Effect of Infant Formula on Energy Balance: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Infant Formula on Energy Balance (NCT01700205), a randomized na study. The primary outcome is Growth, Weight for Length (WLZ) Z Scores.

2. Clinical Question

3. Trial Design

The registry identifies this as a randomized, triple-masked, parallel trial. Infants were assigned to one of the two formula groups: standard cow milk formula (CMF) or extensively hydrolyzed infant formula (EHF). The arm descriptions say that infants were randomized to feed their assigned formula during the first year of life. The record does not define which people or roles were masked, describe the randomization sequence or allocation concealment, or explain how adherence was assessed.

Enrollment was 113. The primary outcome population is described as an intention-to-treat analysis of 113 infants regardless of study withdrawal. The arm-specific adverse-event records list 59 at risk in CMF and 54 at risk in EHF; these are the group counts reported for those safety outcomes. The record does not provide further detail on the numbers analyzed at each outcome visit.

The trial status is completed. The recorded start date is 2012-11-02 and the primary completion date is 2016-03-17. The phase is listed as NA, and the sponsor is Monell Chemical Senses Center. The primary outcome is continuous and is defined as the mean of a continuous measure. Its timeframe is 0.5 to 12.5 months with followup visit at 18.5 mos. The record also names feeding behaviors and maternal perceptions as secondary outcomes, but does not give their results or enough detail to describe their measurement in depth.

Although the record states the trial was randomized, it does not report the allocation ratio, a sample-size justification, or the planned statistical model. Those details cannot be inferred from the enrollment count or the reported masking and design labels.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: We conducted an intention-to-treat (ITT) analyses on 113 infants regardless of study withdrawal.

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 Growth, Weight for Length (WLZ) Z Scores, measured over 0.5 to 12.5 months with followup visit at 18.5 mos.

The primary endpoint is growth expressed as weight-for-length (WLZ) Z scores. At each visit, infants were weighed and measured, and those anthropometric data were converted using World Health Organization growth standards. The record explains that a Z score expresses an anthropometric value as the number of standard deviations below or above the reference mean. It gives -2.0 to 2.0 as the normal range for this score.

As general background, a standardized score can place an individual measurement in relation to a reference distribution. Weight-for-length relates weight to length, while the Z-score format makes the distance from the reference mean interpretable on a standardized scale. The registry describes the endpoint as a mean, so an arm-level mean would represent the average WLZ score among the infants included in that analysis. The record specifies standard error as the measure of dispersion.

Growth is monitored in the trial through repeated anthropometric assessments, with the stated outcome timeframe extending from 0.5 to 12.5 months and including a followup visit at 18.5 mos. That schedule describes the endpoint's assessment period; it does not by itself establish which time point or summary was used for a single comparison. The registry record does not report the numerical mean scores, their standard errors, or a between-group effect estimate. It therefore does not establish whether the groups differed or how precisely any difference was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as continuous, reports it as a mean, and identifies standard error as the dispersion measure. These labels describe the outcome summary but do not supply the analysis model or the numerical results. The record specifies an intention-to-treat analysis of 113 infants regardless of study withdrawal. The following concepts are general statistical explanations; they are not claims about unreported methods used in this trial.

What does a mean summarize?

For a continuous measure such as a Z score, a mean summarizes the central level of the observations included in an analysis. It can be used to describe each randomized group or, within a specified model, to estimate a contrast between groups. The registry identifies mean WLZ Z scores as the outcome parameter. It does not report the group means, the method for estimating a group contrast, or whether the analysis adjusted for any other variables.

A mean is not a description of every participant's outcome. Individual values can vary around the mean, and a group mean alone does not show the shape or spread of those values. The record's use of standard error addresses uncertainty in estimating the mean; it does not provide a measure of the full variability among infants. No standard deviations or individual-level distributions are reported.

What does standard error convey?

As general statistical background, standard error reflects how much an estimate would vary across repeated samples under a specified sampling and analysis process. Smaller standard errors generally indicate more precise estimates, while larger ones indicate less precision. A standard error is not a clinical threshold and does not, by itself, show whether a difference is important. Here, the registry identifies standard error as the dispersion measure but provides no numerical standard errors for the primary outcome.

Confidence intervals are often used alongside an estimate to express uncertainty. They incorporate an estimate and its standard error under a chosen method and assumptions. Since the registry record reports neither an effect estimate nor an interval for WLZ, the precision of a between-group comparison cannot be evaluated. No interval or test result should be inferred from the enrollment count.

Why does the reference standard matter?

