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 Safety and Reactogenicity of GlaxoSmithKline (GSK) Biologicals' IPV Vaccine (PoliorixTM) in Toddlers (NCT00920439), a na phase 3 study. The primary outcome is Number of Subjects With Any and Grade 3 Solicited Local Symptoms.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00920439 |
| Phase | Phase 3 |
| Condition | Poliomyelitis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 26 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned healthy male or female toddlers in China, aged 18-24 months inclusive. The primary endpoint’s analysis population was the Total Vaccinated Cohort, defined as subjects with documented administration of the study vaccine. The registry record reports enrollment of 26, but does not report the size of that primary analysis population.
Intervention
Participants received a single booster dose of Poliorix, an inactivated poliomyelitis vaccine. The registry record says it was administered by intramuscular injection into the upper right thigh. The study was open-label, so masking was none.
Comparator
There was no concurrent comparison group in this single-group study. Allocation is listed as not applicable. Consequently, the study does not provide a randomized or controlled estimate comparing Poliorix with another vaccine, placebo, or no booster.
Primary question
The primary endpoint counted subjects with any solicited local symptoms and with Grade 3 solicited local symptoms during the 4-day (Days 0-3) post-vaccination period. The solicited symptoms were pain, redness, and swelling. The endpoint is framed as a safety and reactogenicity assessment after vaccination, rather than a test of comparative effectiveness. Numerical primary-endpoint results are not reported in the registry record, so the frequency of these symptoms cannot be described from this record.
3. Trial Design
This was a Phase 3, open-label, single-group study of Poliorix in healthy toddlers in China. The registry record gives enrollment as 26 and lists the study status as completed. Its recorded start date is 2009-06-01 and its primary completion date is 2009-08-03. The intervention was a single booster dose administered intramuscularly into the upper right thigh. There was no masking and no randomized allocation; the registry lists the allocation as not applicable.
The design is suited to describing observations after vaccination in the enrolled group. It does not create a contemporaneous control group for separating symptoms associated with vaccination from symptoms that might have occurred in the absence of vaccination. Nor does it support a randomized comparison between alternative products or schedules. Those limits matter when interpreting safety counts: counts in a single group describe what was recorded among participants at risk, but do not establish comparative excess risk.
The study’s stated focus was safety and reactogenicity. The primary endpoint concerns solicited local symptoms during the 4-day (Days 0-3) period after vaccination. The endpoint description defines any symptom as all reports irrespective of intensity grade. It defines Grade 3 pain as crying when the limb was moved or pain occurring spontaneously, and Grade 3 redness or swelling as spreading beyond 30 millimeters from the injection site.
The registry record lists four outcome measures and zero analysis records. The numerical results for the primary symptom endpoint, details of any statistical analysis plan, and the rationale for the planned enrollment are not reported in the registry record. Enrollment and the safety denominators should not be assumed to be the same: the record reports 26 enrolled, while the adverse-event figures use 25 subjects at risk. The reason for that denominator difference is not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Poliorix Group |
|---|---|
| STARTED | 25 |
| COMPLETED | 25 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The analysis was performed on the Total Vaccinated Cohort, which included all subjects with documented administration of the study vaccine.
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 | Poliorix Group |
|---|---|---|
| Participants analysed | 25 | |
| Age, Continuous | Months | 20.3 (SD 1.49) |
| Sex: Female, Male: Female | Participants | 13 |
| Sex: Female, Male: Male | Participants | 12 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Subjects With Any and Grade 3 Solicited Local Symptoms, measured over During the 4-day (Days 0-3) post-vaccination period.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Subjects |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts subjects with solicited local symptoms, considering both any reported symptom and Grade 3 symptoms. The symptoms assessed were pain, redness, and swelling at the injection site, during the 4-day (Days 0-3) post-vaccination period. The record defines any symptom as a report regardless of intensity. It defines Grade 3 pain as crying when the limb was moved or pain that was spontaneous; Grade 3 redness or swelling meant spread beyond 30 millimeters from the injection site.
Counting subjects makes the outcome a binary participant-level measure: each subject either had a specified symptom or did not, for the relevant endpoint definition and observation period. Such measures are useful for describing how many participants experienced common, actively solicited reactions and how many experienced reactions meeting a more severe intensity definition. Solicitation also makes the assessment focused on named symptoms rather than relying only on unsolicited reporting.
