FitEx for Endometrial Cancer Survivors: Initial Efficacy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for FitEx for Endometrial Cancer Survivors: Initial Efficacy (NCT05737745), a randomized na study. The primary outcome is Moderate to Vigorous Physical Activity of Endometrial Cancer Survivors.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group pilot trial with no masking reported. The registry record lists the study as completed and gives an enrollment of 111. Participants were assigned to usual care, FitEx-ECS, or FitEx-ECS+ Yoga. The intervention programs involved survivors and support team members; the usual-care group received standard survivorship care, an educational newsletter, and a Fitbit. The record describes FitEx-ECS as focused on walking and FitEx-ECS+ Yoga as including postures, breathwork, and mindfulness.

The primary outcome was change in minutes per day of MVPA from baseline to 8 weeks, assessed using continuous Fitbit tracking. The registry states that participants needed at least 4 days per week of wear time at each time point for inclusion in the primary measure. The posted arm-level outcome counts are 16 for usual care, 8 for FitEx-ECS, and 14 for FitEx-ECS+ Yoga. These outcome counts do not match the overall enrollment figure, and the reason for that difference is not reported in the registry record.

Although the primary outcome description names comparisons of both FitEx groups with usual care, the posted comparison estimate is for FitEx-ECS+ Yoga versus usual care. A result for FitEx-ECS versus usual care is not reported in the registry record. The trial also lists secondary outcomes, including quality-of-life and flourishing measures, and the registry record lists 17 posted secondary outcomes. Details of the planned statistical analysis, including the trial's original sample-size assumptions, 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Minutes per day of moderate to vigorous physical activity (MVPA) over 7 days was compared from 8 weeks to baseline data. Participants need to have at least 4 days per week of wear time at each time point to be included.

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: Completion of all questions and survey information was not required for study enrollment. Data that was obtained is provided.

6. Primary Endpoint

The registry lists the primary outcome as Moderate to Vigorous Physical Activity of Endometrial Cancer Survivors, measured over Change from baseline to 8 weeks (post-intervention).

The primary endpoint is change in objective moderate-to-vigorous physical activity, measured as minutes per day of MVPA. Fitbit tracking was used to obtain continuous activity data. The timeframe is change from baseline to 8 weeks, described as the post-intervention assessment. The posted arm values are means, with standard deviations describing variation among participants.

MVPA is used as an outcome because the trial asks whether the walking-focused programs, with or without yoga, are associated with changes in participants' physical activity. Objective tracking offers a way to assess activity beyond participants' own reports. In general, continuous monitoring can capture activity over multiple days, while eligibility requirements for device wear help ensure that a participant has enough recorded time to contribute to the measure. The registry specifies at least 4 days per week of wear at both assessment points.

The endpoint is a change measure, so its interpretation depends on both baseline and follow-up activity. The posted mean changes are 3.7 minutes per day for usual care, 12.14 for FitEx-ECS, and 3.15 for FitEx-ECS+ Yoga. The posted comparative estimate is available for FitEx-ECS+ Yoga versus usual care. It should not be treated as a result for the FitEx-ECS comparison, which is not reported in the registry record.

7. Results Posted in the Registry

• FitEx-ECS+ Yoga: mean 3.15 versus 3.70 on control; difference -0.55 (95% CI -19.14 to 18.04), standardized effect d = -0.02; z-test p = 0.954.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is measured in minutes per day rather than as a category such as meeting or not meeting a threshold. The registry specifies that the reported arm values are means and that the spread is reported as a standard deviation. A mean describes the average observed change in each group. A standard deviation describes how dispersed individual observations are around that mean; it is not a measure of uncertainty in the mean itself.

The comparison of interest is a difference in mean change between groups. For FitEx-ECS+ Yoga versus usual care, the posted estimate is -0.55 minutes per day. The arm means used for this comparison are 3.15 for FitEx-ECS+ Yoga and 3.7 for usual care. The negative sign indicates that the estimated mean change was lower in the yoga group than in usual care under the comparison's stated direction. This estimate is a difference in group averages, not a description of the change experienced by every participant.

A confidence interval expresses the precision of an estimate under the statistical model used. The 95% confidence interval for this mean difference runs from -19.14 to 18.04 minutes per day. In general, a confidence interval gives a range of values that are reasonably compatible with the observed data and model; a wider interval indicates less precision. It is not a range containing every participant's outcome, nor does it assign a probability to the true value after the data have been observed.

