Promoting Altruism to Enhance Vaccine Acceptance: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Promoting Altruism to Enhance Vaccine Acceptance (NCT04568590), a na na study. The primary outcome is Change in Vaccine Hesitancy Scores Pre- and Post-Intervention..

2. Clinical Question

3. Trial Design

This study, NCT04568590, is titled Promoting Altruism to Enhance Vaccine Acceptance. Its official title describes a cohort study intended to determine the effect of an educational intervention focused on herd immunity on vaccination uptake rates. Wake Forest University Health Sciences is listed as the sponsor. The condition is vaccine refusal, and the intervention is categorized as behavioral.

The registry identifies the design as single-group, with no allocation and no masking. The study status is completed. The registry lists enrollment as 510, with a start date of 2020-10-19 and primary completion on 2021-10-26. These design and enrollment details do not establish how many participants contributed data to each outcome; the primary outcome description separately lists N=73 before the intervention and N=68 after it.

Participants who consented and were deemed vaccine hesitant were to receive the educational intervention. The stated purpose was to examine whether increasing awareness of herd immunity benefits, particularly for the local pediatric oncology community, could improve vaccination uptake. The study also lists influenza vaccine uptake and a pre-intervention altruism scale as secondary outcomes. There are 6 outcome measures in the record.

Because the study has no randomized control group, its pre- and post-intervention comparison is not a like-for-like comparison between assigned groups. The design can describe score measurements around the intervention among participants with available assessments, but it does not by itself establish that any observed change was caused by the intervention. The registry record does not report further details of recruitment, intervention delivery, or a statistical analysis plan.

4. Participant Flow and Accounting

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

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Population who scored as vaccine hesitant initially who completed both the pre-intervention (N=73) and post-intervention (N=68) aVHS

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 Change in Vaccine Hesitancy Scores Pre- and Post-Intervention., measured over Baseline (Pre-intervention) and Post-Intervention, up to 4 hours.

The primary endpoint is change in Vaccine Hesitancy Scale scores from before to after the educational intervention. It is a continuous measure, reported in units on a scale, with the mean and standard deviation specified as the summary measures. The stated assessment window is baseline before intervention and post-intervention, up to 4 hours.

The 8-item scale has a range of 1 to 5. A score of 3 or higher is described as indicating vaccine hesitancy; participants scoring at that threshold initially formed the primary outcome population. The registry says this population completed both pre- and post-intervention assessments, while listing N=73 for the pre-intervention assessment and N=68 for the post-intervention assessment. It does not clarify the relationship between those counts or provide the paired observations.

A continuous score can capture variation in degree of hesitancy rather than only whether a participant is above or below a threshold. A before-and-after measure can describe within-person change when both measurements are available. However, the registry record does not report the mean scores, the estimated change, its uncertainty, or a test of the primary endpoint. It also does not provide information about the scale’s measurement properties in this study. The endpoint therefore defines what the study intended to assess, but the record does not show the resulting numerical outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is a continuous score, and the registry specifies the mean and standard deviation as its summary statistics. For a continuous outcome, a mean describes the central level of measurements in a group, while a standard deviation describes how dispersed individual measurements are around that mean. These summaries would help characterize the scores before and after the intervention. Neither set of summaries is reported in the registry record.

What would a pre-post estimate represent?

For participants assessed at both time points, a within-person change estimate would compare each participant’s post-intervention score with that same participant’s baseline score. This approach preserves the pairing of repeated measurements. It differs from comparing two unrelated groups, because measurements from one person are generally connected to one another. The registry’s description refers to participants who completed both assessments, but it does not report the paired score data, an estimated change, or a statistical method for analyzing paired observations.

The assessment window is baseline and post-intervention, up to 4 hours. This is a short-term assessment window as described in the record. The registry does not state whether there were later assessments of the primary score, or report how the endpoint was analyzed over time. No statistical model or adjustment strategy is reported.

How should uncertainty be read?

In general, a confidence interval describes a range of values compatible with the data and a specified statistical procedure. Its width conveys precision: a narrower interval indicates greater precision than a wider interval under the same approach. A p-value, when used, summarizes how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the test assumptions. Neither measure supplies the missing outcome estimate, and neither alone describes practical importance. The registry record gives no confidence interval or p-value for the primary outcome.

