Exercise to Reduce Obesity in Spinal Cord Injury: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Exercise to Reduce Obesity in Spinal Cord Injury (NCT00270855), a randomized na study. The primary outcome is Change in % Body Fat.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group trial with no masking. The registry lists enrollment of 29 and a completed status. The study start is recorded as 2008-05, and primary completion as 2011-06. The phase is listed as NA. The sponsor was the VA Office of Research and Development.

The two interventions were Arm Crank Ergometry and a Functional Electrical Stimulation Leg Cycle Ergometer. Each arm description specifies a 10-minute warm up, 40 minutes @ 70%HRMax (50RPM), a 10 minute cool down, and exercise 5x/week x 16 weeks. The arm crank program involved upper-body cycling; the FES program involved electrically stimulated lower-extremity cycling. The registry summary says the study was designed to compare the health benefits of upper-extremity exercise with functional electrical stimulation for lower-extremity exercise.

The primary outcome was change in percent body fat, with baseline and 16 weeks identified as the timeframe. For this outcome, the registry reports an Arm Cycling Ergometer group size of 7.0 and an FESLCE group size of 6.0. The overall enrollment and the group sizes reported for this outcome are different entries in the registry. Why they differ, and whether the outcome groups represent all randomized participants, are not reported in the registry record.

The record lists secondary outcomes concerning lower-limb bone measures and blood lipids, including triglycerides, HDL, LDL, total cholesterol, and the total-cholesterol-to-HDL ratio. Specific eligibility criteria, allocation concealment, adherence, and the analysis population are not reported in the registry record. The design information therefore describes the randomized comparison and the exercise schedules, but does not establish how participants were selected, how faithfully exercise was completed, or which participants were included in each analysis.

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: Two exercise groups consisted of an arm crank ergometry group and an FESLCE group.

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 % Body Fat, measured over baseline, 16 weeks.

The primary endpoint was change in percent body fat after the 16 week intervention. It is a continuous measure, and the registry identifies the reported parameter as a mean with standard deviation. The change score was defined as the final, post-intervention value minus the baseline value. Under that definition, a negative mean change indicates that the post-intervention group mean was lower than its baseline mean.

Body fat is used as an outcome because the trial’s stated purpose concerned exercise and obesity in spinal cord injury. The registry summary describes a hypothesis that exercise could increase whole-body energy expenditure and affect muscle mass and metabolic measures. The primary endpoint focuses on body composition rather than directly measuring energy expenditure, muscle mass, insulin sensitivity, glucose effectiveness, or lipid profiles. Those biological and metabolic measures should not be treated as established effects simply because they appear in the study rationale.

A change score expresses movement from baseline to follow-up in the measurement’s stated units. It does not, by itself, show that an intervention caused the change: interpreting treatment effects requires a suitable comparison between randomized groups and consideration of the analysis methods and uncertainty. The registry reports group means and standard deviations, but a between-group estimate and confidence interval for this endpoint are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: percent body fat is measured on a scale, and the result is expressed as a mean change. The registry defines the change as the post-intervention value minus baseline. A mean summarizes the group’s average change, while a standard deviation describes how spread out the individual changes are around that average. These quantities answer different questions. A mean describes the central level of change; a standard deviation describes variation among observations.

What does a change score represent?

A change score combines information from baseline and follow-up by subtracting the baseline measurement from the final measurement. It can be useful when the research question concerns movement over time. Its interpretation depends on the direction chosen for subtraction. In this trial, negative values correspond to a lower post-intervention value than baseline on average. A change score does not identify why a value changed, and within-group movement alone does not isolate the effect of the assigned intervention from other influences over time.

Randomization is intended to make the treatment groups comparable on average at the start of a trial. A comparative treatment effect is ordinarily expressed as a contrast between the groups, with an uncertainty measure such as a confidence interval. The contrast answers a different question from whether each group changed from its own baseline. The posted primary outcome results give a mean and standard deviation for each group, but the registry does not report a between-group estimate or confidence interval. The two-group comparison is marked not estimable in the registry output, so no recalculated comparative effect can be described.

How should the p-values be read?

A p-value describes how compatible the observed data are with a specified statistical hypothesis, under the assumptions of the test. It is not the probability that the hypothesis is true, and it does not measure the size or practical importance of an effect. The registry reports two-sided t-tests with p > 0.05 for each group in analyses labelled non-inferiority or equivalence. It does not identify the test parameter or provide the hypothesis details needed to interpret these entries fully. In particular, these group-specific entries are not a reported test of the difference between the two exercise groups.

