mHealth-Assisted Conditional Cash Transfers to Improve Timeliness of Vaccinations (D0271): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for mHealth-Assisted Conditional Cash Transfers to Improve Timeliness of Vaccinations (D0271) (NCT03252288), a randomized na study. The primary outcome is Number of Timely Vaccinations Received.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group trial with no masking. The registry record lists three groups: no intervention, reminders only, and reminders with conditional financial transfers. The reminders were scheduled for one week and one day before each vaccination date. In the combined-intervention arm, a conditional transfer was made for each on-time vaccination visit. The record describes the transfers as conditional but does not report their amounts or other implementation details.

The registry lists enrollment of 412. It gives a start date of 2017-08-15 and a primary completion date of 2018-10-13, and the study status is completed. The listed phase is NA. The sponsor is Duke University. The registry describes the study as evaluating the feasibility and efficacy of mHealth-assisted conditional cash transfers for improving timely childhood vaccination, and as a basis for a pragmatic randomized controlled trial. Further details about the trial setting, recruitment, allocation procedures, or feasibility measures are not reported in the registry record.

Vaccinations were scheduled at birth and at ages 6, 10, and 14 weeks. The primary outcome timeframe extends up to 6 months after birth. The registry notes that delays in the 6- and/or 10-week vaccinations shift subsequent due dates, and that observations beyond 6 months after birth are censored. The listed secondary outcome is the number of vaccinations received. The registry record does not report group-specific enrollment, intervention adherence, or the number of participants included in the primary-outcome analysis.

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: Participants in follow-up survey without missing data on vaccinations and per-protocol study arm

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.

Population: Of 412 participants enrolled, 14 were disenrolled due to maternal death (n=1), child death (n=11), or withdrawal (n=2), leaving an initial sample of 398 participants. 79 participants were lost to follow-up. Baseline data were lost (due to tablet failure) for 6 participants. The effective enrollment into the trial was N=313. N=310 had valid data on study outcomes and per-protocol assignment to study arms.

6. Primary Endpoint

The registry lists the primary outcome as Number of Timely Vaccinations Received, measured over Up to 6 months after birth.

The primary endpoint is titled “Number of Timely Vaccinations Received.” It concerns vaccinations received within four weeks of their scheduled dates, with timeliness assessed separately for each vaccination. The schedule includes vaccinations due at birth and at ages 6, 10, and 14 weeks. If a vaccination at 6 and/or 10 weeks is delayed, later due dates shift accordingly. Observations after 6 months after birth are censored.

A count-based endpoint can describe how many timely vaccination events participants receive over the specified schedule. It reflects more than whether a participant had any timely vaccination: the outcome definition considers each scheduled vaccination independently. This makes the timing rule and the schedule important to interpretation, since a delayed earlier vaccination can shift later due dates.

The registry identifies participants in a follow-up survey without missing vaccination data and in a per-protocol study arm as the primary-outcome population. It labels the outcome unit as participants and the parameter as a count of participants. The record does not explain how the outcome was summarized across participants, or give the distribution of timely vaccinations by group. It also does not report a primary-outcome estimate or comparison. Consequently, the endpoint definition is available, but its observed results and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods can clarify how a randomized trial is intended to compare groups, but the record does not report a statistical analysis plan or primary-outcome analysis. The concepts below are general explanations, not a description of analyses documented for this trial.

What does randomization contribute?

In general, randomization assigns participants to study groups using a chance-based process. Its purpose is to reduce systematic differences between groups at assignment, so that a later contrast can be interpreted as evidence about the assigned interventions, subject to issues such as missing data, adherence, and chance variation. This trial is listed as randomized and parallel-group. The method used to generate the assignment sequence, how assignments were concealed, and whether allocation was stratified are not reported in the registry record.

A parallel-group design assigns participants to one group and compares outcomes across groups. Here the listed groups are no intervention, reminders only, and reminders plus conditional financial transfers. The interventions make two distinct comparisons of interest: reminders against no intervention, and adding conditional transfers to reminders. The registry record does not state which contrast was designated as the principal statistical comparison or how comparisons among all three groups were planned.

What does the endpoint definition imply?

The primary outcome concerns a count of timely vaccinations, assessed separately for each scheduled vaccination. A count outcome can have a range of possible values rather than being limited to a single yes-or-no outcome. General methods for count data may summarize a mean count, compare count distributions, or model counts, but the appropriate method depends on the observed data and analysis objective. The registry record does not report the summary measure, model, or test used for this endpoint.

