Activity, Adiposity, and Appetite in Adolescents 2: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Activity, Adiposity, and Appetite in Adolescents 2 (NCT04028921), a registered phase not stated study. The primary outcome is Appetite- Subjective.

2. Clinical Question

The activity categories use a threshold of at least 60 min/day of moderate/vigorous physical activity for the active groups and less than 60 min/day for the sedentary groups. The normal-weight groups are described as having BMI percentile at least 5th and less than 75th for age/sex; the overweight/obese groups are described as having BMI percentile at least 85th and less than 99th for age/sex.

3. Trial Design

Despite its registry classification as a clinical study, this is not a randomized intervention trial. The study description identifies a cross-sectional design in which adolescents are classified by bodyweight and physical activity, and the intervention field lists “No intervention.” The four listed groups combine two bodyweight categories with two activity categories. Participants are not assigned to increase or decrease activity or to receive a treatment.

The planned population comprises male and female adolescents aged 14–17 years. The registry record lists an enrollment of 46. Its dates are 2022-01-03 for study start and 2023-11-01 for primary completion, and its status is COMPLETED. These administrative details do not establish how many participants contributed data to each endpoint or whether all enrolled participants completed every measurement.

The study goal is to examine links among physical activity, appetite control, and energy metabolism. The listed primary measure is subjective appetite, specifically hunger area under the curve following a fixed-calorie meal, assessed at baseline. The record lists three outcome measures but gives detail for the primary measure only. The number of analyses listed is zero, and outcome estimates are not reported in the registry record.

Because the groups are observational and differ by both bodyweight category and activity, group contrasts cannot be interpreted as the effect of assigning a particular activity level or bodyweight category. The record itself notes that the arms are not a like-for-like control comparison. Methods for recruitment, measurement of activity beyond the listed category definitions, adjustment for potential confounding, and handling of repeated measurements 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.

Overall Study

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 Appetite- Subjective, measured over Baseline.

The primary endpoint is “Appetite- Subjective,” measured as hunger area under the curve (AUC) after a fixed-calorie meal. Hunger and palatability are assessed with self-rated visual analogue scales. The described hunger scale runs from 0, “I am not hungry at all,” to 100, “I have never been more hungry.” The endpoint’s unit is score on a scale*min, and the specified summary is the mean with standard deviation at baseline.

A visual analogue scale is a way to record a participant’s subjective rating along a defined range. It can capture the intensity of an experience that is not directly measured by a physical instrument. Here, the scale concerns hunger, so the result represents a participant-reported response rather than an objective measure of energy intake or metabolic function.

AUC combines responses over the measurement period into one summary. The registry description says it is calculated by approximating the area under the response curve as a trapezoid. In general, this type of summary can represent both the level and pattern of ratings over the observation period, but its interpretation depends on the timing and number of measurements. Those details, as well as the observed AUC values and their variability, are not reported in the registry record.

The registry record specifies a mean and standard deviation as the endpoint summary, but it does not report the mean, standard deviation, participant counts contributing to the endpoint, or a comparison between groups. The endpoint therefore identifies what was intended to be measured, not what the observed appetite data show.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods that can be described from the registry record are limited. It identifies a cross-sectional study, four observational groups, a continuous primary endpoint, and a mean with standard deviation as the endpoint summary. The record does not report an inferential statistical plan. The explanations below describe general statistical concepts; they do not imply that a particular method was used in this study.

What does a cross-sectional comparison estimate?

In general, a cross-sectional study measures characteristics within a defined study period and examines how they vary together. Group comparisons can describe observed differences, but they do not by themselves show that one characteristic caused another. This distinction is especially important when participants are classified by existing activity and bodyweight rather than randomly assigned to those categories. Other characteristics may differ between groups and could contribute to an observed association. Adjustment methods can sometimes address measured differences, but the variables collected and any adjustment strategy are not reported in the registry record.

What do mean and standard deviation describe?

In general, the mean is a measure of the central level of a continuous outcome, while the standard deviation describes how spread out individual observations are around that mean. They answer different questions: the mean describes the average observed score, and the standard deviation describes participant-to-participant variability. A mean and standard deviation alone do not establish whether groups differ. A comparison also needs an estimate of the contrast and information about its uncertainty. The registry record does not report observed means or standard deviations for the primary endpoint.

What does a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimate using a range of values compatible with the data under the method’s assumptions. A narrow interval indicates greater precision than a wide interval, though interpretation also depends on the outcome scale and study design. A confidence interval is not reported for the primary endpoint in the registry record. Without an estimate and an interval, the magnitude and precision of any group contrast cannot be assessed.

How should AUC be understood?