The unadjusted p-value for the posted comparison is 0.954. In general, a p-value measures how unusual data at least as inconsistent with a null hypothesis would be if that hypothesis and the analysis assumptions were correct. It does not measure the size or importance of a difference, and it is not the probability that the null hypothesis is true. The registry labels the reported p-value as unadjusted; whether any adjustment for multiple comparisons was planned or performed is not reported in the registry record.

The arm-level standard deviations are 26.4 for usual care, 40.75 for FitEx-ECS, and 25.5 for FitEx-ECS+ Yoga. These values indicate considerable variation in observed changes relative to the group mean changes. In general, high variability makes group averages harder to estimate precisely, especially when the number of observations is limited. The posted counts for the primary outcome are 16, 8, and 14 in the respective groups.

The registry describes the primary endpoint as change from baseline to 8 weeks and says that at least 4 days of Fitbit wear per week were required at both time points. Requiring adequate wear can improve the completeness of the measured activity data used in the endpoint. It can also mean that the analyzed participants differ from those without qualifying data. The registry does not report the number excluded for wear time, the handling of partially observed data, or analyses assessing the consequences of missing measurements.

The comparison is based on a randomized parallel-group design, but the statistical model used for the posted estimate is not reported in the registry record. Details such as adjustment for baseline activity, covariates, clustering by support team, or other design features are also not reported in the registry record. These details matter because an adjusted estimate may differ from an unadjusted group comparison, and observations from people participating together may not be statistically independent. There is not enough information in the registry record to determine whether or how such considerations were incorporated.

The trial is described as a pilot randomized controlled trial. Pilot results can be useful for describing feasibility and generating estimates for future work, but small outcome groups and imprecise estimates limit the strength of conclusions about between-group differences. General statistical principle: the reliability of a treatment-effect estimate depends not only on randomization, but also on outcome completeness, variability, analysis choices, and the number of observations contributing to the comparison.

The registry records 33 outcome measures and 17 posted secondary outcomes. A large set of outcomes raises the general issue of multiplicity: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or the complete statistical analysis plan. The unadjusted p-value for the primary comparison should therefore be interpreted as the posted result for that comparison, not as a summary of all possible analyses.

The posted sample-size illustrations use the observed effect as a starting point and describe hypothetical planning under stated assumptions. These planning calculations are separate from the trial's original design; its own sample-size justification is not reported in the registry record. Such illustrations do not establish that the completed pilot had a particular probability of detecting an effect.

10. Confidence Intervals and Precision

The estimated mean difference for FitEx-ECS+ Yoga versus usual care is -0.55 minutes per day. Its 95% confidence interval extends from -19.14 to 18.04. The interval spans zero, so the data are compatible with no difference as well as with differences in either direction. The point estimate alone should not be read as a precise estimate of the underlying group contrast.

The interval is wide relative to the small point estimate. This means the estimate leaves substantial uncertainty about the size and direction of the difference. The result is not precise enough to rule out a potentially meaningful difference in either direction, although the registry record does not define a threshold for clinical importance. A confidence interval reflects uncertainty in the estimated group contrast under the analysis assumptions; it does not describe the range of individual responses.

The primary outcome counts are 16 for usual care and 14 for FitEx-ECS+ Yoga. The small number of observations contributing to the comparison, together with the observed variability in the arm values, is relevant when considering the interval's breadth. The registry record does not provide additional precision measures, such as an adjusted estimate or a model-based explanation for the interval.

The unadjusted p-value is 0.954. This is not evidence that the groups are equivalent. Demonstrating equivalence would require a prespecified margin and an analysis designed to assess whether the plausible difference lies within that margin; such a margin and analysis are not reported in the registry record. The more useful reading is that the posted estimate is near zero but imprecise, and that a broad range of group differences remains compatible with the data and stated interval.

11. 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 sample-size illustrations are hypothetical planning calculations, not counts of participants enrolled or analyzed. They are for participants per arm, rather than total events. The assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect defined as the stated fraction of the observed effect. The trial's original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column indicates the number of participants per arm that the planning calculation estimates would be needed to have an 80% chance of detecting the selected effect under those assumptions, if the effect and model assumptions were correct. The 90% power column represents a higher target chance of detection and therefore requires more participants per arm for the same assumed effect. These are planning targets, not guarantees about what a future study will find.

