Twice Weekly Steroids and Exercise as Therapy for DMD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Twice Weekly Steroids and Exercise as Therapy for DMD (NCT04322357), a randomized phase 2 study. The primary outcome is Change in BMI.

2. Clinical Question

The study's stated rationale is to examine whether low-dose twice-weekly prednisone and exercise training may affect disease progression, muscle strength and physical function. The registry summary notes that daily prednisone is standard care and is associated with adverse side effects, and that exercise in DMD had not been adequately explored. Those statements describe the study's motivation, not conclusions established by the posted BMI results.

The question has several components: whether BMI changes during the observed period, whether those changes differ between regimens, and whether exercise is associated with a different pattern of change. The registry reports arm-level means and standard deviations but does not report an analysis answering the comparative questions. The distinction matters because a within-arm change and a between-arm treatment contrast answer different statistical questions.

3. Trial Design

NCT04322357 is listed as a phase 2, randomized, open-label, parallel study, with enrollment of 21 and status completed. The record gives a start date of 2020-07-30 and a primary completion date of 2024-12-04. These registry descriptors identify the broad study structure; they do not provide the full protocol or explain the statistical choices made during conduct of the trial.

The intervention descriptions include prednisone and exercise training. The twice-weekly glucocorticoid group is described as containing participants randomized to one of two plans: twice-weekly prednisone alone for 12 months, or twice-weekly prednisone for 6 months followed by twice-weekly prednisone plus exercise for 6 months. The exercise is described as structured, supervised and home-based. A separate group of participants receiving daily glucocorticoids is described as undertaking 6 months of exercise training.

The record also describes daily glucocorticoid data from age-matched, ambulatory participants in the ImagingDMD database as a historical control. A historical control is not the same as a group concurrently randomized within the trial. Differences in participant selection, timing, measurement practices or other characteristics can complicate comparisons, and the registry record does not report details sufficient to assess those issues.

The posted primary outcome is change in BMI from baseline up to 12 months. It is reported as a mean with standard deviation. The arm-level results list 15 participants for twice-weekly glucocorticoid without exercise, 4 for daily glucocorticoid with exercise, and 2 for twice-weekly glucocorticoids with exercise. The record does not explain the relationship between each listed outcome count and the total enrollment, or describe any participant flow that would clarify who contributed data at each assessment.

Although randomization is listed for the study, the record does not report the allocation sequence, concealment procedures, or a detailed account of which participants were randomized to which groups. Masking is listed as none. The registry record does not report a formal sample-size justification or a complete statistical analysis plan.

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.

Before assignment: 21 patients were enrolled in the study. Of these, 17 steroid-naive boys with DMD were enrolled into the 12 month twice weekly steroid arm and 2 of the 17 underwent cycle exercise training from month 6 to 12. Of the 21 enrolled patients, 4 boys on daily steroids were enrolled into a 6-month exercise training arm.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Change in BMI was a primary outcome for only 1 arm (Twice weekly glucocorticoid).

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 Change in BMI, measured over Baseline up to 12 months.

BMI combines a participant's weight and height into a measure expressed in kg/m^2. The registry defines the primary outcome as the change in BMI over the period from baseline up to 12 months. It describes the endpoint as a mean, with standard deviation as the measure of spread. The listed outcome population is only one arm: twice-weekly glucocorticoid.

In general, a change measure describes how an outcome differs from its baseline value over a defined follow-up period. Reporting a mean change gives the average change among the participants included in that arm's outcome summary. The standard deviation describes how dispersed individual changes are around that mean; it is not a confidence interval and does not by itself show how precisely the mean is estimated.

BMI is used as a combined measure based on weight and height. A change in BMI is not itself a direct measure of muscle strength, physical function or disease progression. The study summary discusses those broader aims, but the posted primary endpoint is BMI change. The registry record does not report a separate primary outcome estimate for strength or physical function.

