For the Health of Our Children--Clinic Based Treatment of Childhood Obesity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for For the Health of Our Children--Clinic Based Treatment of Childhood Obesity (NCT01625910), a randomized na study. The primary outcome is Body Mass Index Z-score Change.

2. Clinical Question

3. Trial Design

NCT01625910, titled “For the Health of Our Children--Clinic Based Treatment of Childhood Obesity,” was a completed randomized, parallel-group study sponsored by the University of Minnesota. The registry lists the phase as not applicable and the masking as single. Enrollment is recorded as 72. The study start is listed as 2011-09 and primary completion as 2012-08.

The registry describes assignment to recommended treatment guidelines or a control condition. The active intervention was behavioral counseling using motivational interviewing to encourage healthy eating habits and increased physical activity. The control arm description says parents received instructions in school readiness and performance; the brief description characterizes the control as non-intervention. These descriptions do not fully explain how the control condition was implemented.

The primary outcome was mean change in BMI z-score over three months. The posted arm summaries include 35 participants in the intervention arm and 36 in control for this outcome. The registry says all enrolled participants were analyzed with one exception due to injury and prolonged cast treatment. For participants without a follow-up measurement, the stated intent-to-treat approach filled in data using the experience of control participants who had follow-up measurements.

The registry’s stated aims included assessing recruitment, remeasurement three months after enrollment, and the effect of implementing recommended treatment guidelines. The original design assumptions, detailed allocation procedures, and full protocol 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: After enrollment, the children were randomly assigned to either the intervention or control group. The intervention and control group protocols began on the day of enrollment, immediately after group assignment

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All enrolled were analyzed with one exception (due to injury and prolonged cast treatment). An intent-to-treat analysis required that, for those who did not have the follow-up measurement, data were filled in using the experience of those in the control group who had follow-up measurements.

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: Random allocation resulted in 35 participants in the intervention group and 37 in the control group. However, one participant in the control group was not included in the final analyses due to an interim injury (unrelated to the study) and prolonged cast treatment.

6. Primary Endpoint

The registry lists the primary outcome as Body Mass Index Z-score Change, measured over Three months.

The primary endpoint is change in body mass index z-score over three months, summarized as a mean. BMI relates weight to height; a z-score expresses a measurement relative to a reference distribution. In general, using a z-score can help describe body-size measurements in children across different ages and growth patterns. The registry does not identify the reference standard used to calculate the score, so that detail is not reported in the registry record.

The endpoint focuses on change rather than a single measurement at follow-up. Comparing mean change between groups describes the average difference in the direction and magnitude of movement during the study period. A negative change represents a decrease in the recorded score, while a positive change represents an increase. These averages do not describe every child’s experience, and they do not show how outcomes varied within each group beyond the reported standard errors.

The registry presents the intervention mean change as -0.02 and the control mean change as -0.08. The posted comparison is a mean difference of 0.06, with the intervention estimate minus the control estimate. The clinical importance of a difference of this size is not established by the registry record; it does not report a threshold for a meaningful change.

7. Results Posted in the Registry

• Intervention - Behavioral Counseling: mean -0.02 versus -0.08 on control; difference 0.06 (95% CI -0.08 to 0.20), standardized effect d = 0.20; z-test p = 0.396.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Sugar Sweetened Beverages

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Intervention Group: mean -0.14 versus 0.03 on control; difference -0.17 (95% CI -0.72 to 0.38), standardized effect d = -0.14; z-test p = 0.548.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Group and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary outcome is sugar-sweetened beverages measured in cans per day over three months. Its group comparison has uncertainty spanning values in either direction, rather than a clearly separated contrast. The primary BMI z-score comparison has the same broad pattern: the available estimates do not clearly distinguish a between-group difference from no difference.

At this level, the secondary outcome does not provide a strong independent confirmation or contradiction of the primary result. Both outcomes are continuous measures, and both comparisons are unadjusted in the recalculations. They address different aspects of behavior and body-size change, so similarity in their statistical uncertainty does not mean they measure the same underlying outcome.

Unadjusted secondary findings generally carry less weight than a prespecified primary analysis. When several outcomes are examined, the chance of finding an apparently notable result by chance can increase. In general, multiplicity procedures or a clearly prioritized analysis plan can help address this issue. The registry record does not report such a plan or any adjustment for multiple comparisons.

