Motivations to Transplant Registry Participation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Motivations to Transplant Registry Participation (NCT05595382), a randomized na study. The primary outcome is Intention to Register.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-masked, parallel-group behavioral study comparing an emotional appeal with a rational appeal. The record lists enrollment as 397 and the study status as completed. The study start date is 2022-10-10, and the primary completion date is 2023-11-06. The sponsor is Rutgers, The State University of New Jersey.

Participants were randomly assigned to an emotional or rational appeal, with assignment stratified by sex. Stratification means that the random assignment process takes the stated characteristic into account when forming allocation groups. It can help balance that characteristic across arms, although the registry does not report the allocation details or resulting distributions. The identity of the people who were masked is not reported in the registry record, so the masking description cannot be interpreted more specifically.

The primary outcome, intention to register, was measured before and after the experimental manipulation. The registry also lists mood and knowledge as secondary outcomes. It records three outcome measures and three analyses, but does not provide numerical results or explain how those analyses correspond to each outcome and assessment time.

The record does not describe the specific appeal materials, recruitment procedures, eligibility criteria beyond the population description, or the setting in detail. It also does not report the protocol, the rationale for the enrollment target, or whether the completed study differed from its planned conduct. Those details are not reported in the registry record.

4. Participant Flow and Accounting

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

Before assignment: Participants were randomized after completing study baseline measures. 36 participants dropped out before reaching randomization.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Likelihood to join registry for all randomized study participants on a 1-7 scale with higher scores indicating a greater likelihood of joining (better outcome).

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 Intention to Register, measured over Baseline and after the experimental manipulation (Post-Intervention).

The primary endpoint is intention to register for the NMDP/Be The Match registry. Participants rated their likelihood of registering on a 1-7 scale, with higher scores indicating greater intention. The registry describes this as a continuous measure summarized by a mean with a standard error. It was assessed at baseline and after the experimental manipulation.

Intention is a measure of stated likelihood, not a record of actual registration or donation. It is used in this study to assess participants’ immediate responses to the appeals. A baseline assessment can describe intention before exposure to the study material, while a post-intervention assessment captures intention after exposure. The registry record does not state a single primary contrast, such as a comparison of post-intervention scores, a comparison of change from baseline, or an adjusted model. It also does not report the mean scores, standard errors, or an estimated difference for either arm.

Because the endpoint is a rating scale, the mean describes the average score in a group. The standard error describes the precision of an estimated mean, rather than the spread of individual scores. Without the numerical estimates and a defined between-arm comparison, the direction and precision of any difference in intention cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the primary outcome as continuous and summarizes it as a mean with a standard error. A mean is the arithmetic average of participants’ scale scores in a group. It gives a compact description of the group’s responses, but it does not show the full distribution. Participants may have similar scores or widely varying scores while producing the same mean.

What does the standard error describe?

In general, a standard error describes the precision of an estimate, such as a group mean. It is not the same as the standard deviation, which describes variability among individual observations. A smaller standard error indicates a more precise estimate under the assumptions of the analysis; it does not by itself show that a difference between groups is important or unlikely to be due to chance. The registry does not report the standard errors for the intention scores.

How should baseline and post-intervention measurements be understood?

Baseline and post-intervention ratings are repeated measurements of intention. A comparison can focus on the post-intervention scores, on the change within each arm, or on the difference in change between arms. These approaches answer related but distinct questions and can use different statistical models. General statistical practice does not determine which approach this study used. The registry record does not report the primary contrast, model, or adjustment for baseline scores.

Random assignment supports a comparison between groups by allocating participants through a chance-based process. Stratification by sex means assignment was organized with sex taken into account. These design features describe allocation; they do not show that all other characteristics were balanced or that outcome data were complete. The registry does not report the allocation procedure in detail or the characteristics of participants by arm.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with an estimated effect under the statistical model and its assumptions. It communicates uncertainty around the estimate, complementing a point estimate such as a difference in mean scores. The registry does not report a confidence interval or a point estimate for the primary comparison. Consequently, neither the size nor the precision of an effect can be evaluated from the posted registry information.

