drug caused them.
The registry defines serious events by outcomes such as death, life-threatening events, or hospitalization, and says that investigators judged event severity and relationship to drug. The available figures do not give all the separate primary-outcome counts, including every drug-related, Grade 3 or Grade 4, discontinuation, and fatal-event category. Those detailed category results are not reported in the registry record in the registry record for this analysis.
The serious-event summary should not be interpreted as a comparison with background risk. There is no control group, and no adjustment for illness severity or other factors is reported. Nor does the listing establish that each participant had only one event. The reported death is a count, not an attribution: its cause and relationship to treatment are not reported in the registry record in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record documents a completed, open-label, single-arm study of intravenous zanamivir in hospitalized participants with confirmed influenza. It reports enrollment of 21 participants and lists safety events observed in the treatment group. In the group summary, 4 participants are recorded with serious adverse events, 4 in the other adverse-event category, and 1 death. These figures describe what was recorded in this cohort over the stated safety period.
They do not establish that zanamivir caused any particular event, nor do they show whether the event counts were higher or lower than they would have been without treatment. A control group would be needed for a direct concurrent comparison, and the trial did not include one. Investigator judgments about drug relationship are part of the registry’s event classification, but those judgments do not substitute for a randomized comparison.
The figures also do not establish the complete safety profile. Several primary categories are named, but their individual results are not reported in the registry record in the registry record for this analysis. Numerical results for the listed secondary outcomes are likewise not reported. Without those data, the clinical course, response times, respiratory-support use, length of stay, and viral susceptibility cannot be evaluated from this record summary.
General statistical interpretation: a result can be described accurately while remaining uncertain in scope. Counts from a small, uncontrolled cohort are useful as observations about the people enrolled, but their precision and generalizability depend on factors such as follow-up completeness, participant characteristics, and the way events were collected. The registry record does not report enough information to assess all of these factors.
The appropriate conclusion is therefore limited to the design and the reported observations: safety events were recorded in a single group treated with intravenous zanamivir, and the available the registry entries do not support a comparative treatment-effect conclusion. Absence of a reported analysis is not evidence that no event occurred; it means that the corresponding result is not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically important because it illustrates the difference between documenting events and estimating comparative effects. A single-arm study can provide structured observations of safety in a defined group, including serious-event categories and investigator judgments about drug relationship. Those observations can be useful for describing what happened during the study’s treatment and follow-up period.
At the same time, the absence of a control group changes the questions the data can answer. Event counts from treated participants do not reveal what would have happened under another treatment or without the study intervention. This distinction is especially important in hospitalized participants with influenza, where the underlying illness and other care may also be relevant to observed events. The registry record does not report a comparative analysis that could separate those influences.
The record also highlights why outcome definitions matter. Adverse events, drug-related events, serious events, severity grades, discontinuations, and fatal events are not interchangeable. Their separate interpretation depends on definitions, ascertainment, and population. The record specifies definitions and the safety population, but several category-specific results and details about follow-up are not reported in the registry record.
Finally, the listed range of secondary outcomes and the absence of posted analysis entries show why a registry record should be read as a record of registered design and reported results, not as a complete statistical report unless the relevant analysis details are available. The record identifies outcomes of interest, but it does not provide the full numerical results or inferential methods needed to assess them. Keeping these boundaries clear helps distinguish descriptive evidence from causal or comparative conclusions.
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 the single-arm design. Without a control group, the reported event counts cannot estimate a comparative risk or distinguish events associated with the illness and hospitalization from events associated with treatment. The open-label design also means treatment was not masked, and the registry says that severity and drug relationship involved investigator judgment. Details of independent event review are not reported in the registry record.
The study enrolled 21 participants, limiting the amount of safety experience represented by the cohort. The adverse-event summary reports 21 at risk, but further details about treatment completion, participant flow, exposure, withdrawals, and completeness of follow-up are not reported in the registry record. The primary timeframe extends from Day 1 through Day 33; longer-term safety outcomes are not described in the registry record.
The primary outcome title names multiple safety categories, but the available results do not include numerical counts for every category. The registry also lists 42 outcome measures, while numerical results for the listed secondary outcomes and analysis entries are not reported in the registry record. A statistical analysis plan, sample-size justification, missing-data approach, multiplicity strategy, and interim-analysis details are not reported.
The serious adverse-event term list gives four terms, each reported as 4.8%, but the available record does not establish causation or provide the detail needed to assess event overlap, participant-level characteristics, or comparative context. The reported death likewise cannot be attributed on the basis of the registry entries. These limitations mean the registry supports a descriptive account of selected safety observations, not a full assessment of comparative efficacy or safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of Intravenous Zanamivir in the Treatment of Hospitalized Patients With Influenza Infection — NCT01527110.
- Registry record last updated 2018-02-22; status last verified 2017-07.
- Results first posted 2018-02-22.
- 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
NCT01527110 is a completed Phase 3, open-label, multicentre, single-arm study sponsored by GlaxoSmithKline. It evaluated intravenous zanamivir, described as 600mg twice daily for 5 days, in hospitalized participants with confirmed influenza infection. The registry reports enrollment of 21 participants and defines the safety population as those who received at least one dose.
The primary outcome concerns participant counts across several adverse-event categories from Day 1 through Day 33. The adverse-event summary lists 21 participants at risk, 4 with serious adverse events, 4 in another adverse-event category, and 1 death. Four serious-event terms are listed at 4.8% each. The study had no control group, and the registry record lists no analysis entries.
Detailed results for all primary categories, numerical secondary-outcome findings, missing-data methods, multiplicity handling, and the trial’s sample-size justification are not reported in the registry record in the registry record for this analysis.