The outcome description and posted summaries also do not establish whether the secondary measure was selected before results were known, how it was collected, or whether all planned secondary outcomes are represented. The registry lists one posted secondary outcome, but it does not provide enough information to assess the full outcome-selection process. The secondary evidence is therefore best treated as exploratory context, not as a separate definitive test of the intervention.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Sugar Sweetened Beverages

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous, and the registry reports a mean and standard error for each arm. A mean describes the group’s average observed change. A standard error describes the precision of an estimated mean, rather than the spread of individual participant measurements. In general, a standard error tends to be smaller when an estimate is based on more information and the measurements are less variable.

The unadjusted comparison is a difference between the intervention and control means. The reported means are -0.02 and -0.08, respectively, and the posted mean difference is 0.06. This is a descriptive contrast between the groups as reported. It is not an adjusted estimate: the registry record does not specify covariate adjustment for the sponsor analysis.

A confidence interval gives a range of values compatible with the data and the calculation’s assumptions. The recalculated 95% interval for the primary mean difference is -0.079 to 0.199. Since the interval crosses zero, the data do not distinguish the estimated difference from no difference at the conventional two-sided 0.05 significance threshold. The interval also allows differences in either direction. Statistical compatibility is not proof that every value in the interval is equally plausible, nor does it establish clinical importance.

The unadjusted p-value for the primary comparison is 0.396. In general, a p-value is calculated under a null hypothesis and describes the probability of obtaining a result at least as incompatible with that hypothesis as the observed result, if the model assumptions and null hypothesis hold. It is not the probability that the null hypothesis is true, and it is not a measure of effect size. The registry does not report a p-value for the sponsor’s analysis.

The standard errors reported for the arm means are not the standard deviations of individual measurements. A standard deviation describes participant-level variation; a standard error describes uncertainty in an estimated mean. The posted recalculation uses a pooled standard deviation of 0.298 for the primary comparison to express the observed difference in standardized terms. The resulting standardized effect is 0.201. These are unadjusted recalculations from posted summary statistics, not results identified as the sponsor’s primary analysis.

In general, pooling a standard deviation uses information from both groups to represent a common within-group scale. That approach is most straightforward when the groups have comparable variability. The record does not report a diagnostic assessment of this assumption. More broadly, model assumptions matter because confidence intervals and p-values depend on how variation is represented and on the suitability of the approximation used.

The registry lists the reported analysis method as unavailable. It does not describe the sponsor’s model, adjustment variables, treatment of assumptions, or whether the analysis was prespecified. The registry does state that all enrolled participants were analyzed with one exception due to injury and prolonged cast treatment. For participants missing a follow-up measurement, the stated intent-to-treat approach filled in data using the experience of control participants who had follow-up measurements. The precise imputation procedure and its assumptions are not reported in the registry record.

That missing-data approach makes an assumption about what the absent follow-up measurements would have been. In general, replacing missing values using observed outcomes from another group can affect a treatment contrast, and the direction of any effect depends on the pattern of missingness and the imputation rule. The registry does not report sensitivity analyses showing how conclusions change under alternative assumptions.

The study is described as randomized, with a parallel model and single masking. Randomization is intended, in general, to balance measured and unmeasured prognostic factors across groups on average. It does not guarantee balance in a particular small study. The record does not explain who was masked, how allocation was generated or concealed, or whether masking was maintained.

The trial’s original sample-size rationale and statistical plan are not reported in the registry record. Accordingly, the displayed recalculations should not be read as the study’s prespecified analyses. They are unadjusted analyses of posted summaries and are useful for interpreting the scale and uncertainty of the reported contrasts, but they cannot recover unreported design or analysis decisions.

11. Confidence Intervals and Precision

The primary mean difference is 0.06, with a sponsor-reported 95% confidence interval from -0.10 to 0.21. The unadjusted recalculation gives a 95% confidence interval from -0.079 to 0.199. The two intervals differ slightly in their endpoints but both include zero and extend to values in either direction. The sponsor’s own analysis takes precedence over the recalculation when describing the registry’s reported result.

In general, a confidence interval communicates precision by showing the range of estimates compatible with the data under the analysis assumptions. A wider interval indicates greater uncertainty about the magnitude of the contrast. Because the primary interval includes no difference, the point estimate alone should not be treated as a firm indication of which group had the more favorable average change.

The interval also helps distinguish statistical uncertainty from clinical importance. The registry record does not specify a threshold for a clinically meaningful difference, so the interval cannot be classified against such a threshold. Even a statistically distinguishable contrast would not, by itself, establish clinical relevance; conversely, an interval including zero does not prove that the groups are equivalent.

