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 Time-motion Study Comparing Self- to Nurse-vaccination With Influenza Vaccine (NCT01665807), a randomized phase 4 study. The primary outcome is Time to Administer Influenza Vaccine (in Seconds).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01665807 |
| Phase | Phase 4 |
| Condition | Influenza, Vaccination Site Reactions (HT) |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 868 |
| Arms in the primary outcome | 3 |
| Lead sponsor | Brenda Coleman |
| Results posted | Yes |
2. Clinical Question
Population
Health care workers in small-group settings were the focus of this time-motion study. The registry describes the intended setting as an acute care hospital. It records an enrollment of 868, while the primary endpoint results list participant counts separately for each arm. Further eligibility criteria and the analysis population are not reported in the registry record.
Intervention
One group self-administered intradermal influenza vaccine, Intanza, at a dose of 0.1 mL. A separate group self-administered Intanza after having self-administered an intradermal vaccine in the 2010 study. The record distinguishes participants with this prior experience from the self-administration group without that description.
Comparator
The nurse-administered group received intramuscular influenza vaccine, Vaxigrip, at a dose of 0.5 mL. The registry identifies the study as randomized and parallel, but details of sequence generation, allocation concealment, and assignment among the listed arms are not reported in the registry record.
Primary question
The primary question was how much time was required to explain vaccination, obtain consent, administer the vaccine, and register the vaccination on Day 0. The investigators hypothesized that self-administration of the intradermal vaccine would take less time than nurse administration of the intramuscular vaccine, and that prior self-administration experience would be associated with less time than first-time self-administration.
This is a question about the time required for a defined vaccination process, not only the time spent delivering the injection. The endpoint includes explanation, consent, administration, and registration, so the recorded duration reflects the whole specified workflow. Results describe the groups as recorded; they do not by themselves establish why any difference in time occurred.
3. Trial Design
NCT01665807 is a completed, Phase 4, randomized, unmasked, parallel study. The registry lists a start date of 2012-09 and a primary completion date of 2012-12. Its title identifies it as a time-motion comparison of self- and nurse-vaccination with influenza vaccine. The registry records enrollment of 868.
The listed arms differ in both delivery method and, for the repeat self-administration group, prior experience. The nurse-administered intramuscular arm used Vaxigrip at 0.5 mL. The self-administered intradermal arm used Intanza at 0.1 mL. The repeat self-administration intradermal arm also used Intanza at 0.1 mL, and is described as including participants who self-administered an intradermal vaccine in the 2010 study. The primary endpoint results list 408 participants in the nurse-administered arm, 395 in the self-administered arm, and 57 in the repeat self-administration arm.
Randomization is recorded, but the registry does not report the sequence-generation method, concealment procedures, stratification, or the precise allocation process. It also does not explain how the repeat self-administration group was incorporated into randomization or whether its prior experience affected eligibility or assignment. Masking is listed as none; who knew the assigned procedure and whether outcome recording was otherwise standardized are not reported in the registry record.
The registry lists acceptability, success rate, local and systemic reactogenicity, and pain at the injection site as secondary outcomes. It records no analysis entries. The record does not provide a detailed statistical analysis plan, protocol rationale for the group sizes, or an explanation for the participant counts used for each outcome.
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: People who had self-administered intradermal influenza vaccine in past were only eligible for the "repeat" self-administration arm. No other pre-assignment eligibility criteria.