The arm-level mean changes are 0.67 kg/m^2 for twice-weekly glucocorticoid without exercise, 1.34 kg/m^2 for daily glucocorticoid with exercise, and 1.8 kg/m^2 for twice-weekly glucocorticoids with exercise. The corresponding standard deviations are 1.4, 1.7 and 1.9. These are descriptive summaries, and the registry does not report a confidence interval or a test of differences between these means.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

These results concern a continuous outcome: change in BMI, measured in kg/m^2. For a continuous endpoint, an arm-level mean describes the average value among participants included in that summary. The standard deviation describes variation among their observed changes. It is a measure of spread in the data, not a measure of the precision of the mean and not a test of a treatment effect.

The posted means and standard deviations are 0.67 and 1.4 for twice-weekly glucocorticoid without exercise, 1.34 and 1.7 for daily glucocorticoid with exercise, and 1.8 and 1.9 for twice-weekly glucocorticoids with exercise. The record gives the sample sizes for these summaries as 15, 4 and 2, respectively. Because the groups differ in size, the means should not be treated as equally precise. In general, the uncertainty of an estimate depends on both the variability in observations and the amount of data available.

A treatment comparison is different from separate arm summaries. A comparison estimates how much the outcome differs between groups, with uncertainty quantified under a specified analysis. The registry record does not report such a comparison for this endpoint. It also does not report a confidence interval, a test statistic or a p-value for differences in BMI change. Consequently, statistical significance cannot be assessed from the posted arm means and standard deviations alone.

The registry's sample-size assumptions describe a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, a normal approximation, and a target effect defined as a stated fraction of the observed effect. Such calculations are hypothetical planning exercises. They are not evidence that the trial had a particular probability of detecting an effect, and they are not observed power. The record does not report the trial's own sample-size justification, and no numerical sample-size results are included in the information summarized for the posted analysis.

General explanation: a planning calculation asks how many participants per arm might be needed under chosen assumptions to detect a specified effect with a chosen power and significance level. The result depends on the assumed effect, variability, allocation and analysis. When a planning effect is derived from an observed estimate, it inherits uncertainty from that estimate. This is especially important when some listed groups are small. A planning illustration cannot replace an analysis of the data collected in the trial.

The record describes a randomized, open-label, parallel study. Randomization can support fair comparisons by balancing measured and unmeasured characteristics on average, but that benefit applies to a defined randomized contrast and does not remove uncertainty. The registry record does not report the allocation sequence, concealment details, or the analysis population used for the BMI summaries. It also describes a historical control for daily glucocorticoid data, which is distinct from a concurrently randomized control group.

The arm descriptions suggest different treatment sequences: twice-weekly prednisone alone, twice-weekly prednisone followed by exercise while continuing prednisone, and daily glucocorticoids with exercise. Those are not interchangeable exposure histories. A direct interpretation of differences would require a clearly stated estimand, meaning a precise definition of the treatment contrast, outcome, participants and follow-up being evaluated. The registry record does not report such an estimand or a statistical model for the primary outcome.

General explanation: estimates can be adjusted for baseline characteristics or analyzed without adjustment. Adjustment can account for specified prognostic factors, but the choice of variables and model should be planned and reported. The registry record does not report whether the posted means are adjusted, whether baseline BMI was included in a model, or how repeated measurements were handled. No assumptions about those methods can be made from the arm-level summaries.

Variability is notable in relation to the reported group sizes, but no new precision measure can be derived without performing a calculation. General explanation: when individual outcomes vary substantially, a group mean may be estimated less precisely than when outcomes are closely clustered, all else being equal. Very small groups also make it difficult to evaluate distributional assumptions, identify outliers, or distinguish a group pattern from individual variation. The standard deviation alone does not reveal the shape of the outcome distribution.

The registry states that no analyses are posted for the outcome and identifies the lack of estimable two-arm comparisons for a continuous endpoint. That means the posted information supports descriptive reading of the group summaries, not reconstruction of an inferential comparison. Any recalculation from summary statistics would be an unadjusted calculation and would not replace an analysis specified by the sponsor. No discrepancy is reported, but no sponsor comparison is posted to take precedence over a recalculation.

In general, a p-value measures how incompatible observed data are with a specified null model under its assumptions; it does not measure the size or clinical importance of an effect. A confidence interval addresses precision and includes a range of effect values compatible with the model. Neither is reported for a between-group BMI contrast in the registry record. Without them, the posted means should be treated as descriptive rather than as evidence of a statistically established difference.

