Hydration Factor Study for the Stayhealthy BC3: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hydration Factor Study for the Stayhealthy BC3 (NCT01209936), a na na study. The primary outcome is Estimated Body Fat % for Children Aged 10-17 Years Old.

2. Clinical Question

3. Trial Design

The registry identifies this as a completed pilot study, with a single-group model and enrollment of 360. The recorded study start is 2009-09 and primary completion is 2010-06. The study phase is listed as NA. Allocation is also listed as NA, and masking is recorded as NONE. These entries do not describe a randomized, masked, controlled comparison. The registry specifically cautions that the arms are not a like-for-like control comparison.

The sponsor is the University of Southern California. Body Composition is the listed condition. The intervention entry names D2O and classifies it as a device. The arm description says total body water measured on the BC3 was compared with total body water measured by deuterium oxide. This is consistent with the broad validation purpose in the brief summary, which concerns whether the BC3 hydration factor represents hydration status compared with total body water assessed by D20.

The record also describes adult and children groups in its safety information. It does not provide a detailed account of how participants were assigned to those groups, whether every enrolled participant received the same assessments, or how many contributed data to each endpoint analysis. The group descriptions alone should not be interpreted as evidence of randomized treatment allocation or as evidence that one group served as a control for the other.

There is an important difference between the broad study objective and the named primary endpoint. The primary endpoint is estimated body fat percentage for children aged 10-17 years old, and its description says the BC3 was analyzed against hydrostatic weighing. That is distinct from the stated hydration-factor objective and the arm description's comparison of total body water against deuterium oxide. The registry does not explain the relationship between these descriptions.

The registry lists 3 outcome measures and 3 analyses. The details needed to understand the full analysis plan, including analysis populations and the handling of missing measurements, are not reported in the registry record. The entry also does not report a protocol-level sample-size justification or a statistical plan for the trial's own design.

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 Estimated Body Fat % for Children Aged 10-17 Years Old, measured over One time point (only one day visit).

The named primary endpoint is estimated body fat percentage for children aged 10-17 years old. It is a continuous measurement, expressed in percent body fat, and the registry identifies the summary measure as a mean with standard deviation. The timeframe is one time point, described as only one day visit. Its description says the Stayhealthy BC3 was analyzed against hydrostatic weighing for children in this age range.

In general, body fat percentage is a quantitative measure that can be compared across measurement methods. A comparison with a reference method can help assess whether measurements from a device correspond to those from the stated comparator. The mean describes the central value in a group, while the standard deviation describes how dispersed individual measurements are around that mean. These summaries do not, by themselves, establish agreement between methods; interpretation also depends on the numerical results and on the analysis used to evaluate the relationship or differences.

The registry does not report the primary endpoint's mean, standard deviation, sample size for the endpoint analysis, or an estimate of agreement or difference. It therefore does not allow a reader to assess the observed body-fat measurements or their precision. Also, this endpoint is body fat percentage, whereas the brief study summary emphasizes hydration status and total body water. The record does not explain how the primary endpoint supports the stated hydration-factor validation objective.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean with standard deviation describe?

The primary endpoint is identified as a continuous measure, summarized as a mean and standard deviation. In general, a mean is the arithmetic average of measured values and provides a measure of their central location. A standard deviation describes the spread of individual observations around that mean. The mean and standard deviation answer different questions: the first concerns the average level, while the second concerns how variable measurements are among the people assessed.

These summaries are useful for describing a continuous outcome, but they do not fully describe all aspects of a distribution. They do not, on their own, show whether two measurement methods agree for individual participants. For a device-validation question, the analysis would need to match the intended claim: a relationship between measurements, systematic differences, or agreement are distinct statistical questions. The registry's primary endpoint metadata do not specify such an analysis, and numerical endpoint results are not reported in the registry record.

What would a comparison with a reference method mean?

In general, a reference-method comparison evaluates measurements from a device alongside measurements from another method. The interpretation depends on the question and statistical method. Correlation describes whether values tend to vary together, but a high correlation does not necessarily mean that two methods give similar values. Agreement analyses instead focus on how close paired measurements are and whether any discrepancy changes across the measurement range. These general distinctions matter because the record uses validation language, yet does not report the numerical comparisons or specify the analysis used to assess them.

For this study, the registry has more than one description of the relevant comparator. The primary endpoint text names hydrostatic weighing for the body-fat outcome in children aged 10-17 years old. The brief summary and arm description instead discuss total body water and deuterium oxide. The record does not explain whether these descriptions refer to separate objectives, how their analyses were related, or which comparison formed the principal validation analysis.

Why does the design description matter?