These measures describe local reactogenicity, not vaccine effectiveness. The open-label, single-group design also means the endpoint does not compare symptom frequency against an unvaccinated or alternative-vaccine group. Although the registry record describes the endpoint and the Total Vaccinated Cohort, it does not report the primary endpoint’s numerical counts or percentages. The observed frequency therefore cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study context and endpoint definitions, but it does not give the numerical primary-endpoint results. In particular, it does not report how many subjects had any pain, redness, or swelling, or how many had Grade 3 symptoms. The direction and size of the observed symptom frequencies therefore cannot be characterized from this record. The absence of those numbers is not evidence that no symptoms occurred.
The study enrolled 26 participants and used a single Poliorix group. Its adverse-event summary gives 25 subjects at risk for serious adverse events and zero subjects affected; it also reports 25 at risk for other adverse events and 14 affected. Deaths are reported as zero. These figures are descriptive safety counts in the listed group. They are not comparative estimates, because no control group was included.
For interpretation, a count should be read together with its denominator, event definition, observation period, and analysis population. The serious adverse-event figures have a denominator of 25, whereas the registry’s enrollment figure is 26. The reason they differ is not reported in the registry record. The record separately defines the primary endpoint population as subjects with documented vaccine administration, but does not state its size. These distinctions prevent assuming that every reported denominator refers to the same set of participants.
Statistical precision cannot be judged for the primary symptom outcomes because their event counts and uncertainty estimates are not reported in the registry record. The registry also lists zero analysis records, so no primary-endpoint estimate, confidence interval, or hypothesis test is available in the record. General statistical interpretation: a confidence interval describes the uncertainty around an estimated quantity, while a point estimate alone does not show how precisely that quantity is known. Neither can be interpreted without the relevant outcome data.
The record’s status is completed, but completion does not fill in the missing numerical endpoint results. The available safety summary can support only the limited statement that zero serious adverse events and zero deaths were reported among the 25 subjects listed at risk, and that 14 of the 25 listed at risk for other adverse events were affected. It cannot establish comparative safety or resolve the unreported solicited-symptom frequencies.
9. Statistical Methods Explained
The registry record describes a single-group study and lists zero analysis records. It gives endpoint definitions and some adverse-event counts, but no inferential analysis for the primary symptom outcome. The concepts below explain how such outcomes are generally interpreted; they should not be mistaken for methods documented as used in this study.
What does a participant count represent?
For a binary endpoint, each participant is classified according to whether the defined event occurred during the specified observation period. A count of participants with an event is usually interpreted alongside the number of participants assessed. The ratio of those quantities can be expressed as a proportion or percentage, but the primary symptom counts needed to describe those quantities are not reported in the registry record. No symptom percentages should therefore be inferred from the available information.
The registry’s primary endpoint refers to subjects with any and Grade 3 solicited local symptoms. “Any” includes reports irrespective of intensity grade, while Grade 3 uses the symptom-specific definitions in the record. These are distinct ways to summarize the observations. A participant meeting a Grade 3 definition would also have a symptom report, but the record does not provide counts that would allow the overlap or the separate frequencies to be described.
Why does the observation period matter?
An endpoint is defined not only by what counts as an event, but also by when events are counted. The primary symptom window is the 4-day (Days 0-3) post-vaccination period. That makes the endpoint a description of symptoms observed during that stated window, rather than a summary of all possible later experiences. The record does not report the primary endpoint results or additional detail about how missing symptom observations, if any, were handled.
What would uncertainty estimates add?
General statistical explanation: a point estimate describes the observed sample, while a confidence interval communicates uncertainty about the underlying quantity under the assumptions of the analysis. In a single-group binary outcome, an interval around a proportion can help show how much uncertainty remains when the sample is limited. A confidence interval is not a guarantee that the true value lies within its limits, and it does not remove design limitations such as the absence of a comparator.
No confidence interval for the primary endpoint is reported in the registry record. No p-value or other primary-endpoint test is reported either. With no reported symptom event counts, neither the observed proportion nor its precision can be reconstructed. The zero analysis records listed in the registry are consistent with the absence of a posted analysis record, but do not establish which methods may have been used outside the registry.
Why does the single-group design affect inference?
General statistical explanation: a controlled comparison can estimate a contrast between groups, whereas a single-group study describes outcomes in one group. Without a concurrent control, symptom counts after vaccination cannot by themselves distinguish symptoms attributable to the intervention from background events or other influences. Open-label assessment can also affect reporting or assessment of subjective symptoms. These are design considerations, not evidence that reporting was biased in this study.