The rows illustrate planning for 100%, 75%, and 50% of the observed effect. For the 100% effect assumption, the illustration gives 35,043 participants per arm for 80% power and 46,912 for 90% power. For 75% of the observed effect, the corresponding figures are 62,298 and 83,399 participants per arm. For 50% of the observed effect, they are 140,169 and 187,647 participants per arm. Smaller effects require more participants to detect under otherwise unchanged assumptions.

These figures are unusually large because the posted comparison's observed mean difference is small relative to its variability. They should not be treated as a recommendation or as a reliable design target without considering the uncertainty in the pilot estimate and the assumptions of the calculation. This is not observed power: it is a planning illustration based on the observed effect, not a retrospective measure of the completed trial's ability to detect an effect.

12. 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 = -0.550; pooled standard deviation σ = 25.986.
2. n = 2 × (1.96 + 0.842)² × 25.986² / -0.550² = 35,042.2, rounded up to 35,043 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 <- -0.55                      # observed difference in means
sigma <- 25.9860195929603                     # 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(5737745)
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 = 35,043 (80% power), 46,912 (90% power)
 75% of observed effect: n per arm = 62,298 (80% power), 83,399 (90% power)
 50% of observed effect: n per arm = 140,169 (80% power), 187,647 (90% power)
power.t.test: 35043.2 
Simulated power at n = 35,043 per arm: 0.803 (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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists 33 outcome measures and 17 posted secondary outcomes. The study description also names several domains beyond physical activity, including quality of life, self-compassion, flourishing, self-efficacy, social support, habit formation, and fruit and vegetable consumption. When many outcomes or comparisons are examined, multiplicity is a statistical concern: the chance of finding at least one result that appears unusual can rise even when there is no true effect. The registry record does not report whether a correction for multiple comparisons was planned or applied, or whether outcomes were arranged in a prespecified hierarchy.

The posted primary comparison has an unadjusted p-value of 0.954. Without the statistical analysis plan, it is not possible to establish whether the primary outcome was the sole confirmatory analysis or how the other outcomes were incorporated into the interpretation. The registry record lists zero analyses in its analysis count, while also posting outcome values and a primary comparison estimate; it does not explain that difference.

Missing-data methods are also not reported in the registry record. The primary outcome description states that participants needed at least 4 days per week of wear time at baseline and at 8 weeks. The record does not state how many participants failed this requirement, whether missing measurements were imputed, or whether complete-case analysis was used. It also does not report sensitivity analyses for missingness.

The primary outcome counts are lower than the registry's enrollment of 111, but the registry record does not explain the flow from enrollment or randomization to the counts contributing to the outcome. The analysis population is not specified: it is not reported whether participants were analyzed according to their randomized assignment, according to intervention received, or under another rule. These gaps limit assessment of possible selection bias and of how well the posted estimates represent the randomized groups.

14. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists zero serious adverse events in each of the three groups and zero deaths in each group. It also lists zero other adverse events in each group. The corresponding at-risk counts are 18 for usual care, 29 for FitEx-ECS, and 57 for FitEx-ECS+ Yoga. These safety counts differ from the primary outcome counts and should be read as a separate set of registry figures.

Zero recorded events means none were reported in these entries; it does not establish that no adverse events occurred outside the registry's reporting definitions or observation process. The record does not provide event descriptions, severity details beyond the serious-event category, or an explanation of how the safety at-risk groups were defined. The listed counts do not support a direct comparison of safety rates without further information about follow-up, ascertainment, and the populations included.

In general, adverse-event counts describe what was recorded during the specified study period, while an absence of recorded events is not proof of absence of risk. The registry does not list serious adverse event terms for these groups. These figures should therefore be interpreted as registry reporting, not as a comprehensive safety assessment or as medical advice.

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

The posted primary result is an estimate of the difference in mean change in MVPA between FitEx-ECS+ Yoga and usual care. The estimate is -0.55 minutes per day, and the 95% confidence interval ranges from -19.14 to 18.04. The observed point estimate is close to zero, but the interval is broad and includes differences in both directions. The result is therefore uncertain rather than a clear demonstration of equality or of a particular effect.

This comparison addresses the yoga program against usual care, not the walking-focused FitEx-ECS program. Although the registry describes the primary question as including both intervention comparisons, the result for FitEx-ECS versus usual care is not reported in the registry record. It would be inappropriate to use the yoga estimate as a substitute for that missing comparison.