Precision is limited by the amount of information available and by the assumptions behind the analysis. The registry reports standard errors for group means but does not provide participant-level data, a detailed analysis method, or sensitivity analyses for missing follow-up. Those omissions make it difficult to assess how robust the interval is to alternative modeling or missing-data choices. The uncertainty should therefore be read as applying to the posted analysis, rather than as a complete account of all possible sources of uncertainty.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They use the observed effect as a reference and show planning illustrations for detecting the full observed effect, 75% of the observed effect, or 50% of the observed effect. For the primary outcome, the listed figures for 80% power are 388 participants per arm for the full observed effect, 689 for 75% of the observed effect, and 1,549 for 50% of the observed effect. The corresponding figures for 90% power are 519, 922, and 2,073 participants per arm.

In general, a power target is the probability of detecting an effect of a specified size under the assumed design and analysis if that effect is truly present. The 80% and 90% columns therefore describe different planning targets: the 90% target calls for a greater chance of detection under the stated assumptions. Smaller effects require more participants because they are harder to distinguish from random variation.

The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect. The trial’s own original design assumptions are not reported in the registry record. These calculations are planning illustrations based on the observed effect, not observed power.

The sample-size curve should be interpreted as a planning relationship between the assumed effect size and the number of participants needed under those assumptions. It does not describe the number enrolled in the trial as a measure of whether the study succeeded, and it does not show the probability that the posted result is correct.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.060; pooled standard deviation σ = 0.298.
2. n = 2 × (1.96 + 0.842)² × 0.298² / 0.060² = 387.1, rounded up to 388 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.06                      # observed difference in means
sigma <- 0.297939785765562                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1625910)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 388 (80% power), 519 (90% power)
 75% of observed effect: n per arm = 689 (80% power), 922 (90% power)
 50% of observed effect: n per arm = 1,549 (80% power), 2,073 (90% power)
power.t.test: 388 
Simulated power at n = 388 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary analysis as a net mean difference of 0.06, with a 95% confidence interval from -0.10 to 0.21. It does not report a p-value or identify the analysis method. That result is the primary account of the sponsor’s analysis.

The unadjusted recalculation from the posted group summaries also gives a mean difference of 0.06, with a 95% interval from -0.079 to 0.199 and an unadjusted p-value of 0.396. The point estimate agrees, while the interval endpoints differ slightly. These are not conflicting directions of effect; both intervals include no difference and span values on either side of zero.

The recalculation is a simple unadjusted comparison based on the posted summary statistics. It cannot reproduce an analysis method that the registry does not describe, and it should not be treated as a replacement for the sponsor’s result. Since the record does not flag a discrepancy, the two estimates can be described as broadly consistent in their central estimate and overall uncertainty. The sponsor’s own analysis takes precedence when reporting the trial’s analysis.

15. Multiplicity, Missing Data and Analysis Populations

The registry reports a primary outcome and a secondary outcome, but the statistical analysis method and plan for handling multiple comparisons are not reported in the registry record. This matters because testing several outcomes can increase the chance that at least one result appears notable by chance. Without a stated hierarchy or multiplicity adjustment, the secondary comparison should be interpreted cautiously and should not displace the primary outcome.

The missing-data description is more specific than the analysis-method description. The registry says all enrolled participants were analyzed with one exception due to injury and prolonged cast treatment. It also says that, for participants without a follow-up measurement, data were filled in using the experience of control participants who had follow-up measurements as part of an intent-to-treat analysis. The precise imputation algorithm, the number of missing measurements, and the assumptions used are not reported in the registry record.

In general, missing-data methods depend on assumptions about why measurements are absent and what the unobserved values would have been. Using control-group follow-up experience as the basis for filling in missing values can influence the estimated group contrast. Without a reported sensitivity analysis, the robustness of the primary result to alternative missing-data assumptions cannot be assessed.

The registry does not report a detailed definition of the analysis population beyond the statement about all enrolled participants and the exception. It also does not describe protocol deviations, adherence, or whether any analyses differed from the planned approach. The record’s intent-to-treat label should therefore be understood alongside the stated imputation and exception, rather than as a complete account of the analysis population and missing-data handling.

16. 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 registry reports zero serious adverse events among 35 participants at risk in the behavioral-counseling group and zero among 37 at risk in control. It also reports zero other adverse events among those same respective at-risk counts. These figures describe the adverse-event entries posted for the trial.

Zero recorded events does not establish that no adverse events occurred outside the registry’s reporting scope, nor does it demonstrate that the groups have identical safety profiles. In general, when event counts are low or absent, uncertainty about the underlying event frequency can remain substantial. The record does not provide event definitions, surveillance procedures, or a detailed account of how adverse events were collected.

Deaths are not reported in the registry record. The posted zero counts should therefore be read as event counts for the categories explicitly listed, not as a complete statement about every possible safety outcome.