The record identifies a single-group model, allocation as NA, and masking as NONE. It also says the arms are not a like-for-like control comparison. In general, these design features affect which comparisons can be interpreted and what kinds of conclusions are justified. A comparison of two measurement methods within a study is not the same as a randomized comparison of treatments. The adult and children safety groups do not establish a treatment-control contrast, and the registry does not describe random assignment.

Because the entry does not report the detailed protocol or analysis plan, it is not possible to determine from the registry how measurement order, paired observations, repeated values, or other design details were handled. Such details can be relevant to precision and interpretation in a method-comparison study. They should not be inferred from the brief descriptions.

How should uncertainty be understood?

In general, an estimate is more informative when accompanied by a measure of uncertainty. A confidence interval communicates the range of values compatible with the observed data under a specified statistical procedure and its assumptions. Its width depends on factors including sample size, variability, and the method used. A p-value, when used, measures how unusual data at least as extreme as those observed would be under a specified null hypothesis; it is not a measure of the size or clinical importance of an effect.

The registry record does not report a primary endpoint estimate, confidence interval, or p-value. It also does not report the endpoint's analyzed sample size or standard deviation. Therefore, the precision of the primary endpoint cannot be judged from the registry. The record's stated endpoint summary type does not substitute for the actual numerical estimate and uncertainty.

What does the planning illustration represent?

The stated sample-size assumptions describe a planning illustration computed from the observed effect, rather than the trial's own design. The assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect expressed as a stated fraction of the observed effect. For time-to-event tables, the stated output would be the total number of events using the Schoenfeld method; for other outcomes, it would be participants per arm.

In general, such calculations ask how much information a hypothetical future comparison might require under chosen assumptions. They are sensitive to the assumed effect size, variability, significance level, allocation, and analysis. The resulting participant counts, when displayed, are planning illustrations only. They are not the number of participants actually analyzed, do not describe the trial's original sample-size rationale, and must not be interpreted as observed power. The registry does not report the study's own sample-size justification or its original statistical design assumptions.

Why can over-dispersion matter?

In general, over-dispersion occurs when count data vary more than a statistical model assumes. If a model underestimates that variability, standard errors can be too small and intervals too narrow. The primary endpoint in this record is continuous rather than a count outcome, and the registry does not identify a count-based primary analysis. Over-dispersion therefore cannot be assumed to be relevant to the primary endpoint. The appropriate statistical model and its assumptions are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 3 analyses. When a study evaluates multiple outcomes or performs multiple analyses, the chance of a false-positive finding across the set can increase if each result is interpreted independently. In general, multiplicity procedures can address that issue by adjusting significance thresholds or otherwise controlling error across a defined family of tests. The choice depends on the study questions and analysis plan.

The record does not report whether any multiplicity adjustment was planned or used, how outcomes were ordered, or which analyses were considered confirmatory. The existence of several listed outcomes and analyses does not by itself show that an adjustment was required or that one was applied. No endpoint-specific p-values are reported in the registry record, so the impact of multiplicity on the reported evidence cannot be assessed.

The registry also does not describe missing-data methods, the number of missing measurements, or the analysis populations. It does not identify whether the primary endpoint analysis included all enrolled participants, only participants with paired measurements, or another group. These details matter because exclusions and missing measurements can affect both the estimated result and its precision. They should not be inferred from the enrollment figure or from the safety-group counts.

For a method-comparison study, paired measurement availability may be important because evaluating methods generally requires results from both methods for the same participant. The registry does not report how many paired observations were available or how incomplete pairs were handled. The analysis plan, missingness assumptions, and any sensitivity analyses are not reported in the registry record.

11. 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 lists 0 serious affected participants among 245 at risk in the Deuterium Oxide and BC3 Adult group. It lists 0 serious affected participants among 117 at risk in the Deuterium Oxide and BC3 Children group. These are the reported counts for the serious adverse event category in those groups.

A count of 0 serious affected participants does not mean that no adverse events of any kind occurred. The record does not provide a list of serious-event terms, and no top serious terms are listed. It also does not give the event observation period or a detailed description of how serious events were defined or collected. Death counts are not reported in the registry record; the death entries are null rather than numerical counts.

The at-risk counts in the safety groups should be read as group-specific figures, not as a randomized comparison. The registry identifies a single-group model and says the arms are not a like-for-like control comparison. It does not explain how the group at-risk counts relate to the recorded enrollment of 360. Without additional safety details, the figures do not support a broader conclusion about the frequency of all adverse events or a comparison of risk between groups.

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

The record identifies a completed pilot study intended to validate the BC3 hydration factor, with a stated focus on whether that value represents hydration status compared with total body water assessed by D20. It also identifies a primary endpoint of estimated body fat percentage in children aged 10-17 years old, described as BC3 analysis against hydrostatic weighing. These are the stated aims and endpoint descriptions; the registry does not report numerical results that show how either comparison performed.