Overall Study
| Stage | Nurse-administered IM | Repeat Self-administration Intradermal | Self-administered Intradermal |
|---|---|---|---|
| STARTED | 411 | 58 | 402 |
| COMPLETED | 409 | 58 | 401 |
| NOT COMPLETED | 2 | 0 | 1 |
Reasons for not completing this period:
| Reason | Nurse-administered IM | Repeat Self-administration Intradermal | Self-administered Intradermal |
|---|---|---|---|
| Withdrawal by Subject | 2 | 0 | 1 |
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 | Nurse-administered IM | Repeat Self-administered Intradermal | Self-administered Intradermal | Total |
|---|---|---|---|---|---|
| Participants analysed | 411 | 58 | 402 | 871 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 386 | 58 | 391 | 835 |
| Age, Categorical: >=65 years | Participants | 25 | 0 | 11 | 36 |
| Age, Continuous | years | 44.0 (SD 13.2) | 40.2 (SD 11.3) | 41.2 (SD 12.6) | 42.5 (SD 12.9) |
| Sex/Gender, Customized: Female | participants | 295 | 39 | 282 | 616 |
| Sex/Gender, Customized: Male | participants | 113 | 19 | 119 | 251 |
| Region of Enrollment: Canada | participants | 411 | 58 | 402 | 871 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Administer Influenza Vaccine (in Seconds), measured over Vaccination (Day 0).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | seconds |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is “Time to Administer Influenza Vaccine (in Seconds).” It is defined as the time required to explain vaccination, obtain consent, administer the vaccine, and register the vaccination. The timeframe is vaccination on Day 0. Because the endpoint includes several steps, it represents the duration of the specified vaccination process rather than injection time alone.
The registry reports the endpoint as a median with a full range. For the nurse-administered intramuscular arm, the median is 90.0 seconds, with a range from 18.0 to 235.3. For repeat self-administration, the median is 182.0 seconds, with a range from 42.5 to 671.1. For self-administered intradermal vaccination, the median is 62.6 seconds, with a range from 29.8 to 97.7.
A median describes the central position of the observed times without requiring the mean to represent a typical participant when values are unevenly distributed. The full range conveys the spread between the smallest and largest recorded values, but it does not show the distribution of observations between those endpoints. This measure is useful for describing workflow duration, but it does not alone identify which component of the process accounts for the observed times. The registry does not report confidence intervals or an inferential comparison for the primary endpoint, so the precision of differences between groups cannot be assessed from the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary results are descriptive medians and full ranges for the three listed arms. The median is 90.0 seconds in the nurse-administered intramuscular group, 62.6 seconds in the self-administered intradermal group, and 182.0 seconds in the repeat self-administration group. These values describe the recorded durations in each arm. The ranges are 18.0 to 235.3, 29.8 to 97.7, and 42.5 to 671.1 seconds, respectively. The ranges indicate that individual recorded times varied within each group; they do not provide a measure of uncertainty around the medians.
The ordering of the medians is consistent with the investigators’ stated hypothesis for self-administration without prior experience compared with nurse administration, but the registry does not report a formal statistical comparison or a confidence interval. A difference between observed medians is not, on its own, evidence that the population-level times differ. The precision of that comparison, and whether it is compatible with a range of plausible effects, cannot be evaluated from the reported primary endpoint information.
The repeat self-administration group has the largest reported median time. That descriptive result does not establish that prior experience makes self-administration slower. This group is defined by having self-administered an intradermal vaccine in the 2010 study, and the record does not explain how participants entered this group, how they were assigned relative to other arms, or whether other group characteristics differed. The stated hypothesis about second-time administration therefore cannot be assessed simply by treating the three medians as a controlled sequence of experience.
The primary endpoint sample counts are 408, 395, and 57 for the nurse-administered, self-administered, and repeat self-administration arms. The safety counts use different at-risk totals: 409, 401, and 58 for those corresponding groups. Reasons for the differences in counts are not reported in the registry record. The record gives overall enrollment as 868 but does not describe the endpoint-specific analysis populations or account for participants not represented in each result.
No p-value, confidence interval, adjusted estimate, or stated model for the primary endpoint is reported in the registry record. The record also lists no analysis entries. Consequently, the results support a descriptive account of recorded times, not a claim about statistical significance or a quantified causal effect. The practical meaning of the times depends on the workflow used in this study, including explanation, consent, administration, and registration, and should not be generalized to a different process without relevant evidence.