Standard deviation and standard error have different purposes. Standard deviation describes variation among individual scores; standard error describes uncertainty in an estimated quantity, such as a mean, under an analysis model. The registry names standard deviation as the endpoint’s dispersion measure, but does not report standard errors or other uncertainty measures. No estimate can be reconstructed without the relevant summary statistics or participant-level observations.

What does the design allow?

In general, a single-group before-and-after design can describe how measurements differ across time in the observed participants. Because it lacks a concurrent comparison group, it cannot distinguish an intervention-associated change from other influences occurring during the same period. A randomized comparison can help address this problem by making assigned groups comparable on average, but the registry describes no random allocation and no separate control arm. The registry specifically identifies that there is not a randomized comparison and that arms are not a like-for-like control comparison.

The record lists a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. This is a planning exercise, not the trial’s own design, and it does not constitute observed power. The record does not report the observed effect needed to interpret such an illustration, nor does it report the trial’s sample-size justification. The illustration’s two-arm assumptions do not change the actual single-group design.

What is not available for evaluating the analysis?

The registry record lists no analyses and does not state a statistical test, model, covariate adjustment, or method for handling missing data. It does not explain whether the primary endpoint was assessed using a paired test, a model of repeated measurements, or another approach. The stated scale range and hesitancy threshold define the measure, but do not determine an appropriate analysis on their own. The analysis choice would need to account for the study question, available paired observations, and assumptions of the selected method. Without results and analytic details, no numerical inference about the primary outcome is possible.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Vaccine Hesitant")
n   <- c(68)
m   <- c(-0.4)
sp  <- c(0.63)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Vaccine Hesitant  68  -0.400  0.630  -0.552  -0.248

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures, including change in Vaccine Hesitancy Scale scores, rate of influenza vaccine uptake, and a pre-intervention altruism scale. It does not report a multiplicity strategy, such as whether one endpoint was designated as the sole basis for confirmatory inference or whether significance thresholds would be adjusted across outcomes. The record identifies a primary outcome, but does not describe how additional outcome analyses would affect interpretation.

Multiplicity matters in general when several outcomes or statistical tests are examined: the chance of at least one apparently notable finding can increase as more tests are considered. How to address that concern depends on the prespecified questions and analysis plan. The registry record does not report such a plan or any analyses, so it is not possible to determine how multiple outcomes were handled or whether outcome testing was confirmatory or exploratory.

The primary outcome description gives N=73 at baseline and N=68 after the intervention, while referring to participants who completed both assessments. The record does not explain the differing counts, identify the paired analysis sample, or describe why assessments may be unavailable. It also does not state whether missing observations were excluded, imputed, or addressed in another way. The amount and pattern of missing data, and any sensitivity analyses, are not reported in the registry record.

The analysis population is therefore not fully characterized. The record does not say whether all enrolled participants were included in each outcome analysis, or define a separate analysis population beyond the primary outcome description. No analysis details are listed. These omissions limit assessment of selection effects, missing-data assumptions, and the applicability of any outcome estimate; no such estimate is reported in this record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists one group, Vaccine Hesitant, with 510 participants at risk for serious adverse events and 0 affected. It also lists 510 at risk for other adverse events and 0 affected, with 0 deaths. No serious adverse event terms are listed among the most common terms.

These are registry safety counts. They should be read as the counts recorded for the group, not as proof that no adverse events occurred outside the recorded reporting process. The record does not state the safety observation period, provide event definitions, or describe how adverse events were collected or assessed. It also does not report further detail about the participants included in the safety denominator or the completeness of safety follow-up.

The primary outcome population has different assessment counts from the 510 participants listed at risk in the safety record. These figures refer to different record entries and should not be treated as interchangeable denominators. The safety counts do not address whether the intervention changed vaccine hesitancy or uptake. They describe only the adverse-event figures listed in the registry.

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

The record establishes that a completed single-group cohort study examined an educational intervention focused on herd immunity and vaccine hesitancy. Its primary endpoint was change in an 8-item Vaccine Hesitancy Scale among participants initially classified as hesitant. The record also identifies vaccination uptake and pre-intervention altruism as secondary outcomes. These details show what the study set out to measure; they do not show what happened to those measures.

