Influenza Vaccination for Parents and Other Caregivers in the Pediatric Medical Home: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Influenza Vaccination for Parents and Other Caregivers in the Pediatric Medical Home (NCT00812110), a na phase 4 study. The primary outcome is Number of Participants Who Received Influenza Vaccine..

2. Clinical Question

3. Trial Design

This completed study is registered as a phase 4, single-group intervention study of influenza vaccination for parents and other caregivers in the pediatric medical home. The sponsor is Akron Children's Hospital. The registry lists Influenza as the condition and influenza vaccine as the intervention. Enrollment is recorded as 336. The study start is listed as 2008-12, and primary completion as 2009-09.

The design is not randomized: allocation is recorded as NA, and the registry explicitly characterizes the study as not a randomized comparison. It also lists masking as none. With one group and no stated control arm, the main endpoint is descriptive: it records the number of caregivers who accepted an offered vaccine. There is no like-for-like control comparison from which to estimate a relative effect of the offer or to separate the offer from other influences on acceptance.

The primary outcome has a timeframe of 1 hour. Its description states that caregivers identified for participation were offered influenza vaccine, and that the outcome describes the number who accepted. The registry records two outcome measures, including a secondary outcome concerning the background rate of influenza vaccination among parents or caregivers of high-risk pediatric patients in a low-income population. The secondary outcome result is not reported in the registry record.

The registry status is completed, but completion status does not itself supply the numerical primary result or a statistical analysis. The record lists zero analyses. Details such as the recruitment process, the exact eligibility criteria, how the offer was delivered, and the planned handling of outcome data are not reported in the registry record. The registry summary describes a hypothesis that acceptance might approach rates seen in a neonatal intensive care unit environment; this is a stated expectation, not a posted study result.

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

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 Number of Participants Who Received Influenza Vaccine., measured over 1 hour.

The primary endpoint is the number of participants who received influenza vaccine. The registry describes the event more specifically as acceptance of the vaccine offer by caregivers identified for participation. Its timeframe is 1 hour. This is a count of participants meeting the endpoint, rather than a measure of vaccine effectiveness, duration of protection, or a comparison between treatment groups.

A count can directly describe how many people accepted in the study, but interpreting it as an acceptance rate also requires a clear denominator: the number of eligible or offered caregivers included in that calculation. The registry record gives enrollment as 336, while the adverse-event information uses a caregiver group at risk of 292. It does not state which, if either, is the denominator for the primary endpoint. These counts should not be substituted for one another or used to construct an acceptance rate without a defined analysis population and the primary outcome numerator.

Acceptance is a useful descriptive endpoint for a study asking whether caregivers accept an offer in a particular care setting. It represents the immediate response to the offer within the recorded timeframe. It does not, by itself, establish reasons for acceptance, persistence of vaccination behavior, or effects on influenza illness. The primary result is not reported in the registry record, so the endpoint’s observed count and precision cannot be assessed from the recorded results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study with a participant-count primary endpoint. Statistical interpretation therefore begins with the distinction between describing an observed count and estimating an acceptance rate. A count states how many participants met an endpoint. A rate additionally needs a defined population at risk or denominator. The primary outcome description gives the event and the 1-hour timeframe, but the registry record does not report the observed count or specify the primary analysis denominator.

What does a single-group design estimate?

In general, a single-group study can describe outcomes among the people who received or were offered an intervention, according to the study’s defined outcome and analysis population. If an outcome count and denominator are available, the corresponding proportion can describe the frequency of the event in that group. It remains a group-specific description. Without a comparison group, it does not estimate how the same population would have responded under a different approach.

This distinction matters for the caregiver vaccination question. Acceptance following an offer is an observable response, but a single-group result cannot by itself determine how much of that response is attributable to the offer, the setting, the way the offer was framed, vaccine access, or other factors. The registry does not report a randomized comparison, and it does not identify a comparator arm. The record therefore supports no between-group treatment-effect calculation.

Why does the endpoint’s scale matter?

The primary outcome is expressed as a number of participants who received vaccine. This is a count of events, not a continuous measurement such as a laboratory value. In general, a count can be modeled using methods suited to event counts, or it can be summarized descriptively. If the scientific question concerns the chance of acceptance among those offered vaccine, a proportion is often a natural summary, but the denominator and the rules for determining who belongs in that analysis must be clear.

In some count settings, the variability is greater than a simple model would expect. This is called over-dispersion. In general, accounting for over-dispersion can prevent uncertainty from being understated when a count model’s assumptions do not fit the observed data. That issue cannot be assessed from the registry information because the primary outcome count and its distribution are not reported. No model choice or count-model diagnostics are reported in the registry record.

What does uncertainty mean for a proportion?

In general, a confidence interval describes a range of values compatible with the observed data under a specified statistical procedure. A narrower interval indicates greater precision under that procedure, while a wider interval indicates more uncertainty. Precision depends not just on the event count, but also on the denominator, the design, and the method used. Since the primary outcome value, analysis denominator, and interval are not reported, the precision of the acceptance estimate cannot be evaluated.

