FirstStep2Health Intervention: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for FirstStep2Health Intervention (NCT04164277), a randomized na study. The primary outcome is Moderate-to-vigorous Physical Activity (MVPA; Preschoolers)-AIM 1.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial with cluster randomization. Six Head Start centers were to be randomly assigned: three to the intervention and three to control. Because assignment occurs at the center level, children and caregivers recruited within the same center share a randomized cluster. Their outcomes may therefore be correlated, rather than behaving like independent observations. Statistical analysis needs to account for that design.

The intervention is described as lasting 16 weeks and combining caregiver activities, caregiver-preschooler learning, and a preschooler component at the Head Start center. The caregiver activities include a Facebook-based program and three face-to-face or virtual meetings. The control group was to continue usual Head Start activities during the intervention period; the record describes a brief program offered to control caregivers after post-intervention data collection.

The brief summary describes an average of six dyads recruited from each class, with a planned total of 144 dyads from 16 classes. The registered enrollment is 95. These figures describe different parts of the record, and no explanation of their difference is reported in the registry record. The record lists the trial status as completed. It gives a primary completion date of 2023-08-31 and a start date of 2021-09-20.

The primary outcome is preschoolers’ moderate-to-vigorous physical activity at 17 weeks. The registry also names fruit and vegetable intake, screen time, and the number of preschoolers who are overweight or obese as secondary outcomes. Although the record lists 14 outcome measures, it lists zero analyses. Thus, the design and planned outcome can be described, but the posted record does not provide estimates comparing the randomized groups.

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: 53 caregiver-preschoolers dyads (53 caregivers, 53 preschoolers) from 10 daycare centers were enrolled in the study, and 10 daycare centers were randomly assigned into the intervention (5 daycare centers, 53 dyads) and control (5 daycare centers, 42 dyads) group.

Preschoolers

Caregivers

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: The baseline sample included 53 caregiver-preschooler dyads (total 106 individuals, 53 caregivers, 53 preschoolers) in the intervention group and 42 caregiver-preschooler dyads (total 84 individuals, 42 caregivers, 42 preschoolers) in the control group.

6. Primary Endpoint

The registry lists the primary outcome as Moderate-to-vigorous Physical Activity (MVPA; Preschoolers)-AIM 1, measured over Moderate-to-vigorous physical activity at 17 weeks.

The primary endpoint is preschoolers’ moderate-to-vigorous physical activity at 17 weeks, expressed as a mean in minutes per hour. Physical activity is measured using an ActiGraph GT3X accelerometer. The registry describes accelerometer wear over seven days and says that movement counts are used to estimate minutes of activity. It specifies 15-second epochs and thresholds for classifying moderate and vigorous activity; intervals meeting the moderate-activity threshold are summed to determine minutes of moderate-to-vigorous activity.

An accelerometer offers a device-based measure of movement rather than relying only on a caregiver’s report. A mean in minutes per hour gives a group-level summary of measured activity during the monitoring period. The comparison of group means at the stated follow-up would address whether recorded activity differed between children assigned through intervention and control centers.

The endpoint is a measure of physical activity, not a direct measure of obesity or of long-term health. The registry record does not report the group means, standard deviations, number of children with usable accelerometer data, or an estimated between-group difference. Consequently, the meaning and precision of any observed contrast cannot be assessed from the posted outcome information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The design and reporting determine which statistical interpretations are possible. The registry describes a cluster-randomized, parallel-group study, names a continuous primary outcome, and records no analyses. The following concepts explain what a suitable analysis would need to address in general; they are not a description of an analysis reported for this trial.

Why does cluster randomization matter?

Random assignment took place at the Head Start center level. Children and caregivers within a center therefore share the same assigned group and may also share experiences, staff, and setting. Their measurements can be correlated. When observations are correlated, treating each participant as if independently randomized can make standard errors too small and confidence intervals too narrow. A suitable analysis generally accounts for clustering, for example through a model or variance estimate that reflects the randomized center. The registry record does not report the statistical method used to handle clustering, and lists zero analyses.

The number of randomized centers is limited to six, with three assigned to each group in the design description. Cluster-level assignment means the amount of independent information is not captured just by counting individual participants. The analysis would also need to consider how many centers and participants contributed outcome data, and whether the method’s assumptions are credible for this design. The registry record does not report endpoint-specific counts or those analytic details.

What does the endpoint summary represent?

The primary outcome is a continuous measure, with the mean and standard deviation designated as the summary format. A mean describes the average measured activity in a group. A standard deviation describes how spread out individual measurements are around that group mean. The standard deviation is not the uncertainty of the mean difference; that uncertainty also depends on the analysis design, sample information, and clustering.