The registry description says appetite AUC is calculated using the area of the response as for a trapezoid. In general, trapezoidal integration approximates the area between measurement points by treating each segment as a trapezoid and combining the segment areas. The resulting AUC reflects ratings across the observation period, rather than a single rating at one moment. Because the scale is a rating and the endpoint unit is score on a scale*min, interpretation depends on the timing of assessments and the length of the observation period. Assessment timing and the observed AUC values are not reported in the registry record.

Why do group definitions affect analysis?

The four groups distinguish bodyweight category and activity category. This structure permits descriptive examination of patterns across those categories, but it does not make any one group a randomized control group. General statistical analysis could compare group means, model activity and bodyweight categories, or account for other measured characteristics. Which approach would be appropriate depends on the research question, data structure, and prespecified plan. The analysis method, model terms, assumptions, and any covariate adjustment are not reported in the registry record, so no specific analytical approach should be attributed to this study.

What do the planning assumptions mean?

The registry’s methodological note describes planning illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. In general, such illustrations show how an assumed target effect and statistical assumptions relate to a prospective sample-size target. They are not observed results, and they are not observed power. The note also distinguishes illustrations giving participants per arm from time-to-event illustrations giving total events. The record does not report the observed endpoint effect needed to assess such an illustration, nor does it report a trial-specific sample-size justification.

General statistical interpretation also depends on data quality, endpoint completeness, and whether the analysis follows a prespecified plan. Those details are not reported in the registry record. Thus, the available method description is enough to identify the type of endpoint and broad design, but not enough to reconstruct or evaluate an analysis.

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("Normal Weight, Active", "Normal Weight, Sedentary", "Overweight/Obese, Active", "Overweight/Obese, Sedentary")
n   <- c(13, 11, 12, 10)
m   <- c(9239.4, 7879.6, 6130.5, 8970)
sp  <- c(3635.1, 5343.5, 4279.7, 3664.9)
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  Normal Weight, Active  13  9239.400  3635.100  7042.731  11436.069
CARM  Normal Weight, Sedentary  11  7879.600  5343.500  4289.788  11469.412
CARM  Overweight/Obese, Active  12  6130.500  4279.700  3411.308  8849.692
CARM  Overweight/Obese, Sedentary  10  8970.000  3664.900  6348.288  11591.712

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures, but gives a detailed description only for the primary subjective appetite endpoint. Names and definitions for the other outcome measures are not reported in the registry record. The number of analyses listed is zero, and no outcome analysis results are reported.

Multiplicity arises when several outcomes, groups, time points, or statistical tests are examined. In general, testing many hypotheses can increase the chance of finding an apparently notable result by chance. Researchers may address this through a prespecified hierarchy of outcomes, adjusted significance thresholds, or other methods. The record does not report whether any multiplicity strategy was planned or used, so it is not possible to determine how multiple outcomes or comparisons were handled.

Missing-data handling is also not reported in the registry record. The total enrollment is 46, but the number of participants contributing to the primary endpoint or to each group is not reported. The record does not explain whether any measurements were incomplete, how missing observations were treated, or whether sensitivity analyses were performed. Enrollment therefore should not be assumed to equal the analysis population.

Analysis populations are not described. For an observational study, the relevant population might be defined by eligibility, completed measurements, or another criterion, but the registry record does not state which participants were included in any analysis. It also does not report exclusions after enrollment or reasons for missing endpoint data. These omissions limit assessment of potential selection bias and the applicability of any result; in this record, outcome estimates themselves are also absent.

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.

Most frequent non-serious adverse event terms

The safety record reports serious adverse events separately for the four observational groups. It lists 0 affected among 13 at risk in Normal Weight, Active; 0 affected among 11 at risk in Normal Weight, Sedentary; 0 affected among 12 at risk in Overweight/Obese, Active; and 0 affected among 10 at risk in Overweight/Obese, Sedentary. Deaths are listed as 0 in each group. No serious adverse-event terms are listed.

For other adverse events, the record lists 2 affected among 13 at risk in Normal Weight, Active; 2 among 11 in Normal Weight, Sedentary; 2 among 12 in Overweight/Obese, Active; and 1 among 10 in Overweight/Obese, Sedentary. These are counts of affected participants and participants at risk as recorded for each group; they are not comparisons adjusted for group characteristics.

In general, a zero count in a study record means no events are listed for that category and group in the posted safety data. It does not establish that the underlying risk is zero. The record does not describe event definitions, collection procedures, severity breakdowns for other adverse events, or the observation period for safety reporting. Because this study lists no intervention and is observational, these figures should not be interpreted as a comparison of treatment safety.

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

The record identifies a completed cross-sectional study of adolescents grouped by bodyweight and activity, with subjective hunger AUC after a fixed-calorie meal as the primary endpoint. It also gives the endpoint scale description, summary measure, and safety counts. These details clarify what the study was designed to examine and how the primary appetite measure was defined.