A non-inferiority analysis asks whether an intervention is not worse than a comparator by more than a prespecified margin. An equivalence analysis asks whether the difference lies within prespecified bounds in either direction. Both require a clearly stated margin and a result that can be evaluated against it, commonly with a confidence interval. A non-significant p-value from a conventional test does not by itself demonstrate non-inferiority or equivalence. The margin and confidence intervals are not reported in the registry record, so the stated analysis labels cannot be independently evaluated from the posted results.

What does a confidence interval add?

General statistical explanation: a confidence interval gives a range of values compatible with the data and the method used to calculate it. Its width communicates precision: narrower intervals indicate greater precision than wider intervals, all else equal. For a comparative endpoint, an interval around the between-group contrast would help readers assess both the possible direction and the range of effect sizes consistent with the data. No confidence interval is reported for the primary outcome in the registry entries.

General statistical explanation: standard errors and confidence intervals depend on the amount of information and the variability in the observations. Small analysis groups or highly variable measurements can result in uncertain estimates. The reported standard deviations differ between the groups, but the registry does not provide a comparative interval that incorporates the data and chosen analysis method. It would be inappropriate to state a newly calculated interval or p-value when the registry’s comparison is marked unavailable or not estimable.

Why can over-dispersion matter?

General statistical explanation: over-dispersion arises when observed variability is greater than a model expects. It is especially relevant to count outcomes and some generalized models, where assuming too little variability can make standard errors too small and confidence intervals too narrow. The primary outcome is continuous and is summarized by means and standard deviations; the registry does not report an over-dispersion assessment or a model-based analysis for it. This concept is therefore general context, not a reported feature of this trial.

What can planning illustrations tell readers?

General statistical explanation: sample-size calculations can illustrate how much information a future study might need under chosen assumptions. Such calculations depend on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. They are planning illustrations, not evidence about what the completed trial could detect and not a measure of observed power. The registry’s planning description says the illustration uses a two-sided significance level 0.05, equal allocation, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. The effect is not a result of the trial’s design justification: the registry explicitly describes this as a planning illustration computed from the observed effect, not the trial’s own design. The exact planning rows should be interpreted as hypothetical participant requirements under those assumptions, not as observed trial outcomes.

Statistical interpretation also depends on the analysis population and handling of missing outcomes. An intention-to-treat analysis generally evaluates participants according to randomized assignment, while a per-protocol analysis uses a defined set of participants who met protocol criteria. These approaches address related but not identical questions. The analysis population, missing-data method, and adherence information are not reported in the registry record, so the reader cannot determine which approach generated the posted summaries.

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("Arm Cycling Ergometer", "FESLCE")
n   <- c(7, 6)
m   <- c(-1.83, -1.68)
sp  <- c(2.72, 0.98)
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  Arm Cycling Ergometer  7  -1.830  2.720  -4.346  0.686
CARM  FESLCE  6  -1.680  0.980  -2.708  -0.652

11. Analyses Reported by the Sponsor

The registry’s own analysis entries list a two-sided t-test for each arm, each with p > 0.05, and label the analyses as non-inferiority or equivalence. They do not give a numerical estimate for the tested parameter, a confidence interval, or the margin needed to assess a non-inferiority or equivalence claim. The entries also do not report a direct test or estimate comparing Arm Cycling Ergometer with FESLCE.

The posted group means and standard deviations describe change in each arm, but a recalculated two-arm contrast is not available in the registry result output; the comparison is identified as not estimable. Consequently, there is no recalculated estimate to compare numerically with the sponsor’s analysis. No discrepancy is flagged in the record. That does not fill in the missing comparative estimate or clarify which hypothesis the separate tests addressed.

The sponsor’s p-values should therefore be read as the registry’s reported test results, not as evidence that the interventions are equivalent or that their effects are the same. A formal non-inferiority or equivalence interpretation would require the analysis details and margin, which are not reported in the registry record.

12. Multiplicity, Missing Data and Analysis Populations

The registry identifies 26 outcome measures, 39 analyses, and 14 posted secondary outcomes. Its listed secondary outcomes cover lower-limb bone mineral density and content, triglycerides, HDL, LDL, total cholesterol, and the total-cholesterol-to-HDL ratio. The record does not explain how the outcome-measure count, analysis count, and posted secondary-outcome count relate to one another.

When a study assesses multiple outcomes or performs multiple analyses, the chance of obtaining at least one apparently notable result can increase. General statistical approaches to this issue include prespecifying a primary outcome, adjusting significance thresholds, or treating secondary results as exploratory. The registry does not report a multiplicity adjustment, a hierarchy of secondary hypotheses, or a statistical plan describing how multiple tests were handled. It is therefore not possible to determine whether the posted analyses account for multiplicity.