What can be inferred from the analysis descriptions?

The record gives the outcome summary type but not the inferential analysis plan. It does not report the statistical test, model specification, covariates, treatment of baseline scores, handling of incomplete observations, or a prespecified significance threshold for the primary comparison. General methods such as a two-group comparison of means or a repeated-measures model could be relevant to this design, but the registry does not establish that either was used. No specific method should be attributed to the study without a report of it.

The registry lists three outcome measures and three analyses. That count does not reveal which analyses were performed, whether they were prespecified, or whether outcomes were analyzed at multiple time points. The method for controlling, or not controlling, the chance of false-positive findings across analyses is not reported in the registry record.

How should planning calculations be read?

General sample-size planning asks how many participants per arm might be needed to detect a specified effect under chosen assumptions. The planning illustration associated with the posted material is based on a fraction of the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such values are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. A calculation based on an observed effect is also dependent on that estimate, which may be imprecise. The registry record does not report the trial’s own sample-size justification or statistical plan, and no planning value should be treated as an observed trial result.

In general, over-dispersion matters when data vary more than a model assumes, because standard errors and resulting inferences can then be misleading. This concept is not a reported feature of the intention scale analysis, and the registry does not describe a model for which over-dispersion was assessed. The continuous outcome description alone does not establish that a particular model or diagnostic was used.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and three analyses, including the primary intention outcome and secondary outcomes of mood and knowledge. It does not describe the analysis-to-outcome mapping, the number of comparisons within each analysis, or whether additional time-point comparisons were conducted. The plan for handling multiplicity is not reported in the registry record.

In general, testing several outcomes or comparisons can increase the chance of at least one apparently notable result arising by chance. Statistical plans may address this through a prespecified hierarchy, adjustment, or cautious interpretation. None of these approaches can be attributed to this study from the registry description. No p-values or confidence intervals for the outcomes are reported, so the effect of any multiplicity approach cannot be assessed.

Missing outcome data and their handling are not reported in the registry record. The record does not state how many participants completed each assessment, whether missingness differed between arms, or whether the analysis used complete cases, imputation, or another method. Enrollment and the adverse-event denominators do not establish the number of observations used for the primary outcome analysis.

The outcome population is described as all randomized study participants, but the registry does not specify the analysis population actually used. It does not say whether the analysis followed an intention-to-treat approach, included only participants with observed post-intervention scores, or used another definition. These omissions matter because exclusions and missing observations can affect the interpretation of a randomized comparison.

11. 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’s adverse-event record lists the Emotional Group with 181 participants at risk for serious adverse events and 181 at risk for other adverse events; it records 0 serious adverse events, 0 other adverse events, and 0 deaths. For the Rational Group, it lists 180 participants at risk for serious adverse events and 180 at risk for other adverse events; it records 0 serious adverse events, 0 other adverse events, and 0 deaths.

These are the event counts recorded in the registry. A zero count means no events of the listed type were recorded in the corresponding data, not that the possibility of an event has been ruled out. The registry record does not describe the event collection procedures, the observation period for safety reporting, or how completely adverse events were ascertained. The at-risk counts are safety reporting denominators and should not be assumed to equal the number of participants included in the primary outcome analysis.

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

This study addresses a behavioral question: whether an emotional appeal or a rational appeal is associated with different stated intentions to join a stem cell donor registry. Its primary measure is a 1-7 rating of likelihood to register, recorded at baseline and after the experimental manipulation. The scale’s higher-is-greater-intention direction makes the construct clear, while the randomized allocation describes how the study intended to compare the appeal groups.

The registry record does not report numerical primary outcome results. It therefore cannot establish the observed direction, size, or precision of a difference between the groups. It also cannot show whether intentions changed from baseline, whether any change differed between groups, or whether results were consistent across the secondary outcomes. Those are empirical questions that require outcome estimates and an account of the analyses.