The accelerometer procedure is intended to translate movement counts into minutes of moderate-to-vigorous activity. Device-based measurement can reduce dependence on recall, but interpretation still depends on monitoring completeness and the processing rules. The registry describes the wear instructions, monitoring period, epoch length, and count thresholds. It does not report how many records met any data-quality criteria, how incomplete monitoring was handled, or the observed endpoint summaries.

How would a group comparison be interpreted?

A comparison of means would estimate the difference in average minutes per hour between the intervention and control groups at the specified follow-up, using an analysis that accounts for center-level randomization. The estimated contrast would need an uncertainty measure, such as a confidence interval, to show how precisely the data locate the difference. In general, a confidence interval is calculated under a statistical model and reflects both observed variability and the design assumptions. It does not guarantee that the true effect lies within its bounds.

A p-value, in general, is a measure of compatibility between the observed data and a specified null hypothesis under the chosen model. It is not the probability that the null hypothesis is true, nor does it measure clinical importance. A p-value alone would not convey the magnitude or precision of a difference. In this registry record, no group comparison, confidence interval, or p-value is posted, so none can be interpreted.

What do the planning illustrations mean?

The registry describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The stated effect to detect is expressed as a fraction of the observed effect. For non-time-to-event outcomes, such illustrations are described as participants per arm. They are planning scenarios, not observed trial findings and not observed power. No numerical illustration values or observed primary-outcome effect are reported in the registry record, so the scenarios cannot be assessed quantitatively.

In general, such planning calculations ask how much information a future study might need under selected assumptions. They do not show that the completed study had a particular probability of detecting an effect, and they do not replace the actual uncertainty around a trial estimate. Their interpretation depends on the assumed effect and analysis model. The registry record does not report the trial’s own sample-size justification, so it cannot be determined whether these illustrative assumptions were used in the trial’s design.

Why is an independent recalculation not appropriate?

A simple recalculation from group summaries would treat the data as if individual participants had been independently randomized. That does not match the center-level allocation described in the registry record. The record explicitly notes that such an individual-level re-analysis would be misleading and indicates that only the sponsor’s own analysis is appropriate. However, the record lists zero analyses and provides no primary-outcome estimates to interpret. Without the sponsor’s analysis results and relevant details, the effect and its uncertainty cannot be independently assessed.

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("Intervention", "Control")
n   <- c(53, 42)
m   <- c(7.51, 7.46)
sp  <- c(3, 2.17)
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  Intervention  53  7.510  3.000  6.683  8.337
CARM  Control  42  7.460  2.170  6.784  8.136

11. Multiplicity, Missing Data and Analysis Populations

The registry names a primary outcome and lists secondary outcomes that include fruit and vegetable intake, screen time, and the number of preschoolers who are overweight or obese. It also records 14 outcome measures. When a study examines multiple outcomes or multiple analyses, there is a general risk that at least one result may appear noteworthy by chance. Prespecified outcome priorities and multiplicity procedures can help readers understand how such results were handled.

The registry record does not report whether multiplicity was addressed, whether any secondary outcomes were prioritized, or whether an analysis plan specified adjustments. It lists zero analyses, so no outcome-specific estimates or tests are available to assess. These details are not reported in the registry record.

The record also does not report missing-data methods, endpoint-specific denominators, or the analysis population used for any outcome. It is therefore not possible to determine how missing accelerometer observations, incomplete monitoring, or withdrawal from measurement were handled. In general, missing-data handling can affect both the estimate and its uncertainty, especially when missingness differs between groups or relates to participant characteristics or outcomes.

The planned cluster randomization also makes the analysis population important: a suitable analysis should retain the randomized assignment and account for the center-level allocation. The registry record does not describe whether all randomized centers or enrolled participants were included in an analysis, and it does not state how any unavailable outcome data were handled. No assumptions about those procedures can be made from the posted 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 reports adverse-event counts separately for preschoolers and caregivers in the intervention and control groups. For intervention preschoolers, 53 were listed at risk for serious adverse events and 53 for other adverse events; zero events were reported in both categories. For control preschoolers, the corresponding at-risk counts were 42 and 42, with zero serious and zero other adverse events. For intervention caregivers, 53 were listed at risk in each category, with zero events reported. For control caregivers, 42 were listed at risk in each category, also with zero events reported. Deaths are recorded as zero in all four groups.

These are the counts recorded in the registry, not a comparison of safety rates adjusted for the cluster-randomized design. The record lists no serious adverse-event terms. A count of zero means no events in that category were reported for the listed group in this record; it should not be read as proof that no unrecorded or unmeasured events occurred. The record does not provide additional detail about how adverse events were collected or adjudicated.