The record says that weight and length were collected at each visit and converted to WLZ Z scores using World Health Organization growth standards. As general background, standardization relates a measurement to a reference distribution, making the score interpretable relative to the reference mean and standard deviation. The record explicitly describes positive and negative Z scores in relation to the reference mean and gives -2.0 to 2.0 as the normal range. These reference-based scores are distinct from raw weight or length measurements; the registry does not report the raw measurements or the exact conversion details.

How should repeated visits be understood?

The timeframe is stated as 0.5 to 12.5 months with followup visit at 18.5 mos. Repeated measurements can describe how an outcome changes over time, but the appropriate statistical approach depends on the study question and the dependence among measurements from the same infant. As general background, repeated observations from the same person are usually not treated as independent observations. The record does not specify whether the analysis used a repeated-measures model, compared selected visits, modeled trajectories, or used another method. Because several time points or categories are present, no single comparison can be selected from the registry description.

What can be inferred from the planning assumptions?

The record describes sample-size planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. These are planning assumptions, not a report of the trial's own design justification. The record does not report a sample-size justification in the trial protocol. Sample-size planning illustrations are not observed power and do not establish whether the primary outcome result is precise. No numerical planning estimates are included in the registry record.

In general, a planning calculation depends on assumptions about the effect size, outcome variability, allocation, statistical test, and desired power. If those assumptions differ from the conditions of a trial, the calculation may not describe the trial's achieved precision. The available registry information does not allow these assumptions to be checked against the actual outcome data.

What is not specified?

The registry record does not report the primary outcome estimates or the analysis model, nor does it describe covariate adjustment, handling of repeated observations, or treatment of outliers. It also does not report confidence intervals or primary outcome test statistics. These omissions prevent a detailed appraisal of the statistical analysis and its uncertainty. The randomized design and the outcome definition remain informative, but they cannot replace the missing result and analysis details.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is measured across several categories or time points, and the registry description does not reduce it to a single comparison. The stated timeframe is 0.5 to 12.5 months with followup visit at 18.5 mos. The record lists eight outcome measures and seven analyses, and names feeding behaviors and maternal perceptions as secondary outcomes. These features mean that the registry description includes multiple potential outcomes or assessments, but it does not specify which comparisons were designated as primary for inference.

As general background, making many statistical comparisons can increase the chance of a seemingly notable result arising by chance. Researchers may address that issue through a prespecified testing hierarchy, adjustment, or a clearly defined primary comparison. The registry record does not report whether multiplicity was addressed, whether any adjustment was used, or how the outcome time points were handled. No correction method should be assumed.

The primary outcome population is described as an intention-to-treat analysis of 113 infants regardless of study withdrawal. In general, intention-to-treat refers to analyzing participants according to randomized assignment, regardless of later adherence or withdrawal, in keeping with a defined analysis plan. The registry does not explain how missing outcome observations were handled, whether outcomes were available at every visit, or whether imputation or another missing-data method was used. Thus, the stated population does not establish that every infant contributed a measurement at every assessment.

The registry also does not report a per-protocol or other analysis population, or sensitivity analyses addressing missing data. Without those details and the numerical outcome results, it is not possible to assess how missing observations or multiple assessments affected the reported inference.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event entries list 59 infants at risk in CMF and 54 at risk in EHF. For serious adverse events, the recorded number affected is zero in each group. For other adverse events, the recorded number affected is also zero in each group. The death count is zero in both groups. These are registry counts for the groups and categories as recorded; they are not rates or comparative estimates.

As general background, an “at risk” count identifies the group represented in an adverse-event record, while an “affected” count records those entered as having the event category. A zero count means no events were recorded in that category for the listed group. It does not, on its own, establish that no event of any kind occurred or that the groups have identical safety profiles.

The record does not describe the adverse-event definitions, collection period, severity criteria, event attribution, or completeness of reporting. It also gives no event-level descriptions. Accordingly, the counts should be read narrowly as the serious and other adverse-event figures posted for these arms, rather than as a complete assessment of safety or a basis for comparing risks.

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

The trial record describes a randomized comparison of standard cow milk formula and extensively hydrolyzed infant formula, with growth assessed using WLZ Z scores. It identifies a triple-masked parallel design and an intention-to-treat analysis population of 113 infants regardless of study withdrawal. These details establish the central design and outcome framework, but the record does not include the numerical primary outcome findings.

For that reason, the record does not establish whether mean WLZ differed between the groups, whether any estimated difference favored either group, or how precise a comparison might be. There is no reported effect estimate, confidence interval, or test result for the primary outcome. A lack of reported results cannot be interpreted as no effect, and it cannot be interpreted as evidence of an effect.

The endpoint is a reference-based growth measure derived from weight and length, assessed over the stated timeframe. It is not, by itself, a complete description of all aspects of growth, feeding behavior, or energy balance. The study's brief summary describes a broader research aim involving physiological and behavioral mechanisms, but the record's primary outcome definition does not establish findings for every part of that broader aim. Feeding behaviors and maternal perceptions are named as secondary outcomes, without numerical findings.

