Feasibility of Home-based Exercise Program for Adults With Cystic Fibrosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility of Home-based Exercise Program for Adults With Cystic Fibrosis (NCT05239611), a randomized phase 2 study. The primary outcome is Cardiorespiratory Fitness Assessment- Modified Shuttle Walk Test Result.

2. Clinical Question

3. Trial Design

This was a Phase 2, randomized, parallel-group study listed as completed. The registry reports enrollment of 21 and describes two groups: xenon MRI only, without exercise intervention, and xenon MRI with exercise coaching. The first group received usual standard of care and underwent xenon MRI. The second received weekly coaching and also underwent xenon MRI. The stated study objective was to evaluate feasibility and impact on clinical and patient-centered outcomes in adults with cystic fibrosis, with the aim of informing design of a larger clinical trial.

The registry lists the study as unmasked. It does not report how the random sequence was generated, whether allocation was concealed, or whether outcome assessment was masked. These details matter because random assignment can support a fair comparison, while predictable assignment or awareness of treatment can affect study conduct and outcome assessment. The record does not report the methods used to reduce those risks.

The start date was 2022-03-15, and the primary completion date was 2023-08-03. Those dates describe the registry record; they do not establish the duration of follow-up for each participant beyond the primary endpoint’s stated 3-month timeframe. No additional visit schedule is reported.

The intervention listing names xenon MRI as a diagnostic test, while the group descriptions distinguish whether exercise coaching was included. The registry record does not report details such as the exercise regimen, coaching duration, attendance, or adherence. It also does not report a protocol-level sample-size justification or the planned analysis methods. The study’s feasibility objective is therefore relevant context: these posted data should be read as results from a pilot study, not as a definitive estimate of an exercise program’s effect.

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 Cardiorespiratory Fitness Assessment- Modified Shuttle Walk Test Result, measured over 3 months.

The primary endpoint is the change in modified shuttle walk test performance, expressed as the change in the number of shuttles completed. The registry specifies that one shuttle is 10 meters and describes the change as measured between baseline or enrollment and study completion at 3 months. This test is being used to assess cardiorespiratory fitness through performance during a walking test. It is a functional measure, rather than a direct measure of lung function or quality of life.

The posted endpoint is continuous: it can take different numerical values rather than representing a simple event count. The registry reports the mean change and standard deviation for each group. A mean summarizes the group’s average recorded change, while the standard deviation describes how dispersed individual changes are around that mean. Neither summary alone shows the uncertainty around a group mean or establishes whether the groups differ.

The record does not specify the arithmetic convention used to calculate change, such as whether the completion value was subtracted from baseline or vice versa. As a result, the negative group means should be described as posted negative changes, without assigning a direction such as improvement or decline. The measure is useful for asking whether walking-test performance changed over the stated study period, but the registry record does not report a threshold for a clinically meaningful change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary outcome summarize?

The primary measure is continuous: the number of modified shuttle walk test shuttles completed, expressed as a change between baseline or enrollment and study completion. The registry reports a mean for each group. In general, a mean is the arithmetic average of observations and gives a concise description of the group’s central result. It can be useful when the outcome is numerical, but it does not reveal whether most participants were close to the average or whether a few values strongly influenced it.

The registry also reports a standard deviation for each group. In general, the standard deviation describes the spread of individual observations around the mean. It is not a confidence interval and does not directly quantify how precisely the mean or a treatment contrast has been estimated. The posted standard deviations, 9.33 and 9.84, describe variability in the observed group changes; they should not be interpreted as uncertainty intervals for the means.

Why is a between-group estimate important?

For a randomized parallel-group study, the main comparative question is usually about the outcome in the intervention group relative to the outcome in the comparator group. Separate group means are descriptive. A formal analysis would estimate a contrast between groups and report its uncertainty, often with a confidence interval, with or without a significance test depending on the analysis plan.

In general, a confidence interval gives a range of values compatible with the data and the statistical method, and conveys precision as well as the estimated effect. A narrow interval indicates more precision than a wide interval, though interpretation also depends on the outcome and the clinical context. The registry record does not report a between-group estimate or confidence interval for this endpoint. It lists no posted analyses, so neither a sponsor analysis nor a recalculated comparison is available for interpretation.

What does randomization add?

In general, random assignment aims to make treatment groups comparable with respect to both measured and unmeasured characteristics at the point of assignment. It can support causal interpretation when allocation is implemented appropriately, follow-up is adequate, and analysis preserves the randomized comparison. Randomization does not guarantee that small groups will have identical baseline characteristics, nor does it eliminate the effects of missing outcomes, non-adherence, or outcome-assessment bias.

The record labels allocation as randomized and the study model as parallel. It does not report sequence generation, allocation concealment, baseline balance, participant flow, or the analysis population. It also lists masking as none. The consequences of those design features cannot be assessed fully from the posted information.