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("Twice Weekly Glucocorticoid Without Exercise", "Daily Glucocorticoid With Exercise", "Twice Weekly Glucocorticoids With Exercise")
n   <- c(15, 4, 2)
m   <- c(0.67, 1.34, 1.8)
sp  <- c(1.4, 1.7, 1.9)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Twice Weekly Glucocorticoid Without Exercise  15  0.670  1.400  -0.105  1.445
CARM  Daily Glucocorticoid With Exercise  4  1.340  1.700  -1.365  4.045
CARM  Twice Weekly Glucocorticoids With Exercise  2  1.800  1.900  -15.271  18.871

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and no posted secondary outcome measures. It reports no analyses. Although multiple treatment groups and possible contrasts are described, the record does not identify a prespecified set of comparisons or explain how multiplicity was handled. Multiplicity refers, in general, to the interpretive problem that can arise when several hypotheses are tested; the registry record does not report whether any correction or hierarchy was planned.

The record describes BMI change as a primary outcome for only the twice-weekly glucocorticoid arm, and it does not post a two-arm comparison for this continuous endpoint. It therefore does not provide a basis for describing a primary comparative test or its multiplicity adjustment. The registry record does not report interim analyses, stopping rules, or a complete statistical analysis plan.

Missing-data methods and analysis populations are also not reported in the registry record. The posted summaries do not explain whether all enrolled participants contributed to the endpoint, how missing visits were handled, or whether the reported group counts reflect assignment, treatment received, or availability of outcome data. No imputation method, sensitivity analysis, or approach to incomplete follow-up is described. These omissions limit assessment of whether the observed summaries represent all participants as intended.

The registry record does not report a detailed participant-flow account for the primary endpoint. It also does not describe whether baseline measurements were available for all participants included in the change summaries. Without those details, the relationship between enrollment and the endpoint-specific group counts cannot be evaluated from the posted results alone.

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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: rhabdomyolysis (6.7%).

The registry reports serious adverse events and other adverse events separately by group. For twice-weekly glucocorticoid without exercise, 15 participants are listed at risk for serious adverse events and 1 affected; 17 are listed at risk for other adverse events and 3 affected. For daily glucocorticoid with exercise, 4 are listed at risk for serious adverse events and 0 affected, and 4 at risk for other adverse events and 0 affected. For twice-weekly glucocorticoids with exercise, 2 are listed at risk for serious adverse events and 0 affected, and 2 at risk for other adverse events and 0 affected. No deaths are reported in any group.

Rhabdomyolysis is the top serious adverse event term listed, at 6.7%. The registry record does not provide further detail in the registry record reported for this term, such as timing, severity by participant, relatedness assessment or clinical course. The listed affected counts should be read as adverse-event reporting summaries, not as comparative safety estimates.

In general, a zero count in a small group does not establish that an event cannot occur or that a group is safer. Group size, follow-up, event definitions and completeness of reporting all affect what adverse-event counts can show. The registry does not report a formal comparative safety analysis, so differences in these counts should not be interpreted as evidence of a causal safety difference.

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

The results establish that the registry posted mean changes in BMI for three listed groups, with standard deviations and group sizes. The means are 0.67 kg/m^2, 1.34 kg/m^2 and 1.8 kg/m^2, and the standard deviations are 1.4, 1.7 and 1.9. The record lists 15 participants, 4 participants and 2 participants for the corresponding groups. These numbers describe the posted summaries and their observed group sizes.

The results do not establish that exercise caused a change in BMI, that twice-weekly treatment differs from daily treatment, or that any regimen changes muscle strength, physical function or disease progression. The primary outcome is BMI change, and the record does not report inferential comparisons among the groups. The study's stated aims extend beyond BMI, but no secondary outcomes are posted in the record summarized.

In general, a within-group mean change and a between-group treatment effect are distinct quantities. Change in one group may reflect the intervention, natural changes over time, other influences, or a combination. A comparative analysis is needed to estimate whether outcomes differ between treatment strategies, and its interpretation depends on the design and analysis assumptions. The posted means alone cannot separate these possibilities.