9. Statistical Methods Explained
The statistical information in the registry is limited. The primary endpoint is reported as a median and full range for each arm. No formal comparison, confidence interval, p-value, or model-based estimate is reported in the registry record. The interpretation should therefore distinguish the observed summaries from inferential conclusions about differences beyond the participants whose results are listed.
What does a median describe?
In general, a median is the central value of an ordered set of observations: half of the observations lie at or below it and half lie at or above it, subject to conventions for an even number of observations. Unlike a mean, it is less affected by extreme values. That can be useful for time measurements, which may include a small number of unusually long durations. Here, the registry identifies the median as the summary measure, but does not describe the underlying distribution or explain why this measure was selected.
A median is not a statement that every participant took approximately that amount of time. The reported full ranges make clear that the observed times span a wider interval in each arm. A range uses only the smallest and largest values; it does not reveal whether observations cluster near the median, occur unevenly across the interval, or include isolated extreme values. The record does not provide additional distribution summaries such as quartiles or individual observations.
What does a range show, and what does it leave out?
In general, the full range describes the endpoints of the observed data. It is not a confidence interval and does not quantify how precisely a median estimates a population value. Confidence intervals, when reported, describe uncertainty in an estimate under specified assumptions and a specified method. No confidence interval for the group medians or their contrasts is reported in the registry record. It is therefore not possible to use the listed ranges as a substitute for inferential uncertainty.
For the primary endpoint, the reported medians and ranges are descriptive summaries in seconds. They permit a reader to compare the observed central times and observed spans across arms, but do not establish whether an apparent difference is distinguishable from sampling variability. The registry does not report the statistical test or estimation procedure that would be needed to make that assessment.
Why does the design matter?
In general, randomization can support a causal comparison by balancing measured and unmeasured characteristics on average, provided assignment is implemented as intended and the analysis preserves the randomized comparison. This record labels the study randomized and parallel, but does not give the assignment method or explain the handling of the repeat self-administration group. The latter group is described through prior participation in the 2010 study, so experience status is part of how that arm is defined. Without details of recruitment and allocation for this group, its median should be read as a descriptive result rather than an isolated estimate of the effect of experience.
The study is unmasked. For a time-motion endpoint, awareness of the procedure could potentially influence behavior or timing, but the record does not describe who recorded times, how timing was standardized, or whether assessors could influence the measured process. This is a general consideration for unmasked measurement; the registry does not establish that such influence occurred.
What do the planning illustrations represent?
In general, a sample-size calculation estimates how many participants might be needed to detect a specified effect under stated assumptions. The planning approach associated with these results is described as an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The target effect is expressed as a stated fraction of the observed effect. These planning illustrations are not the trial’s own design justification and are not observed power. The registry record does not report the trial’s sample-size justification or establish that the trial was planned around the observed result.
In general, observed power is not a substitute for an uncertainty interval: calculations based on an observed effect can give a misleading impression of how informative a completed study is. Planning calculations are most useful when their target effect and assumptions are chosen before outcomes are known. No numerical planning estimates or target fractions are reported in the registry record described for this study, so no specific required sample size can be interpreted.
Why can no comparison be recovered from the summaries alone?
A formal comparison needs an estimand and a method that account for the endpoint, the randomized groups, and any relevant features of the design. The posted results provide separate medians and ranges but no reported contrast, standard error, confidence interval, or test. It would not be appropriate to infer a p-value or uncertainty interval by treating the ranges as if they were standard errors. The registry’s analysis count is 0, and it states that values are missing or not estimable for a two-arm comparison for this other endpoint. Thus, the descriptive summaries are the available basis for interpretation, while comparative statistical precision remains unreported.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists secondary outcomes of acceptability of vaccine, success rate, local and systemic reactogenicity, and pain at the injection site. It does not report estimates or analyses for these outcomes in the information available for interpretation. A statistical analysis plan describing which outcomes were primary or secondary for testing, the order of hypotheses, or any adjustment for multiple comparisons is not reported in the registry record.