No primary outcome estimate or analysis is reported in the registry record. There are no posted pre- and post-intervention means, estimated change, confidence interval, or p-value. The listed assessment counts do not provide enough information to recover an outcome estimate, and the record does not report the paired data. The same limitation applies to the secondary outcomes: their names are listed, but their numerical findings are not.

Accordingly, the registry record cannot support a conclusion that the intervention did or did not change hesitancy scores or vaccination uptake. It also cannot establish the size or precision of a potential change. A non-randomized, single-group design would in any case be unable to isolate an intervention effect from other causes of change, even if a before-and-after difference were reported.

In general, a statistical result needs to be considered alongside the outcome definition, analysis population, design, and uncertainty around the estimate. Here, the endpoint definition and design are described, but the analyses and estimates are not. The sensible interpretation is therefore limited to the study’s stated question and recorded design, rather than an inference about intervention effectiveness or lack of effect.

14. Why This Trial Matters Statistically

This study raises an important statistical distinction between measuring a change and attributing a change to an intervention. Repeating a continuous score before and after an educational activity can describe how the score differs over time among measured participants. Without a concurrent comparison group, however, the observed temporal pattern cannot isolate the contribution of the intervention. The distinction is central to interpreting any pre-post study, particularly when its title and stated purpose concern an effect.

The primary outcome is a scale score, while the study’s broader purpose includes vaccination uptake. These are related research questions but distinct outcomes. A change in a measure of hesitancy would not itself establish a change in uptake, and an uptake result would not provide the missing score analysis. The registry lists both outcome concepts but does not report their numerical findings.

The record also illustrates why analysis populations and missing assessments matter. It identifies different pre- and post-intervention assessment counts while describing a group that completed both. Clear reporting of paired sample counts, missingness, analysis methods, and uncertainty would be needed to judge how well an estimate represents the intended population. Those details are not reported in the registry record.

Finally, the planning illustration is distinct from the study’s actual design and cannot substitute for an outcome analysis. Planning calculations concern hypothetical sample-size conditions; they do not show what was observed or establish statistical power after a study. A registry entry that reports the design and endpoint but no analyses therefore has descriptive value while leaving the primary statistical question unresolved.

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 central limitation for interpreting this record is that the primary endpoint’s results are not reported. The registry defines the score and assessment window, but does not provide score summaries, an estimated change, uncertainty, or an analysis. As a result, the direction and magnitude of the measured outcome cannot be determined.

The single-group design has no randomized or concurrent control comparison. Any before-and-after difference, if reported elsewhere, would not alone establish that the intervention caused the change. The registry identifies no allocation and no masking. It does not report additional design features that could address alternative explanations for a temporal difference.

The primary outcome population is also unclear in a practical way: the description refers to people who completed both assessments but lists N=73 before intervention and N=68 after intervention. The record does not explain the difference or state the number included in a paired analysis. Missing-data reasons, methods, and sensitivity analyses are not reported. Participant characteristics beyond the stated eligibility and hesitancy classification are also not reported in the registry record.

The intervention is described broadly as educational and focused on herd immunity, especially its relevance to the local pediatric oncology community. The record does not describe its specific content or delivery. It does not report the statistical analysis plan, outcome-analysis methods, multiplicity handling, or secondary outcome results. These gaps limit evaluation of both implementation and statistical inference.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Promoting Altruism to Enhance Vaccine Acceptance — NCT04568590.
• Registry record last updated 2024-08-12; status last verified 2022-07.
• Results first posted 2024-08-12.
• 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

NCT04568590 is a completed, single-group cohort study sponsored by Wake Forest University Health Sciences. It evaluated an educational intervention about herd immunity among participants deemed vaccine hesitant and eligible for seasonal influenza vaccination. The registry lists enrollment as 510 and describes baseline and post-intervention assessment of the 8-item Vaccine Hesitancy Scale, with the post-intervention assessment occurring up to 4 hours after baseline.

The primary outcome population is described as initially hesitant participants completing both assessments, with N=73 listed at baseline and N=68 post-intervention. The record does not clarify the difference between these counts. It lists 6 outcome measures, including influenza vaccine uptake and a pre-intervention altruism scale, but reports no analyses. Numerical primary and secondary outcome results are not reported in the registry record.

Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths among 510 at risk. The registry does not report the safety observation period or further collection details.