Count outcomes can show over-dispersion when variation in the observed counts exceeds what a simple count model expects. In general, ignoring over-dispersion can make uncertainty estimates too small and tests too optimistic. This is a general consideration only: dispersion is listed as null for the primary outcome, and the registry record does not report an assessment of the outcome’s distribution or an adjustment for over-dispersion.

The timeliness rule is tied to changing due dates: delays in the 6- and/or 10-week vaccinations shift later due dates. This means the endpoint is not simply a count against an unchanging calendar schedule. The registry record defines how timeliness was judged but does not give further detail on how shifted schedules were implemented in the analysis.

How should uncertainty be read?

In general, a confidence interval gives a range of estimates compatible with the data and a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, while an interval that includes no difference may be consistent with a range of effects. A p-value, when reported, describes how unusual data at least as incompatible with a specified null hypothesis would be under the assumptions of a statistical test. Neither measure gives the probability that a hypothesis is true. No confidence intervals or p-values for the primary outcome are reported in the registry record, so the precision and statistical evidence for a group difference cannot be assessed.

Randomization does not eliminate uncertainty, and a numerical difference between observed groups would not by itself show that the interventions caused the difference. General interpretation considers the size and precision of the estimate, the analysis population, missing data, and the prespecified comparison. The registry record does not provide the outcome estimates needed for this assessment.

What do planning sample sizes mean?

General sample-size calculations estimate how many participants might be needed to detect an assumed effect under specified design assumptions. The planning illustrations associated with the record are described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is a stated fraction of the observed effect. These are planning illustrations, not observed power, and they should not be read as the trial’s achieved power or as the original design justification. The registry record does not report the trial’s own sample-size justification. Because the primary-outcome group results are not reported in the registry record, the illustrations do not substitute for an interpretable estimate of the observed effect.

The record does not report interim analyses, model specifications, covariate adjustments, or sensitivity analyses. Their presence, absence, or results should not be inferred from the randomized design alone.

10. Multiplicity, Missing Data and Analysis Populations

The trial lists a primary outcome, “Number of Timely Vaccinations Received,” and a secondary outcome, “Number of Vaccinations Received.” It also has three study groups, which could permit more than one pairwise comparison. The registry record does not report how many comparisons were planned, which comparison was primary, whether the secondary outcome was formally tested, or how multiplicity was addressed. Without a documented plan, the risk of false-positive findings across multiple tests cannot be assessed. No outcome analyses are listed in the registry record.

The primary-outcome population is described as participants in a follow-up survey without missing vaccination data and in a per-protocol study arm. This is a population definition, not a full account of missing-data handling. The record does not report how many participants lacked follow-up, how many had missing vaccination information, why data were missing, or whether any imputation or sensitivity analyses were used. It also does not provide arm-specific numbers for the primary-outcome population.

In general, excluding participants with missing outcome data can affect a comparison if the chance of missingness is related to group assignment or to vaccination outcomes. A per-protocol population can also differ from the population defined by randomized assignment, particularly if adherence or eligibility for analysis varies across groups. These are general concerns; the registry record does not provide enough information to determine whether either issue affected this trial’s results. The number analyzed and the relationship between that population and all randomized participants are not reported in the registry record.

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 serious-adverse-event listing records 0 affected participants among 239 at risk in the no-intervention group, 0 among 67 at risk in the reminders-only group, and 0 among 106 at risk in the reminders-plus-conditional-financial-transfer group. For other adverse events, the listed affected counts are also 0 in each group, with the same at-risk counts. These are descriptive counts in the registry record; they do not establish that no events occurred outside the recorded categories or reporting period.

The listing also records deaths of 12 in the no-intervention group, 0 in the reminders-only group, and 0 in the reminders-plus-conditional-financial-transfer group. The causes, timing, and relationship of these deaths to study participation or intervention are not reported in the registry record. The record does not provide explanations for the differing at-risk denominators, event ascertainment details, or group-specific safety analyses. These counts should not be interpreted as evidence that the interventions caused or prevented deaths, and the absence of reported affected participants in the adverse-event fields should not be treated as proof of no risk.

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

The study addresses a practical question about whether mobile-health reminders, alone or paired with conditional financial transfers, can help improve the timing of childhood vaccinations. Its randomized, parallel-group design is relevant to comparing these intervention strategies with no intervention. The registry record also gives a specific timeliness definition, a vaccination schedule, and an outcome timeframe, which are necessary to understand what the intended primary measure represents.