Even a reported difference in intention would describe a measured rating, not necessarily actual registry enrollment or donation behavior. The registry’s outcome description concerns participants’ stated likelihood of registering. It does not report a behavioral measure of completed registration. General interpretation should keep those constructs distinct.

The study record also does not report details needed to evaluate how broadly results might apply, such as participant characteristics beyond the college-student description or the specific presentation of the appeals. The completed status and enrollment entry do not supply those missing details. The safety counts likewise address recorded adverse events and do not answer the primary question about intention.

The defensible conclusion is limited: the registry describes a randomized comparison with a defined intention scale and baseline and post-intervention assessments, but does not report the primary outcome findings. Without estimates and uncertainty measures, a conclusion about the comparative effect of the appeals would be unsupported.

13. Why This Trial Matters Statistically

The statistical interest of this study lies in the gap between a clearly stated behavioral question and the information needed to answer it quantitatively. Random assignment and sex-stratified allocation provide a framework for comparing emotional and rational appeals. Repeated measurement at baseline and after the manipulation creates a further analytical choice: the comparison may concern post-intervention scores, within-person change, or a difference in change. Those estimands are not interchangeable, so naming the outcome alone is not enough to understand the analysis.

The endpoint is also a useful reminder that an outcome can be measured precisely without being a direct behavioral endpoint. A rating of likelihood to register represents intention on a defined scale. It may be relevant to the study’s question, but it should not be read as a count of registrations. Clear interpretation depends on preserving that distinction.

Reporting means, uncertainty estimates, the chosen contrast, and the analysis population would allow readers to judge the magnitude and precision of the primary comparison. Reporting missing-data handling and multiplicity decisions would clarify how the outcome and secondary analyses were interpreted. Those statistical details are not reported in the registry record.

As recorded, the design and measurement are identifiable, but the evidence needed to quantify the result is absent. That makes this an example of why trial status and a stated endpoint are not substitutes for a results report. The registry establishes what the study intended to measure, not what the comparison found.

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 numerical primary outcome results in the registry record. No group means, standard errors, effect estimate, confidence interval, or p-value are reported. The result therefore cannot be quantified or assessed for precision.

The record specifies baseline and post-intervention assessments but does not define the primary contrast or analytical model. It is not possible to tell whether the intended comparison concerns post-intervention scores, change from baseline, or a baseline-adjusted estimate. The treatment of repeated observations is not reported in the registry record.

Details of the intervention materials are limited to the labels emotional appeal and rational appeal. The content, duration, and delivery are not reported, which restricts interpretation of what exposure the randomized groups actually received. The record states that masking was single but does not identify who was masked.

Participant flow, outcome completion, missing-data handling, and the analysis population are not reported. The registry describes the primary outcome population as all randomized study participants, but does not establish how the reported analyses were conducted. The study population is described as college students, while further demographic and setting details are not reported in the registry record.

The record lists secondary outcomes and analyses but does not provide their results or a multiplicity plan. It also does not report the trial’s own sample-size justification or full statistical plan. These gaps leave important aspects of analysis and generalizability unresolved, beyond the absence of the primary outcome estimates.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Motivations to Transplant Registry Participation — NCT05595382.
• Registry record last updated 2025-04-18; status last verified 2025-04.
• Results first posted 2025-04-18.
• 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.

18. Record Summary

NCT05595382, titled “Motivations to Transplant Registry Participation,” is recorded as a completed randomized, single-masked, parallel-group behavioral study sponsored by Rutgers, The State University of New Jersey. Enrollment is listed as 397. Participants were assigned to an emotional or rational appeal, with randomization stratified by sex.

The primary outcome was intention to register, rated on a 1-7 scale at baseline and after the experimental manipulation. Higher scores indicate greater intention. Mood and knowledge are listed as secondary outcomes. Numerical primary and secondary outcome results, the specific statistical analyses, missing-data procedures, and the analysis population are not reported in the registry record.