However, the registry record does not report the primary outcome values or statistical analysis results. There is therefore no basis in the posted results for describing the direction or size of any appetite difference, estimating its precision, or stating whether a statistical test supported a group contrast. The absence of results is not evidence that there was no association or no difference.

Even if group estimates were available, the cross-sectional, non-randomized design would require cautious interpretation. The groups are defined by both bodyweight and activity, and the record explicitly says they are not a like-for-like control comparison. An observed association would not establish that activity caused a change in appetite, that appetite caused a difference in activity, or that either characteristic caused a difference in bodyweight. Other measured or unmeasured characteristics could contribute.

The appetite endpoint is based on participants’ self-rated hunger and summarizes ratings across time. It does not directly measure food intake, metabolic function, or a clinical outcome. The registry describes the wider goal as examining appetite control and energy metabolism, but the detailed results needed to assess those relationships are not reported.

The safety figures are descriptive counts for the groups. They do not establish comparative risk, particularly in the absence of an intervention and additional information about event definitions and observation. The enrollment and completed status likewise do not show how many participants contributed to each endpoint.

In short, the record permits a design-level and measurement-level account, but it does not permit a conclusion about the study’s findings. Any claim about a relationship among activity, bodyweight, hunger, or metabolism would require outcome estimates and analysis details not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why a registry description and a statistical result are different kinds of evidence. The record can define a research question, identify an endpoint, specify group categories, and state the intended summary measure. Those details are useful for understanding what investigators planned to measure. They do not show what the observed data were or how strongly the data support a comparison.

It also highlights the importance of design when interpreting group differences. Participants are categorized by bodyweight and activity rather than assigned to an intervention. Such comparisons can be informative about patterns in the observed population, but they are not randomized estimates of an activity intervention’s effect. A clear statement of the comparison and its limitations helps prevent descriptive associations from being mistaken for causal conclusions.

The endpoint itself raises practical statistical questions. Subjective appetite ratings are measured on a defined visual scale, then summarized over time as AUC. That summary can be useful when the pattern over a period matters, but it depends on measurement timing and the way the response curve is summarized. Reporting the observed group estimates, variability, uncertainty, and assessment details would make the endpoint easier to interpret and evaluate.

Finally, the record demonstrates the importance of transparent reporting beyond a primary endpoint label. Information about the other listed outcomes, analysis populations, missing data, multiplicity, and statistical methods would help readers assess how complete and robust the evidence is. These details are not reported in the registry record. Here, the statistical lesson is not a claim about the outcome; it is the need to distinguish what was measured from what can be concluded.

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 main limitation for interpreting this study record is that outcome estimates and analysis results are not reported. The primary endpoint is described, but its mean, standard deviation, group-specific values, and uncertainty are absent. The record lists zero analyses, so the size and precision of any observed pattern cannot be assessed.

The design is cross-sectional and observational, with groups defined by bodyweight and activity. The record cautions that these groups are not a like-for-like control comparison. Consequently, group contrasts would not by themselves establish causal effects, and the registry record does not report methods for adjustment for potential confounding.

Although three outcome measures are listed, detailed definitions are not reported for the other two. Measurement timing for the appetite ratings, endpoint completeness, missing-data procedures, analysis populations, and methods for handling multiple outcomes or comparisons are also not reported in the registry record. Without these details, readers cannot evaluate how the analysis population was formed or whether analytic choices may affect interpretation.

The registry lists enrollment of 46, but group-specific numbers contributing to the primary endpoint are not reported. This prevents assessment of endpoint-specific data availability and precision. The planning note describes general assumptions for sample-size illustrations, but a trial-specific sample-size justification is not reported in the registry record.

Safety information is limited to the recorded counts. Event definitions, collection procedures, and observation details are not reported. These limitations concern what can be learned from the registry record; they do not establish that the study data or analyses were inadequate.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Activity, Adiposity, and Appetite in Adolescents 2 — NCT04028921.
• Registry record last updated 2025-04-02; status last verified 2025-03.
• Results first posted 2025-04-02.
• 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

NCT04028921, titled “Activity, Adiposity, and Appetite in Adolescents 2,” is listed as COMPLETED. The sponsor is Children's Mercy Hospital Kansas City. The record gives a study start of 2022-01-03, primary completion of 2023-11-01, and enrollment of 46.

The study is described as cross-sectional and lists no intervention. Male and female adolescents aged 14–17 years are grouped by BMI percentile and moderate/vigorous physical activity. The primary endpoint is subjective hunger AUC after a fixed-calorie meal, assessed at baseline with visual analogue scales and summarized as a mean with standard deviation.

Three outcome measures are listed, but detailed results and analyses are not reported in the registry record. Serious adverse events and deaths are listed as 0 in each group; other adverse-event counts are also recorded by group. The posted record therefore describes the design and measurement but does not provide estimates with which to assess the primary research question.