However, the registry record does not report the primary-outcome counts by group, an effect estimate, or a statistical comparison. It therefore cannot show whether one group had more timely vaccinations, how large any difference was, or how precisely a difference was estimated. The completed status and enrollment count do not answer those questions. The record also does not report results for the listed secondary outcome, the number analyzed for the primary outcome, or the analysis methods used.

Consequently, the trial record supports an account of the research question and design, but not a conclusion about the intervention’s effect on timely vaccination. The serious-adverse-event figures are likewise limited: the record lists zero affected participants for the event fields and records deaths in one group, but does not provide enough context to determine causes or relationships. No conclusion about benefit or harm can be drawn from those counts alone.

More broadly, a trial result is interpreted through both its estimate and its uncertainty, along with the analysis population, missing data, and planned comparisons. Those elements are not fully reported for this study in the registry record. The record should therefore be read as an incomplete statistical account of a completed trial rather than as a quantitative report of its primary findings.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it distinguishes the contribution of reminders from the potential added contribution of conditional financial transfers. A no-intervention group offers one comparison for the reminder strategy, while the reminders-only and combined-intervention groups create a comparison relevant to adding a transfer to reminders. Keeping these questions distinct matters: evidence about one contrast would not automatically answer the other.

The endpoint also requires careful operational definition. Timeliness is assessed for each vaccination relative to its scheduled date, and later due dates shift if certain earlier vaccinations are delayed. The four-week window defines what counts as timely, while censoring observations beyond 6 months after birth defines the observation boundary. These rules shape the measured outcome and should be understood before interpreting any future group comparison.

At the same time, the registry record illustrates why design information is not a substitute for results. Enrollment of 412 and a completed status do not reveal the number analyzed, the distribution of timely vaccinations, or the precision of a group contrast. Without those results, readers cannot evaluate the magnitude or uncertainty of the statistical findings. The record also does not document the planned handling of multiple comparisons or missing data, issues that can affect interpretation even in randomized studies.

The study’s stated intention to inform a pragmatic randomized trial makes transparent reporting especially useful. A clear account of group outcomes, analysis populations, missingness, and uncertainty would help readers judge whether the intervention contrasts are informative and how they might apply to settings beyond the trial. Those result details are not reported in the registry record.

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 registry record leaves important trial details unreported. It does not describe the setting, eligibility criteria, recruitment procedures, assignment sequence, allocation concealment, or implementation fidelity. It gives overall enrollment but not allocation counts by group. Although the primary-outcome population is defined, the number included in it and the number excluded are not reported.

Primary-outcome results are absent: the record does not give arm-level counts, an effect estimate, a confidence interval, or a p-value. The listed secondary outcome also has no reported results. The statistical analysis plan, model, handling of the count outcome, and any sensitivity analyses are not reported in the registry record. Nor does the record explain its approach to multiple comparisons or missing data.

The outcome definition depends on a scheduled vaccination date and allows later due dates to shift after specified delays. The registry describes this rule but does not report implementation details. The primary-outcome timeframe is up to 6 months after birth, with observations beyond that point censored; further information about follow-up completeness is not reported. The serious-adverse-event listing includes group counts but does not provide event descriptions, causes, timing, or attribution. These reporting gaps limit assessment of both the primary comparison and the safety information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: mHealth-Assisted Conditional Cash Transfers to Improve Timeliness of Vaccinations (D0271) — NCT03252288.
• Registry record last updated 2025-03-07; status last verified 2025-03.
• Results first posted 2025-03-07.
• 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

NCT03252288 is a completed randomized, parallel-group trial sponsored by Duke University, with no masking and enrollment of 412. It compared no intervention, reminders before scheduled vaccination dates, and reminders paired with conditional financial transfers. The primary outcome was the number of timely vaccinations received, with timeliness defined as vaccination within four weeks of the scheduled date and follow-up described up to 6 months after birth.

The registry record does not report primary- or secondary-outcome results, group-level primary analyses, or statistical comparisons. It defines a per-protocol follow-up-survey population for the primary outcome but does not report how many participants were analyzed. Serious-adverse-event affected counts are listed as 0 in each group; death counts are 12, 0, and 0 across the no-intervention, reminders-only, and combined-intervention groups, respectively. Causes and relationships are not reported in the registry record.