How should planning illustrations be read?

In general, a sample-size calculation is a prospective planning exercise based on assumptions about the effect to detect, variability, significance level, allocation, and statistical method. The registry record says its planning illustration uses the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation; it also describes the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not the trial’s own design justification. The record does not report the protocol’s sample-size justification.

Such planning numbers are not observed power. Once a study has been conducted, a calculation based on the observed effect does not establish how likely the trial was to detect a true effect. The value of a planning illustration depends on the assumptions chosen, and the observed effect in a small pilot study can be imprecise. Any displayed planning numbers should therefore be understood as illustrative requirements under those assumptions, not as evidence that the study was adequately powered or underpowered.

What role does over-dispersion play?

General statistical context: over-dispersion describes variation greater than expected under a model’s assumptions. It can make standard errors too small if an analysis assumes less variability than the data contain. For this endpoint, the registry reports standard deviations, but it does not report an analysis model or a finding of over-dispersion. The concept should not be taken to mean that over-dispersion was observed in this study.

For a continuous outcome, the spread of participant values affects how precisely a group mean or group contrast can be estimated. A larger spread generally makes a given estimate less precise when other design features are held constant. The posted group standard deviations describe dispersion, but the record does not provide enough information to assess model assumptions or derive a valid uncertainty estimate for a contrast.

What can be inferred from the posted results?

The available primary-outcome statistics are means and standard deviations for each group. They describe the posted data but do not establish statistical significance, clinical importance, or a causal effect. The registry record does not report adjusted analyses, an analysis population, a missing-data method, or interim analyses. These omissions prevent assessment of whether the posted summaries correspond to the planned analysis or how incomplete data were handled.

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("Xenon MRI Only, Without Exerercise Intervention", "Xenon MRI With Exercise Coaching")
n   <- c(9, 12)
m   <- c(-6.67, -7.63)
sp  <- c(9.33, 9.84)
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  Xenon MRI Only, Without Exerercise Intervention  9  -6.670  9.330  -13.842  0.502
CARM  Xenon MRI With Exercise Coaching  12  -7.630  9.840  -13.882  -1.378

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes: Forced Expiratory Volume in 1 Second, Quality of Life Assessment, and Exercise Time. It reports five outcome measures overall, but the record does not provide results for these secondary outcomes in the information available for this analysis. The registry does not report a prespecified hierarchy among outcomes, a multiplicity adjustment, or a plan for controlling the chance of false-positive findings across multiple tests. Those details are not reported in the registry record.

In general, testing several outcomes can increase the chance that at least one result appears statistically unusual by chance. Multiplicity methods can address that issue, but the appropriate method depends on the trial’s aims and analysis plan. With no posted inferential results or stated plan, it is not possible to assess how multiplicity was handled in this study.

The number of participants with outcome data is not reported separately from enrollment, and the record does not describe missing primary-outcome observations, reasons for missingness, or an imputation method. It also does not state whether the analysis followed intention-to-treat principles, used a per-protocol population, or applied another analysis population. These details matter because excluding participants or handling missing outcomes differently can affect estimates and their uncertainty.

The record does not report interim analyses or stopping rules. No conclusion about whether interim analyses occurred should be drawn from their absence in the registry information. The missing analysis-plan and follow-up details limit reproducibility and make it difficult to determine how the posted group summaries relate to the intended statistical analysis.

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.

The registry reports zero serious adverse events among 9 participants at risk in the xenon MRI only, without exercise intervention group, and zero among 12 participants at risk in the xenon MRI with exercise coaching group. It also reports zero other adverse events among 9 and 12 participants at risk in those respective groups, and zero deaths in both groups. No serious adverse event terms are listed.

These are event counts recorded in the registry, not evidence that the interventions carry no risk. A zero count in a small study can occur even when an event is possible, and the record does not provide enough information to estimate the rate of uncommon harms. The registry also does not report event definitions, the observation window for safety collection, severity details, relatedness assessments, or withdrawals due to adverse events. The figures should therefore be read narrowly: no serious or other adverse events and no deaths are recorded in the posted safety results for the listed groups. They do not establish safety beyond the study’s recorded experience.

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

The primary endpoint results describe average changes in modified shuttle walk test performance in two randomized groups over the stated 3-month period. The registry reports a mean change of -6.67 shuttles, with a standard deviation of 9.33, for the group receiving xenon MRI only, without exercise intervention. For the group receiving xenon MRI with exercise coaching, it reports a mean change of -7.63 shuttles, with a standard deviation of 9.84. The record does not specify the convention used to calculate the change, so the negative values should not be given a directional interpretation.

The posted data do not establish whether exercise coaching changed the outcome relative to the comparator. There is no between-group estimate, confidence interval, or p-value in the registry record, and no posted analyses are listed. A comparison cannot be reconstructed reliably from these summaries alone. The standard deviations describe participant-level spread, not the precision of a treatment contrast.