A confidence interval is not a guarantee that the true value lies within a particular calculated range. It is a tool for showing sampling uncertainty under the assumptions of the analysis. Nor does an interval repair a design limitation: a precise description of a single group would still not provide a randomized comparison with an alternative strategy.

What can a hypothesis test establish?

In general, a hypothesis test evaluates how compatible the observed data are with a specified null hypothesis, given its assumptions. A p-value is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. Interpretation requires knowing the comparison, outcome, analysis population, and statistical procedure. The registry lists zero analyses, and no test statistic or p-value is reported in the registry record. No inferential conclusion should therefore be attributed to the study.

The stated 90-95% expectation appears in the registry summary as a hypothesis about possible vaccination rates. It is not accompanied in the record by a reported analysis comparing the observed endpoint with that expectation. Without an observed primary result and a defined analysis, there is no basis for judging whether the result was close to, below, or above that stated expectation.

How should planning calculations be distinguished from trial results?

In general, sample-size calculations describe how much information a proposed design might need under specified assumptions about an effect, variability, significance level, allocation, and analysis. They are planning illustrations, not observed evidence and not a measure of the study’s achieved power. A calculation based on an observed effect is especially dependent on that estimate and does not retroactively establish the design’s original justification.

The registry record does not report the trial’s sample-size justification or a statistical analysis plan. It also does not report a primary endpoint estimate from which to assess precision. Any planning illustration associated with this study should be read only as a hypothetical calculation under its stated assumptions, not as a result of the trial or as evidence that the trial had a particular probability of detecting an effect.

Finally, an outcome count and a safety count answer different questions. The primary count concerns vaccine acceptance. The adverse-event fields describe recorded events in a caregiver group. Neither set of counts can substitute for the other, and the safety denominator should not automatically be treated as the primary analysis denominator. General statistical interpretation depends on matching each estimate to its outcome definition, timeframe, population, and analysis method.

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("Caregivers")
n      <- c(292)
events <- c(250)
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  Caregivers  292  250  85.6  81.1  89.4  81.1  89.2  81.1  89.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: the primary count of participants who received influenza vaccine and a secondary question about the background vaccination rate among parents or caregivers of high-risk pediatric patients in a low-income population. It lists zero analyses. The results of both outcomes are not reported in the registry record. The registry does not describe a statistical analysis plan, the intended hierarchy of outcomes, or whether formal tests were planned.

In general, when a study assesses multiple outcomes or makes multiple statistical comparisons, the chance of a chance-positive finding can increase if each result is treated as a separate confirmatory test. Methods for handling multiplicity depend on the research questions and prespecified analysis plan. Since analyses and their results are not listed, it is not possible to determine whether multiplicity adjustments were planned or used. It would be inappropriate to infer that a particular adjustment was necessary or applied.

The record does not report missing-data procedures, outcome completeness, exclusions from the primary endpoint, or an analysis population definition. It therefore does not establish whether every enrolled participant contributed primary outcome data, how caregivers with an unknown acceptance status were handled, or whether any imputation was performed. The enrollment figure of 336 does not, by itself, specify the denominator for the primary endpoint. The adverse-event at-risk count of 292 is reported for safety and should not be assumed to define the primary analysis population.

In general, missing data can affect interpretation when the probability of missingness is related to participant characteristics or outcome status. Appropriate assessment depends on knowing how much data are missing, why they are missing, and the analysis methods. Those details are not reported in the registry record. No conclusions about completeness, attrition, or the handling of missing primary outcome values can be drawn from the posted information.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event information lists caregivers as the group at risk. It records zero serious adverse events among 292 at risk and zero other adverse events among 292 at risk. These are the specific recorded counts. They describe what appears in the registry safety fields; they do not demonstrate that no events occurred outside the reported collection or establish that the vaccine has no risk.

Zero recorded events should be interpreted in relation to the population monitored, the observation period, event definitions, and the completeness of reporting. The registry record does not report the methods used to collect safety information, the criteria for classifying events, or whether follow-up was complete. The adverse-event timeframe is not reported in the registry record. No serious adverse-event terms are listed. The deaths field is not populated with a numeric value, so deaths are not reported in the registry record rather than recorded as zero.

The safety group’s at-risk count is not stated to be the primary endpoint denominator. It should not be combined with or substituted for enrollment when interpreting vaccine acceptance. These registry figures are descriptive and do not provide a comparison with an unvaccinated group or a different vaccination strategy.

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

The result the study set out to describe is whether caregivers accepted an offered influenza vaccine, recorded as the number of participants who received it within a 1-hour timeframe. The registry record identifies the endpoint and the completed study status, but it does not report the primary outcome count. As a result, the posted information cannot establish the observed level of acceptance or its statistical precision.