The group counts are uneven, and the two participants listed in the twice-weekly glucocorticoid-with-exercise group make its descriptive estimate particularly sensitive to individual observations. The registry does not provide confidence intervals or participant-level results to show the precision and distribution of the changes. Nor does it report details that would permit evaluation of missing outcome data or adjustment for baseline characteristics.

The safety figures are likewise descriptive. The registry reports no deaths and lists one serious adverse event affected participant in the twice-weekly glucocorticoid group without exercise. These counts do not establish comparative risk, particularly where group sizes are small and no formal safety analysis is posted. Overall, the record supports cautious description of the reported outcomes, not a claim of treatment benefit, lack of benefit, or comparative safety.

14. Why This Trial Matters Statistically

This study is statistically interesting because it brings together a medication schedule and an exercise program, while the registry describes both randomized treatment plans and a historical daily-glucocorticoid control. These features make it important to distinguish the design of each group from the analysis needed to compare them. A randomized comparison and a historical-control comparison do not have the same basis for causal interpretation.

The primary endpoint is a continuous measure, BMI change, and the registry posts group means with standard deviations. Such summaries are useful starting points, but a clear treatment-effect interpretation also requires a defined comparison and an estimate of uncertainty. The registry record does not post a comparative analysis, confidence interval or p-value for the primary endpoint. That absence limits what can be concluded statistically, regardless of the apparent ordering of the group means.

The listed group sizes also illustrate why precision matters. The summaries include groups of 15, 4 and 2 participants. Estimates from small groups are generally more vulnerable to sampling variation and individual observations. Descriptive differences can appear large or small without providing reliable evidence about the underlying contrast. The record does not report a formal sample-size justification to show how enrollment was intended to support the primary question.

Finally, the study's stated motivation includes outcomes beyond BMI, but the registry lists no secondary results. This distinction is a useful reminder that a study's rationale and its posted endpoint data are not interchangeable. Statistical interpretation must follow the outcomes and analyses actually reported, while acknowledging what remains unavailable in the registry record.

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 principal limitation for interpreting the primary result is the lack of a reported comparative analysis. Although three arm-level means and standard deviations are posted, the registry record does not provide a confidence interval, test or adjusted estimate comparing groups. The primary outcome is described as applying to only the twice-weekly glucocorticoid arm, further limiting a direct treatment-effect interpretation.

The listed group sizes are uneven, including a group of 2 participants. Such a small group offers limited information about the range of outcomes within that treatment condition, and its mean may be highly influenced by individual observations. The registry does not provide participant-level data or uncertainty estimates to assess that sensitivity.

The daily-glucocorticoid control is described as historical data selected from ImagingDMD, while other groups are described as receiving study interventions. Historical controls may differ from trial participants in ways that affect outcomes. The registry record does not report enough information about matching, selection or analytic adjustment to assess comparability.

The record does not report missing-data handling, analysis populations, participant flow for the endpoint, or whether the posted summaries are adjusted. It does not provide a detailed statistical analysis plan, sample-size justification, or methods for repeated measurements. No secondary outcomes are posted, although the study rationale refers to muscle strength and physical function. Safety counts are descriptive and no comparative safety analysis is reported. These limitations restrict interpretation to the outcomes and summaries actually recorded.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Twice Weekly Steroids and Exercise as Therapy for DMD — NCT04322357.
• Registry record last updated 2026-03-13; status last verified 2025-12.
• Results first posted 2026-03-13.
• 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

NCT04322357, titled “Twice Weekly Steroids and Exercise as Therapy for DMD,” is listed as a completed phase 2 randomized, open-label, parallel study sponsored by the University of Florida. The registry lists enrollment of 21, a start date of 2020-07-30 and a primary completion date of 2024-12-04.

The posted primary outcome is change in BMI from baseline up to 12 months, reported as a mean with standard deviation. The listed arm-level means are 0.67 kg/m^2, 1.34 kg/m^2 and 1.8 kg/m^2, with standard deviations of 1.4, 1.7 and 1.9. The registry record does not report an inferential comparison of these groups or posted secondary outcomes.

Safety reporting lists no deaths and includes rhabdomyolysis as the top serious adverse event term at 6.7%. Overall, the registry provides descriptive outcome and safety summaries but not the comparative analyses needed to estimate treatment effects or their precision.