Without an endpoint estimate, standard deviation, confidence interval, or other reported comparison result, readers cannot assess the size of any observed difference, relationship, or agreement. The record therefore does not support a quantitative conclusion about the BC3's measurement performance. It also does not provide enough detail to determine whether the body-fat endpoint was intended as a direct test of the hydration-factor objective or as a distinct analysis.

The single-group design and absence of a like-for-like control comparison mean that the adult and children group labels should not be interpreted as randomized arms. The record's safety counts can be described as reported, but they do not establish that no adverse events occurred beyond the serious affected-participant counts shown, nor do they provide a basis for comparing safety between randomized treatments.

In general, a pilot study can inform the feasibility and planning of later research, but its value depends on the measurements, analyses, and results reported. Here, the registry describes the study's purpose, endpoint type, and broad design while leaving key result and analysis details unreported. The appropriate interpretation is limited to those details. No claim about a treatment effect, validity, or clinical benefit can be made from the registry information available.

13. Why This Trial Matters Statistically

This study raises several statistical issues that are common in device-validation research. The question is not simply whether two measurements are associated; it may also concern whether they agree closely enough for the intended use. In general, association, systematic bias, and individual-level agreement are different properties, and they require an analysis aligned with the validation question. The registry describes a hydration-factor objective and a comparison of total body water measurements, but does not report the analysis or numerical results needed to assess those properties.

The distinction between the broad objective and the primary endpoint is also important. The brief summary describes hydration status and total body water, while the primary endpoint is estimated body fat percentage in children aged 10-17 years old, described against hydrostatic weighing. Clear alignment among the objective, endpoint, comparator, and analysis is important for interpreting evidence. The registry does not explain how these elements fit together.

The design information reinforces the need for careful interpretation. A single-group study with allocation listed as NA and masking listed as NONE is not a randomized treatment comparison. The registry explicitly cautions that its arms are not like-for-like controls. Thus, the group labels should not be read as evidence of comparative treatment allocation.

Finally, statistical conclusions require estimates and uncertainty, not only endpoint names and design labels. The absence of reported numerical primary results prevents assessment of effect size and precision. Missing analysis-population and missing-data details further limit reproducibility and interpretation. These gaps make the registry record useful for understanding the intended study question, but insufficient for assessing the quantitative evidence for validation.

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 has a mismatch between the stated broad study purpose and the primary endpoint description. The brief summary focuses on validating the BC3 hydration factor against total body water assessed by D20, and the arm description names deuterium oxide as the comparator for total body water. The primary endpoint, however, is estimated body fat percentage in children aged 10-17 years old, described as BC3 analysis against hydrostatic weighing. The record does not reconcile these descriptions, so the specific relationship between the primary outcome and the stated validation objective remains unclear.

Numerical results for the primary endpoint are not reported in the registry record. The endpoint's mean, standard deviation, analyzed sample size, and method-comparison estimate are unavailable. The registry also does not report confidence intervals or p-values for the primary endpoint. This prevents evaluation of the direction, magnitude, and precision of the reported outcome.

The design description is limited. Although the model is single-group, allocation is NA, and masking is NONE, the record does not provide a full account of participant flow, measurement procedures, or analysis populations. It does not explain the relation between enrollment of 360 and the adult and children safety-group counts. The statistical plan, handling of missing measurements, and any sensitivity analyses are not reported in the registry record.

The record lists 3 outcome measures and 3 analyses but does not state how multiplicity was addressed. It also does not provide enough safety information to interpret the 0 serious affected participants as a complete account of adverse events. The serious-event observation period and death counts are not reported in the registry record. These limitations restrict both evaluation of measurement performance and interpretation of the safety information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Hydration Factor Study for the Stayhealthy BC3 — NCT01209936.
• Registry record last updated 2023-12-11; status last verified 2023-12.
• Results first posted 2023-12-11.
• 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

The registry describes a completed pilot study sponsored by the University of Southern California, with a recorded start of 2009-09, primary completion of 2010-06, and enrollment of 360. It lists Body Composition as the condition, D2O as the intervention, a single-group model, allocation as NA, and masking as NONE.

The broad purpose is to validate the BC3 hydration factor against total body water assessed by D20. The primary endpoint is estimated body fat percentage for children aged 10-17 years old, summarized as a mean with standard deviation at one time point; its description names hydrostatic weighing as the comparator. Numerical primary results and the analysis details needed to interpret them are not reported in the registry record.

The safety entry reports 0 serious affected participants among 245 at risk in the adult group and 0 among 117 at risk in the children group. Death counts are not reported in the registry record. The record lists 3 outcome measures and 3 analyses but does not describe multiplicity handling, missing-data methods, or analysis populations.