The summary’s 90-95% figure is a hypothesis, not a finding. It describes the expectation that vaccination rates might approach rates in a neonatal intensive care unit environment when vaccine is offered at little or no cost and linked to the risk of a child. No result is reported that would show whether this expectation was reached. The registry also does not provide a reported outcome for the secondary question about background vaccination rates.

Even if an acceptance count were available, the single-group design would support a descriptive account of the caregivers in the study, not a direct estimate of the effect of offering vaccine versus another approach. There is no randomized comparator, and allocation is listed as NA. Other influences on acceptance could not be separated through the design described in the record.

The safety information records zero serious adverse events and zero other adverse events among 292 caregivers at risk. These counts should be read as registry entries, not as proof of no risk. Details on safety monitoring and the reporting period are not reported in the registry record.

The study therefore documents a setting and a question of practical interest, but its available registry results do not answer the central quantitative question. It does not establish the number or proportion accepting vaccination, nor does it establish a comparative treatment effect, the reasons for acceptance, or the broader consequences of vaccination. Those conclusions would require outcome and analysis information not reported in the registry record.

14. Why This Trial Matters Statistically

Statistically, the study illustrates the difference between a clearly stated measurement question and a result that can be interpreted quantitatively. The endpoint is understandable: count caregivers who accepted the vaccine offer within the specified timeframe. But a count alone does not answer a rate question unless the relevant denominator is defined, and the registry record does not report the observed primary count or its analysis population.

The design also makes the inferential boundary clear. A single-group study can characterize what happened among the group studied, but it does not provide the counterfactual comparison needed to estimate what would have happened under a different offer or no offer. This matters even when the research question concerns an immediate, readily observed behavior. A descriptive acceptance result and a causal effect are different statistical quantities.

The record’s stated hypothesis makes the gap between expectation and evidence especially important. A hoped-for rate is not an observed rate, and it cannot be judged against the study outcome without the outcome result and a defined analysis. Statistical reporting needs to distinguish the motivating hypothesis from the data obtained.

The safety fields provide another useful lesson in interpretation: a zero event count is a recorded observation within a defined reporting system, not proof of zero underlying risk. Clear information about event definitions, observation time, and completeness is necessary to understand what such a count can support.

More generally, this record shows why outcome definitions, denominators, analysis populations, missing-data handling, and statistical methods need to accompany results. Those elements determine whether a count can be turned into a meaningful estimate and how much uncertainty surrounds it. Their absence limits the conclusions available from the registry, regardless of the practical importance of the question.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most consequential limitation for interpreting the posted results is that the primary outcome count is not reported in the registry record. The endpoint is described, but without its observed value there is no basis for stating how many caregivers accepted vaccination or estimating an acceptance rate. The primary analysis denominator is also not specified. Enrollment is recorded as 336, and the safety information lists 292 caregivers at risk, but the registry does not explain which population is relevant to the primary outcome.

The study is single group, allocation is listed as NA, and masking is listed as none. There is no randomized or contemporaneous comparator described. Any descriptive acceptance result would therefore apply to the observed group and would not isolate the effect of the vaccine offer from the setting or other influences. The record does not report detailed recruitment or eligibility methods, so the representativeness of the caregivers cannot be assessed.

The registry lists a secondary background-rate question but does not report its result. It also lists zero analyses and does not report a statistical analysis plan, confidence intervals, hypothesis tests, missing-data methods, or analysis populations. It is therefore not possible to assess precision, prespecification, outcome completeness, or how any missing responses were handled. A trial-specific sample-size justification is not reported in the registry record.

Safety interpretation is also limited. The adverse-event fields report zero serious and zero other events among 292 at risk, but the event definitions, collection procedures, and observation period are not reported. The deaths field does not contain a numeric result. These gaps prevent a fuller assessment of safety reporting and should not be replaced with assumptions about monitoring or follow-up.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Influenza Vaccination for Parents and Other Caregivers in the Pediatric Medical Home — NCT00812110.
• Registry record last updated 2013-01-23; status last verified 2012-12.
• Results first posted 2013-01-23.
• 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

This completed phase 4 study, sponsored by Akron Children's Hospital, concerns offering influenza vaccine to parents and other caregivers in a pediatric medical home. It is registered as a single-group study with allocation listed as NA and no masking. Enrollment is recorded as 336; the study start is listed as 2008-12 and primary completion as 2009-09.

The primary endpoint is the number of participants who received influenza vaccine, with a timeframe of 1 hour. The primary result is not reported in the registry record. A secondary outcome asks about background vaccination among parents or caregivers of high-risk pediatric patients in a low-income population; its result is also not reported. The registry lists zero analyses.

Safety information records zero serious adverse events and zero other adverse events among 292 caregivers at risk. The registry does not report the primary outcome denominator, analysis methods, missing-data handling, or detailed safety-monitoring methods. The record supports a description of the study question and design, but not a quantitative conclusion about vaccine acceptance or a comparison with an alternative approach.