In general, when several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase if each is assessed separately without accounting for multiplicity. This is a general statistical issue, not evidence that a particular adjustment was required or used in this study. The record does not permit assessment of whether multiplicity was addressed in a protocol or analysis outside the registry.
Missing-data handling and analysis populations are also not described. The primary endpoint counts are 408 for nurse administration, 395 for self-administration, and 57 for repeat self-administration. The corresponding safety at-risk counts are 409, 401, and 58. The reasons for these differences, and whether any outcome values were missing, excluded, or not estimable, are not reported in the registry record. Enrollment is listed as 868, but the record does not provide a participant flow account linking enrollment, allocation, follow-up, and each endpoint’s analysis set.
The registry identifies the study as randomized, but does not state whether the primary analysis followed intention-to-treat principles, used a per-protocol population, or applied another approach. It also does not describe imputation, sensitivity analyses, exclusions, or handling of protocol deviations. These omissions limit the ability to judge how representative the posted endpoint summaries are of all enrolled or randomized participants.
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 |
|---|---|---|---|
| Nurse-administered IM | 0 | 409 | 0.0% |
| Repeat Self-administration Intradermal | 0 | 58 | 0.0% |
| Self-administered Intradermal | 0 | 401 | 0.0% |
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 |
|---|---|
| Nurse-administered IM | 0 of 409 |
| Repeat Self-administration Intradermal | 0 of 58 |
| Self-administered Intradermal | 0 of 401 |
The registry reports zero serious adverse events among the participants listed as at risk in each arm: 409 in the nurse-administered intramuscular group, 58 in the repeat self-administration intradermal group, and 401 in the self-administered intradermal group. It also reports zero other adverse events in each of those groups. These are the recorded affected counts and at-risk totals; they are not estimates of the probability of an event outside the reported study groups.
The serious-event and other-event counts should be read as separate registry categories. The record does not provide serious-event terms, and no top serious-event terms are listed. Death counts are not reported in the registry record. The adverse-event timeframe, collection procedures, event definitions, and completeness of ascertainment are not described in the information, so the zero affected counts should not be interpreted as proof that no event could occur.
The safety at-risk totals differ from the primary endpoint participant counts. The reason for this is not reported in the registry record. The safety figures describe the registry’s listed event counts; they do not answer the time-to-administer question and should not be used to infer comparative safety beyond those reported counts.
12. What the Result Does, and Does Not, Mean
The primary endpoint results describe how long the defined vaccination process took in each listed arm. The median recorded time was 90.0 seconds with nurse-administered intramuscular vaccination, 62.6 seconds with self-administered intradermal vaccination, and 182.0 seconds with repeat self-administration. These are observed group summaries, with full ranges indicating variation among recorded times.
The results do not establish a statistically supported difference between procedures. No inferential comparison or confidence interval is reported in the registry record, and the available descriptive summaries do not quantify uncertainty around the medians or contrasts. The record therefore cannot establish how precisely the observed ordering reflects a broader population comparison.
The results also do not isolate the contribution of the injection procedure from the other measured tasks. The endpoint includes explaining vaccination, obtaining consent, administering vaccine, and registering vaccination. Without component-level times, the data cannot show which part of the workflow accounts for a group’s overall duration. The registry does not report additional details about staff roles, timing procedures, or the operational setting beyond the small-group health care worker context.
The repeat self-administration result does not by itself quantify an effect of practice. The arm is described as participants with prior intradermal self-administration in the 2010 study. Recruitment and allocation details for this group are not reported, so differences between it and the other arms may not be attributable to experience alone.
More generally, the record does not provide a basis for claims about vaccination success, acceptability, reactogenicity, pain, or outcomes beyond the measures it reports. Those outcomes are listed as secondary outcomes, but their analysis results are not reported in the registry record. The listed adverse-event counts are limited to the recorded affected and at-risk totals and do not replace detailed information on ascertainment or follow-up.