Because there is no between-group contrast, comparative measures such as a risk difference or relative risk are not available from this design. The registry record lists allocation as not applicable and describes a single group. Any interpretation should therefore remain descriptive and should not be phrased as a randomized comparison.
What do the safety counts show?
The adverse-event summary distinguishes serious adverse events, other adverse events, and deaths. It reports zero subjects affected by a serious adverse event among 25 at risk, 14 affected by other adverse events among 25 at risk, and zero deaths. These categories should not be conflated: the other-adverse-event count is not a count of serious events. The registry does not list top serious-event terms, so the record does not identify particular serious-event diagnoses.
General statistical explanation: a zero observed count is an observation in the monitored group, not proof that the underlying event probability is zero. Precision depends on the denominator and on the event ascertainment and follow-up. A single-group count also cannot provide a comparative estimate. The adverse-event figures should therefore be reported as observed counts with their stated denominators, without converting them into a claim of no risk.
How should planning calculations be distinguished from results?
General statistical explanation: sample-size planning asks how many participants might be needed to detect an assumed effect under specified design and analysis assumptions. Such a calculation is not an observed outcome and is not a retrospective measure of the trial’s success. The registry record does not report a sample-size justification or a trial-specific statistical plan. Any planning illustration based on an observed effect would not replace those missing design details or constitute observed power.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures, but the numerical result details for the primary symptom endpoint are not reported in the registry record. The record does not explain how the outcomes were prioritized analytically beyond identifying the primary endpoint, nor does it report whether multiple testing was addressed. A multiplicity procedure, if any, is not reported in the registry record. Without the endpoint results and analysis details, it is not possible to determine how multiple outcomes were handled or how that might affect inferential claims.
The primary analysis population is described as the Total Vaccinated Cohort, including subjects with documented administration of the study vaccine. Its size is not reported in the registry record. Enrollment is 26, while the adverse-event summary lists 25 at risk for each of its event categories. The reason for the difference is not reported, and the adverse-event denominators should not be treated as the primary endpoint denominator without evidence that they match.
Missing symptom observations, exclusions, withdrawals, and imputation methods are not reported in the registry record. It is therefore not possible to assess whether all enrolled or vaccinated subjects contributed to every endpoint, whether any observations were incomplete, or how incomplete records were treated. These details matter because analysis populations and missing-data methods can affect the interpretation of a participant-level event frequency.
The record lists zero analysis records. It does not report a statistical analysis plan, interim analyses, or a sample-size justification. Those details should not be inferred from the study’s Phase 3 designation, enrollment, or completed status. The available record supports a description of the stated design and reported safety counts, but not a reconstruction of the unreported analysis process.
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 |
|---|---|---|---|
| Poliorix Group | 0 | 25 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Poliorix Group | 0 of 25 |
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 |
|---|---|
| Poliorix Group | 14 of 25 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Poliorix Group |
|---|---|---|
| Pyrexia | General disorders | 7 of 25 |
| Erythema | Skin and subcutaneous tissue disorders | 5 of 25 |
| Irritability | Psychiatric disorders | 5 of 25 |
| Pain | General disorders | 4 of 25 |
| Decreased appetite | Metabolism and nutrition disorders | 3 of 25 |
| Nasopharyngitis | Infections and infestations | 3 of 25 |
| Somnolence | Nervous system disorders | 3 of 25 |
| Swelling | General disorders | 3 of 25 |
| Upper respiratory tract infection | Infections and infestations | 3 of 25 |
The adverse-event summary reports zero subjects with a serious adverse event among 25 subjects at risk, 14 subjects with other adverse events among 25 at risk, and zero deaths. These are counts for the Poliorix group. The registry does not list top serious-event terms, so it does not identify any specific serious-event diagnosis in the posted summary.
Serious adverse events and other adverse events are separate categories in the record. The count of 14 applies to other adverse events; it should not be read as a count of serious events. The record’s zero serious-event count means no affected subjects are reported in that category for the stated group and denominator. It does not establish that the underlying risk is zero or that no events could occur in a larger or differently followed population.
The adverse-event denominator is 25, while enrollment is 26. The reason for this difference is not reported in the registry record. The record does not give further detail about the safety observation period or the event terms within the other-adverse-event category. As a result, the counts are best read as limited descriptive information, not as a complete account of all event types, timing, or comparative safety.
12. What the Result Does, and Does Not, Mean
The record documents an open-label, single-group study of a single Poliorix booster dose in healthy toddlers aged 18-24 months in China. It specifies a primary endpoint covering solicited local symptoms during the 4-day (Days 0-3) post-vaccination period and defines the symptom and Grade 3 categories. It also reports selected adverse-event counts for the Poliorix group.