The data also do not establish whether any difference would be clinically meaningful. The registry does not report a threshold for meaningful change on the modified shuttle walk test, nor does it report participant-level results or the secondary outcome results. A numerical endpoint result is only one part of evaluating a pilot intervention, and it does not answer all questions about feasibility, acceptability, or implementation.

The registry’s stated purpose was to assess feasibility and impact and inform the design of a larger clinical trial. The available record supplies the design, group descriptions, endpoint summaries, and safety counts, but does not report detailed feasibility measures or a complete statistical analysis. The study can therefore be viewed as a small pilot with descriptive outcome data, while the uncertainty around comparative effects remains unquantified.

These results neither prove nor disprove an effect of the coaching intervention. They should not be used as a treatment recommendation. A larger study with a prespecified analysis, complete outcome reporting, and explicit handling of missing data could provide a more precise estimate, but the registry record does not describe such a study’s design or results.

14. Why This Trial Matters Statistically

This trial is statistically relevant because it combines random allocation with a pilot objective and a continuous functional outcome. Randomization is intended to support a fair comparison, but a randomized label alone does not supply the estimate needed to understand the comparative result. The registry reports group means and standard deviations, while omitting the between-group estimate and its uncertainty. That distinction is central: descriptive summaries show what was recorded in each group, whereas comparative inference addresses how compatible the results are with different possible group effects.

The study also illustrates why variability matters. The standard deviations indicate that participant changes were not tightly concentrated around the group means. In general, participant-to-participant variation reduces precision and should be reflected in uncertainty estimates. Without confidence intervals or a reported model, readers cannot assess the precision of a group contrast or distinguish a potentially important effect from random variation.

Feasibility studies can help identify practical questions for a later trial, such as whether participants can be recruited, followed, and engaged with an intervention. The registry’s stated objective includes that role, but detailed feasibility outcomes are not reported in this record. A pilot study’s contribution is therefore not necessarily a definitive test of efficacy; operational outcomes and the quality of measurement can be as important as an initial clinical estimate.

Finally, planning calculations based on an observed effect should not be confused with observed power or with a formal sample-size justification. Their assumptions need to be transparent, and an effect from a small pilot may be uncertain. This record highlights the value of reporting the planned estimand, analysis population, missing-data approach, uncertainty intervals, and feasibility measures alongside outcome summaries.

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 registry record does not report baseline characteristics, so it is not possible to assess how the two groups compared before intervention or to understand which adults with cystic fibrosis are represented. Eligibility criteria, recruitment setting, and participant flow are also not reported. Although enrollment is stated, the number with observed primary-outcome data is not separately given.

Details of the exercise intervention are limited to weekly coaching. The record does not specify the exercise activities, intensity, duration, progression, or adherence. It also does not report how coaching delivery or fidelity was assessed. Usual standard of care is named as the comparator, but its content is not described. These gaps make it difficult to assess how reproducible the intervention would be in another setting.

The primary outcome is described as change between baseline or enrollment and study completion at 3 months, but the arithmetic direction is not specified. No threshold for a meaningful change is reported. The registry provides group means and standard deviations without a between-group estimate, confidence interval, or p-value, limiting assessment of comparative effect and precision.

The record does not describe missing-data handling, the analysis population, adjustment for baseline values, or any other analysis model. It also does not report the randomization sequence method, allocation concealment, or blinded outcome assessment. The study is listed as unmasked, and the consequences of that design feature cannot be evaluated fully from the available details.

Finally, detailed feasibility outcomes and results for the listed secondary outcomes are not reported in the registry record. Safety counts are available, but event definitions and the safety observation period are not described. These limitations constrain interpretation of both the clinical endpoint and the broader feasibility objective.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Feasibility of Home-based Exercise Program for Adults With Cystic Fibrosis — NCT05239611.
• Registry record last updated 2025-06-12; status last verified 2025-06.
• Results first posted 2025-06-12.
• 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

The registry record describes a completed, Phase 2, randomized, parallel-group, unmasked study of a home-based exercise program for adults with cystic fibrosis. It lists enrollment of 21 and compares usual standard of care with xenon MRI against usual care, xenon MRI, and weekly exercise coaching. The primary endpoint is change in modified shuttle walk test shuttles at 3 months.

The posted mean changes were -6.67 shuttles, with standard deviation 9.33, for the xenon MRI-only group, and -7.63 shuttles, with standard deviation 9.84, for the exercise-coaching group. No between-group analysis or uncertainty interval is reported. The safety record lists zero serious adverse events, zero other adverse events, and zero deaths in both groups. Details on missing data, analysis populations, multiplicity, and feasibility outcomes are not reported in the registry record.