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

The registry record describes a completed cluster-randomized study of a 16-week intergenerational intervention and identifies preschoolers’ moderate-to-vigorous physical activity at 17 weeks as the primary endpoint. It also describes the intervention’s caregiver, caregiver-preschooler learning, and center-based components, along with usual Head Start activities as the comparison condition. These details clarify the question the study was designed to address.

What the record does not provide is the primary-outcome result. There are no posted group means, standard deviations, estimated differences, confidence intervals, or p-values, and the record lists zero analyses. Accordingly, the posted information cannot establish whether physical activity differed between groups, the size of any difference, or how precisely it was estimated. It also cannot establish findings for the named secondary outcomes.

The design has an important statistical feature: Head Start centers, not individual dyads, were randomized. Any valid comparison needs to reflect that clustering. The registry record cautions against simple individual-level recalculation and does not supply the sponsor analysis results needed to evaluate the outcome. Planning illustrations, where considered, are not a substitute for an observed estimate and do not represent observed power.

The registered enrollment is 95, while the brief summary describes a planned total of 144 dyads. The record does not explain that distinction. The safety counts report zero serious adverse events, zero other adverse events, and zero deaths in the listed groups, but these counts should be interpreted as registry-reported observations rather than proof of no possible harms.

In short, the record supports interpretation of the trial’s design, intended measurement, and recorded safety counts. It does not support a conclusion about the intervention’s effect on the primary endpoint or any other outcome.

14. Why This Trial Matters Statistically

This trial is statistically notable because its randomized units are Head Start centers while the primary outcome is measured in individual preschoolers. That structure affects how information is counted and how uncertainty should be estimated. Recognizing the cluster design is essential: a participant-level calculation that ignores shared center assignment could give misleading precision.

The registry also illustrates the distinction between a defined endpoint and an available result. It gives a detailed description of how accelerometer data were intended to represent preschoolers’ moderate-to-vigorous physical activity, including the follow-up time and unit. However, the record lists zero analyses and no group estimates. A clear measurement plan alone cannot show the direction, magnitude, or precision of an outcome difference.

There is also a difference between a recruitment plan and registered enrollment. The brief summary describes 144 planned dyads, whereas the enrollment entry is 95. Without an explanation or endpoint-specific participant counts, readers cannot determine how recruitment, follow-up, and usable measurement relate to one another.

Finally, planning illustrations and observed trial findings answer different questions. Planning scenarios depend on assumptions about an effect and an analysis; they are not evidence that the completed study detected a particular effect. The absence of posted analysis results means those illustrations cannot fill the gap. Together, these features make the registry record useful for understanding the intended design while limiting the conclusions available about outcomes.

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 important limitation for interpreting this trial from the registry record is the absence of posted outcome analyses. Although the record identifies a primary endpoint and lists 14 outcome measures, it reports zero analyses. No group summaries, effect estimates, or uncertainty measures are available. The record therefore does not permit assessment of the primary endpoint’s result or precision.

The cluster-randomized design requires analysis that accounts for center-level assignment. The record cautions that a simple individual-level recalculation would be misleading, but does not report the sponsor’s analysis method or results. The number of centers is six in the design description, which also makes it important to know how the analysis handled the limited number of randomized clusters. Those analysis details are not reported in the registry record.

The registered enrollment is 95, while the study summary describes a planned 144 dyads from 16 classes. The record does not explain the difference or report how many participants contributed usable accelerometer data. It also does not report missing-data procedures, the analysis population, or whether all centers and enrolled participants were included in outcome analyses.

The primary endpoint depends on accelerometer data processing and wear. The registry describes the monitoring and processing approach, but does not report data completeness or quality information. The adverse-event entries list zero events in the named categories, but provide limited detail about collection and assessment. These limitations concern what can be learned from the registry record; they do not establish what occurred outside the information recorded there.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: FirstStep2Health Intervention — NCT04164277.
• Registry record last updated 2024-08-02; status last verified 2024-07.
• Results first posted 2024-08-02.
• 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

The registry identifies NCT04164277 as a completed, randomized, single-masked, parallel-group cluster trial of the FirstStep2Health Intervention. The design description assigns six Head Start centers to intervention or control. The intervention is described as a 16-week program for preschoolers and caregivers; the comparator is usual Head Start activities during that period.

The primary endpoint is preschoolers’ mean moderate-to-vigorous physical activity in minutes per hour at 17 weeks, measured using an ActiGraph GT3X accelerometer. The record lists enrollment of 95 and describes a planned recruitment of 144 dyads in its brief summary. It lists 14 outcome measures and zero analyses. No primary or secondary outcome estimates are reported in the registry record. The adverse-event entries record zero serious events, zero other events, and zero deaths in the listed groups.