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

The posted results estimate the average change in BMI z-score over three months in each randomized group and the difference between those averages. The point estimate for the primary contrast is 0.06, while the sponsor-reported confidence interval spans values below and above zero. The data therefore leave considerable uncertainty about the direction and size of the between-group difference.

These results do not establish that the groups are equivalent. Demonstrating equivalence would require a prespecified equivalence margin and an analysis designed for that question; neither is reported in the registry record. Nor does an interval that includes no difference establish that there is no effect. It indicates that the posted data do not precisely determine the contrast.

The results also do not establish a clinically meaningful benefit or harm. The registry does not report a threshold for meaningful BMI z-score change. The average group values do not indicate how each participant changed, and the record does not provide enough detail to evaluate individual response patterns.

The trial was framed around feasibility and a low-intensity stage, with aims that included recruitment and follow-up as well as reducing childhood obesity. Numerical feasibility outcomes and detailed recruitment or retention results are not reported in the registry record. The posted outcome estimates are therefore one part of the study’s stated purpose, not a complete assessment of feasibility.

More broadly, this is one completed randomized study with limited posted analysis detail. Its estimates are informative about the observed comparison and its uncertainty, but they do not settle how similar programs would perform in other settings or populations. No medical decision should be based on these registry statistics alone.

18. Why This Trial Matters Statistically

This trial is statistically informative because it illustrates how a randomized comparison can produce a point estimate that is easy to state but remains uncertain. The primary mean difference is 0.06, yet the confidence interval includes no difference and effects in either direction. Reading the estimate together with its interval avoids treating the point estimate as a settled conclusion.

The record also illustrates the difference between a sponsor-reported analysis and a simple unadjusted recalculation. Their central estimates agree, while the reported confidence limits differ slightly. Since the sponsor analysis method is not described, the recalculation cannot explain or replace the sponsor’s result. Transparent reporting of the analysis method would help readers understand why interval estimates differ.

Missing follow-up is another important statistical issue. The registry describes an imputation approach based on control participants with follow-up measurements, but does not give the detailed procedure or sensitivity analyses. Such choices can affect an estimated contrast, especially when the reason for missingness is uncertain. Reporting assumptions and alternative analyses would make the evidence easier to evaluate.

Finally, the planning illustrations show how target sample sizes depend on the effect size a study is designed to detect. The smaller the target effect, the more participants are needed under the stated assumptions. These planning calculations should be kept separate from the trial’s observed results and from any claim about the trial’s original design, which is not reported in the registry record.

19. 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 several trial-specific details unclear. Although it identifies the study as randomized and single-masked, it does not explain the sequence-generation method, allocation concealment, or who was masked. The intervention and control descriptions also differ in emphasis: the brief summary describes a non-intervention control, while the arm description says parents received school-readiness and performance instructions.

The primary outcome description does not identify the BMI z-score reference standard or provide a clinically meaningful change threshold. The registry reports means and standard errors but not participant-level distributions, limiting assessment of skew, outliers, or variation in individual response. The analysis method is not reported, and the sponsor analysis does not include a posted p-value.

Missing follow-up was handled using control participants’ follow-up experience, but the exact imputation procedure, amount of missing data, and sensitivity analyses are not reported in the registry record. The stated exception due to injury and prolonged cast treatment also means the analysis description is not a complete account of all enrolled participants.

The record does not report the original sample-size justification, detailed recruitment and retention results, adherence, or numerical feasibility targets. It also does not describe a multiplicity plan for the secondary outcome. These gaps limit assessment of how the analysis was planned, how representative the posted estimates are of the intended protocol, and how much weight to place on exploratory findings.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: For the Health of Our Children--Clinic Based Treatment of Childhood Obesity — NCT01625910.
• Registry record last updated 2017-03-09; status last verified 2017-01.
• Results first posted 2013-06-06.
• 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.

23. Record Summary

NCT01625910 was a completed randomized, parallel-group study sponsored by the University of Minnesota. It compared behavioral counseling with a control condition for children aged 4 to 8 years described as overweight or obese. The primary outcome was mean change in BMI z-score over three months.

The sponsor-reported primary mean difference was 0.06, with a 95% confidence interval from -0.10 to 0.21. The interval includes no difference and leaves uncertainty about the direction and size of the contrast. A secondary outcome assessed sugar-sweetened beverages over three months.

The registry describes an intent-to-treat approach using control follow-up experience to fill in missing measurements, with one exception due to injury and prolonged cast treatment. Detailed analysis methods, original design assumptions, and a multiplicity plan are not reported in the registry record.