The registry describes the trial as a pilot and records an enrollment of 111, while the primary outcome estimates use smaller arm counts. The required Fitbit wear time may help define which measurements were usable, but the record does not explain the participant flow or missing-data handling. These limitations affect how confidently the posted result can be generalized to all enrolled or randomized participants.

The result does not establish whether a change would be important to survivors, because the registry does not report a threshold for meaningful change. Nor does an unadjusted p-value of 0.954 establish equivalence or prove that there is no effect. The posted evidence is best understood as an imprecise pilot estimate that can inform questions for further study, subject to uncertainty in its magnitude and analysis details.

16. Why This Trial Matters Statistically

This trial raises statistical issues common to behavioral interventions in survivorship research. The primary outcome is based on objective activity tracking over time, but the measure depends on adequate device wear. A wear-time requirement can support consistent measurement while also determining which participants contribute to the analysis. Understanding that selection requires participant-flow and missing-data information, which is not reported in the registry record.

The three-arm design includes usual care, a walking-focused program, and a program combining FitEx with yoga. The posted primary comparison covers only FitEx-ECS+ Yoga versus usual care. A separate estimate for FitEx-ECS versus usual care is not reported in the registry record, so the evidence presented does not fully address the stated two-comparison primary question.

The contrast has a small point estimate and a wide confidence interval. That combination illustrates why an estimate should be read together with its precision: a value near zero does not, by itself, show that the groups are equivalent. The pilot context and small outcome counts make it especially important to distinguish a preliminary estimate from a definitive conclusion.

The record also names many secondary outcomes. Without a reported analysis plan or multiplicity strategy, it is difficult to know how the full set of outcomes was intended to inform conclusions. The large planning figures based on fractions of the observed effect further illustrate how uncertain small pilot estimates can translate into unstable planning calculations. Statistically, the trial matters as an example of why transparent reporting of analysis populations, missing-data methods, prespecified comparisons, and precision is essential when interpreting early clinical research.

17. 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 does not report the trial's original sample-size justification, detailed statistical analysis plan, or the model used for the posted comparison. It is therefore not possible to assess whether the analysis matched a prespecified plan, whether baseline activity or other covariates were included, or whether any group structure related to support teams was accounted for.

The primary outcome counts are 16 for usual care, 8 for FitEx-ECS, and 14 for FitEx-ECS+ Yoga, smaller than the overall enrollment of 111. Although Fitbit wear eligibility is described, the record does not explain participant flow, exclusions, missing observations, or the analysis population. The reason for the difference between overall enrollment and outcome counts is not reported in the registry record.

The posted primary estimate covers FitEx-ECS+ Yoga versus usual care, while the stated primary question also includes FitEx-ECS versus usual care. The result for the latter comparison is not reported in the registry record. The available comparison therefore cannot answer the full stated primary question.

The registry reports many outcome measures and secondary outcomes but does not report a multiplicity plan. The posted p-value is unadjusted. The record also does not provide a threshold for a clinically meaningful change in MVPA, limiting interpretation of the estimate's practical importance. Finally, the safety entries report zero events but do not describe ascertainment methods or follow-up details, so they should not be read as a complete safety evaluation.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: FitEx for Endometrial Cancer Survivors: Initial Efficacy — NCT05737745.
• Registry record last updated 2025-05-09; status last verified 2025-04.
• Results first posted 2025-05-09.
• 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.

21. Record Summary

NCT05737745 is a completed, randomized, parallel-group pilot trial of FitEx for endometrial cancer survivors. Its three groups were usual care, FitEx-ECS, and FitEx-ECS+ Yoga. The primary outcome was change in Fitbit-measured MVPA from baseline to 8 weeks, with at least 4 days per week of wear required at both assessment points.

The posted primary comparison is FitEx-ECS+ Yoga versus usual care. The estimated mean difference is -0.55 minutes per day, with a 95% confidence interval from -19.14 to 18.04 and an unadjusted p-value of 0.954. The estimate is imprecise, and the registry record does not report the primary comparison for FitEx-ECS versus usual care.

Important analysis details, including missing-data handling, the analysis population, multiplicity procedures, and the trial's original sample-size justification, are not reported in the registry record. The posted results are best read as preliminary estimates from a pilot study rather than definitive evidence about the programs.