What the record does not establish is the numerical frequency of the primary local symptoms. Those counts are not reported in the registry record. It therefore cannot show from the posted primary endpoint whether any symptom was common or uncommon, or how frequently Grade 3 symptoms occurred. The absence of reported primary results should not be mistaken for a finding of zero symptoms.
The study also cannot estimate a causal contrast against another intervention or against no booster. There was no control group, and allocation is listed as not applicable. The event counts describe the group studied; they do not show what would have happened to comparable toddlers under a different condition. Open-label assessment is another feature to consider when interpreting solicited symptoms, particularly because the record does not describe masking.
The safety summary is narrower and does report zero subjects with serious adverse events and zero deaths among 25 listed at risk, alongside 14 subjects with other adverse events among 25 at risk. These are observed counts, not proof of absence of risk. The record does not provide the serious-event terms or additional detail needed to characterize the other events.
Overall, the registry record supports a clear description of the design, endpoint definitions, and selected safety counts, but the missing primary symptom results and lack of a comparator sharply limit further statistical interpretation. The reported enrollment and completed status do not substitute for outcome estimates or uncertainty measures.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of the difference between describing an outcome and comparing outcomes. A single-group safety study can record symptoms after vaccination, but without a concurrent comparator it cannot estimate how those observations differ from another group’s experience. That distinction remains important even when a trial has a formal phase designation and a defined primary endpoint.
The endpoint definitions are also central to interpretation. The record distinguishes any solicited local symptom from Grade 3 symptoms and specifies a post-vaccination observation window. A transparent definition helps readers understand what is counted, but definitions alone are not results. The primary symptom counts are not reported in the registry record, so the endpoint cannot be quantitatively interpreted from the available entry.
The record further illustrates why denominators and populations must be stated precisely. Enrollment is 26, the safety summary uses 25 subjects at risk, and the size of the Total Vaccinated Cohort is not reported. Those quantities may refer to different analytic contexts; the record does not explain the difference. Avoiding assumptions about their equivalence is essential to accurate reporting.
Finally, safety counts need cautious language. Zero serious adverse events and zero deaths are the reported observations for the stated denominator, not proof that risk is absent. The 14 subjects with other adverse events should remain distinct from the serious-event category. These statistical distinctions help prevent descriptive evidence from being overstated as comparative or definitive evidence.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The primary limitation for interpretation is that numerical results for the primary symptom endpoint are not reported in the registry record. Without counts for any or Grade 3 local symptoms, readers cannot assess their observed frequency or precision. The record gives endpoint definitions, but not the corresponding results.
The study has a single group, no randomized allocation, and no masking. It therefore offers no randomized comparator and cannot estimate a comparative effect. The open-label design may be relevant when interpreting solicited symptoms, but the record does not report whether or how symptom assessment could have been influenced by knowledge of vaccination.
Although enrollment is 26, the adverse-event summary lists 25 subjects at risk, and the size of the primary Total Vaccinated Cohort is not stated. The reason for the denominator difference is not reported in the registry record. Missing outcomes, withdrawals, exclusions, and the handling of incomplete observations are also not reported, limiting assessment of analysis-population completeness.
The record lists four outcome measures and zero analysis records. A statistical analysis plan, multiplicity handling, interim analyses, and sample-size justification are not reported in the registry record. The adverse-event summary does not list top serious-event terms and gives limited detail about event types and observation duration. These gaps constrain the ability to assess completeness, precision, and the broader safety profile from this record alone.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Reactogenicity of GlaxoSmithKline (GSK) Biologicals' IPV Vaccine (PoliorixTM) in Toddlers — NCT00920439.
- Registry record last updated 2018-01-19; status last verified 2017-05.
- Results first posted 2017-10-19.
- 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
NCT00920439 is a completed Phase 3, open-label, single-group study sponsored by GlaxoSmithKline. It enrolled 26 healthy toddlers in China and evaluated a single intramuscular booster dose of Poliorix in participants aged 18-24 months. The recorded study start was 2009-06-01, and primary completion was 2009-08-03.
The primary endpoint counted subjects with any and Grade 3 solicited local symptoms during the 4-day (Days 0-3) post-vaccination period. Numerical results for that endpoint are not reported in the registry record. The safety summary reports zero serious adverse events and zero deaths among 25 subjects at risk, and 14 subjects with other adverse events among 25 at risk. There was no comparator, and the record lists zero analysis records.