13. Why This Trial Matters Statistically
This study illustrates why the definition of a time endpoint matters. A duration can describe more than the central act of administration: here it includes explanation, consent, administration, and registration. That definition makes the endpoint relevant to the specified workflow, while also limiting its interpretation to that workflow. A shorter overall duration would not identify which task changed or why.
The results also show the distinction between descriptive summaries and statistical evidence for a comparison. Medians and ranges communicate central observed times and their observed spans. They do not quantify the uncertainty of a contrast. Without a reported inferential analysis or confidence interval, readers cannot determine the precision of comparative estimates or judge how compatible the data are with different possible population effects.
The prior-experience group raises a design question that is important in time-motion studies. A group defined by previous self-administration is not simply another delivery procedure: it also represents a different experience history. The registry gives the history as having self-administered intradermal vaccine in the 2010 study, but does not explain how that group was recruited or allocated. That detail matters when interpreting a difference as an experience effect rather than a descriptive difference between groups.
Finally, reporting outcome-specific counts and analysis details is important for assessing what the results represent. The primary endpoint and safety summaries use different participant counts, while the registry does not explain the analysis populations or missing-data approach. The record’s randomized, unmasked, parallel design provides useful context, but without fuller methods and comparative estimates, the posted results remain descriptive. This is a useful example of how a registry can convey the direction and spread of observed data while leaving key questions about precision, group comparability, and analysis unresolved.
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 main limitation for statistical interpretation is the absence of a reported inferential analysis for the primary endpoint. The record gives medians and full ranges but no confidence intervals, p-values, or adjusted comparisons. The observed summaries therefore do not establish the precision or statistical significance of differences among arms.
The registry labels the study randomized and parallel, but does not describe sequence generation, concealment, allocation procedures, or the treatment of the repeat self-administration arm in the randomization process. That arm is defined by prior self-administration in the 2010 study. The record does not describe how those participants were recruited or how their allocation related to the other groups, limiting interpretation of the comparison as an effect of prior experience.
The study is unmasked, and the record does not explain who measured the times, how timing was standardized, or whether the recording process was independent of the vaccination procedure. Because the endpoint includes several workflow activities, the lack of component-level times also limits interpretation of what produced the observed duration.
Counts differ between the primary endpoint and adverse-event summaries, and the reason is not reported in the registry record. Participant flow, outcome-specific analysis populations, missing-data handling, exclusions, and protocol deviations are not described. The record also does not report the sample-size justification or a detailed statistical analysis plan, including multiplicity procedures for the listed secondary outcomes.
Finally, the registry lists secondary outcomes but does not provide their analysis results in the information reported for this study. Safety counts lack reported event definitions, ascertainment details, and timeframe, while death counts are not reported in the registry record. These limitations do not alter the descriptive values; they constrain how broadly or causally those values can be interpreted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Time-motion Study Comparing Self- to Nurse-vaccination With Influenza Vaccine — NCT01665807.
- Registry record last updated 2017-04-19; status last verified 2017-03.
- Results first posted 2013-10-01.
- 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
NCT01665807, “A Time-motion Study Comparing Self- to Nurse-vaccination With Influenza Vaccine,” is a completed, Phase 4, randomized, unmasked, parallel study. The registry records enrollment of 868 and dates of 2012-09 to 2012-12. It compares nurse-administered intramuscular Vaxigrip, self-administered intradermal Intanza, and repeat self-administration by participants with prior experience in the 2010 study.
The primary endpoint is time in seconds for explanation, consent, vaccination, and registration on Day 0. The posted medians are 90.0 seconds for nurse administration, 62.6 seconds for self-administration, and 182.0 seconds for repeat self-administration. The registry does not report a formal comparison or confidence interval for these results.
Acceptability, success rate, local and systemic reactogenicity, and injection-site pain are listed as secondary outcomes. Adverse-event affected counts are zero in the listed groups; death counts are not reported in the registry record. Analysis methods, missing-data handling, and the sample-size justification are not reported in the registry record.