The posted adverse-event counts are zero for serious events, other events, and deaths in both formula groups. Those entries should be understood as reported counts, not as proof that no adverse experiences occurred or that the groups are equivalent in safety. Details on event definitions and collection are not reported in the registry record.

Therefore, the defensible interpretation is limited: the registry documents the trial design, formula assignments, primary outcome definition, analysis population, and posted safety counts. It does not report enough outcome information to quantify or characterize the primary comparison. No conclusion about the effects of either formula on growth can be drawn from the registry record alone.

13. Why This Trial Matters Statistically

This trial is statistically informative in its design description because it identifies random assignment, masking, parallel groups, and a continuous growth outcome. Those features help readers understand how the comparison was structured and what the investigators intended to measure. The stated intention-to-treat population also clarifies that the primary analysis was described as including infants regardless of study withdrawal.

The record also illustrates why an outcome definition is not the same as an outcome result. It explains how WLZ scores were derived from weight and length using World Health Organization growth standards, gives the assessment timeframe, and specifies mean and standard error as the outcome summary. Yet the record does not report the actual means or an estimate of the difference between formula groups. Without those values, neither magnitude nor precision can be assessed.

Repeated assessments raise important statistical questions about the choice of comparison, dependence among observations, and handling of missing measurements. The registry record does not specify the model or the approach to multiplicity. Those omissions matter because the outcome timeframe includes several assessment points and the registry identifies multiple outcome measures and analyses. The listed counts alone do not reveal which comparisons drove the investigators' conclusions.

The safety entries offer a separate, limited illustration: event counts are reported by group, but the collection and classification methods are not described. The figures can be read as posted counts without being expanded into claims about comparative safety.

Overall, the record is useful for understanding the trial's framework and the limits of what can be concluded from its registry information. It also demonstrates that randomization and a prespecified-sounding endpoint do not provide the missing results or analytical detail. Clear reporting of estimates, uncertainty, analysis methods, and missing-data handling is necessary for readers to evaluate the evidence.

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 main limitation for interpreting this trial from the registry record is that numerical primary outcome results are not reported. The record gives the WLZ outcome definition, timeframe, analysis population, and summary type, but it does not provide group means, a between-group estimate, uncertainty intervals, or test results. Thus the central comparison cannot be quantified or interpreted for direction.

The endpoint has several categories or time points and is not reduced to a single comparison. The registry does not specify how those observations were combined or analyzed, or whether a particular visit was the principal comparison. It also does not report a statistical model, adjustment variables, or a method for accounting for repeated measurements. These gaps limit assessment of the analysis strategy.

The registry describes an intention-to-treat analysis of 113 infants regardless of withdrawal, but does not report visit-specific numbers analyzed, the amount or pattern of missing data, or the method used to handle missing observations. The stated analysis population therefore does not show whether outcome data were available throughout the assessment period or how incomplete records affected estimates.

Although the record lists eight outcome measures and seven analyses, it does not explain which outcomes or comparisons were treated as primary for statistical testing, or whether multiplicity was addressed. It names feeding behaviors and maternal perceptions as secondary outcomes without reporting their results. The sample-size planning assumptions are described as planning illustrations, but the record does not provide the trial's own sample-size justification.

Finally, the adverse-event entries are counts without definitions, collection procedures, or event-level descriptions. The registry record does not report enough information to assess completeness or make a comparative safety inference. These limitations concern what the record reports; they do not establish that the trial did not collect additional information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effect of Infant Formula on Energy Balance — NCT01700205.
• Registry record last updated 2019-11-22; status last verified 2019-11.
• Results first posted 2019-09-16.
• 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

NCT01700205, titled “Effect of Infant Formula on Energy Balance,” is listed as a completed randomized, triple-masked, parallel trial sponsored by Monell Chemical Senses Center. Enrollment was 113. The recorded start date is 2012-11-02, and the primary completion date is 2016-03-17. The phase is listed as NA.

The trial compared standard cow milk formula (CMF) with extensively hydrolyzed infant formula (EHF). Its primary outcome was mean weight-for-length Z score, derived from anthropometric measurements using World Health Organization growth standards. The timeframe was 0.5 to 12.5 months with followup visit at 18.5 mos. The primary population is described as an intention-to-treat analysis of 113 infants regardless of study withdrawal.

Feeding behaviors and maternal perceptions are listed as secondary outcomes. Serious and other adverse-event counts and deaths are recorded as zero in both groups. Numerical primary outcome results, the analysis model, multiplicity handling, and missing-data methods are not reported in the registry record.