Missing-data procedures and analysis populations are not reported in the registry record. The overall enrollment is 29, while the primary outcome summaries list group sizes of 7.0 and 6.0. Those entries alone do not establish why the outcome groups have those sizes or what happened to other enrolled or randomized participants. They do not distinguish non-enrollment in an analysis from missing measurements, exclusions, or other explanations. No assumptions about attrition or outcome availability should be inferred from the difference.

The registry does not state whether the primary endpoint was analyzed by intention to treat, per protocol, or another approach. It also does not report imputation, complete-case analysis, sensitivity analyses, or reasons for missing measurements. These omissions matter because estimates can depend on which participants are included and on how missing values are handled. Without those details, the posted group summaries cannot be fully evaluated for selection effects or robustness.

13. Safety Results

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

Other (non-serious) adverse events

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

For serious adverse events, the registry reports 0 affected participants among 7 at risk in the Arm Cycling Ergometer group and 0 among 6 at risk in the FESLCE group. No serious adverse event terms are listed. These figures describe the registry’s reported counts; they do not establish that no events occurred outside the recorded follow-up or reporting process.

For other adverse events, the registry likewise reports 0 affected participants among 7 at risk for Arm Cycling Ergometer and 0 among 6 at risk for FESLCE. Death counts are not reported in the registry record. The duration and completeness of adverse-event surveillance, event definitions, and the method used to collect events are not reported, so the counts should not be read as a comprehensive account beyond the recorded information.

Small reported at-risk groups limit how much these zero counts can establish about safety. A zero count means no affected participants were recorded in the listed group; it does not rule out uncommon harms or provide a precise estimate of event risk. These figures are descriptive and do not support a comparison of safety between the exercise approaches.

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

The primary outcome summaries show negative mean change scores in both exercise groups. Under the registry’s definition of change as post-intervention minus baseline, this means that the group-average post-intervention percent body fat was lower than the group-average baseline value in each arm. The summaries do not demonstrate that exercise caused those changes, because the registry does not report a direct between-group estimate for the primary outcome.

The distinction between within-group change and a randomized comparison is important. A group’s change over time can reflect the assigned intervention as well as other influences. The comparative effect is the difference in outcomes between randomized groups, interpreted with its uncertainty and analysis assumptions. That comparative estimate and its confidence interval are not reported in the registry record. The separate p-values above 0.05 do not establish that the treatments are equivalent or that there is no difference.

The registry’s description presents a biological rationale involving energy expenditure, muscle mass, insulin sensitivity, glucose effectiveness, and lipid profiles. Those aims and hypotheses are not findings. The primary endpoint is percent body fat; it cannot stand in for results on the other measures. Although the registry lists secondary outcomes involving bone measures and lipids, their detailed results are not included in the registry record described for the primary endpoint.

The findings also do not establish whether either exercise schedule is suitable for a particular person. The registry summaries do not provide individual clinical context, and the analysis does not supply a precise comparative estimate. This interpretation is statistical rather than medical advice.

In short, the posted primary data describe mean change within each arm, with standard deviations and limited outcome-group sizes. They do not resolve the comparative question that motivates a randomized trial. The record lacks the between-group estimate, uncertainty interval, and information needed to evaluate the reported non-inferiority or equivalence labels. Conclusions should remain confined to the recorded summaries and their substantial interpretive limits.

15. Why This Trial Matters Statistically

This trial raises a useful statistical distinction: a study can report changes within randomized groups without reporting the randomized comparison that answers whether the groups changed differently. The primary endpoint has mean and standard deviation summaries for each exercise arm, but the registry does not provide an estimable two-arm result. Readers should not substitute separate within-group p-values for a comparative treatment estimate.

The analysis labels also illustrate why non-inferiority and equivalence require more than a non-significant test. Those questions depend on prespecified margins and an estimate precise enough to assess whether the plausible effects lie within the relevant bounds. The registry lists analyses under those labels, but the margin, tested parameter, and confidence intervals are not reported. The labels alone cannot establish equivalence.

The difference between overall enrollment and the primary-outcome group sizes is another reporting issue. The record does not explain the difference, and it does not identify the analysis population or missing-data procedures. Without that context, readers cannot determine how the endpoint summaries relate to the randomized population or assess the effects of missing measurements.

Finally, the posted safety counts are zero for the reported serious and other adverse events in both outcome arms, but the small at-risk groups and unreported surveillance details limit what can be concluded. These features make the record a useful example of separating descriptive results, comparative inference, and reporting completeness. The numerical group summaries are interpretable as summaries of recorded change; stronger comparative or safety claims require information the registry record does not report.

16. 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 the primary outcome is the absence of a reported between-group estimate and confidence interval. The group means and standard deviations describe each arm separately, but they do not quantify the comparative effect or its precision. The registry marks the two-arm continuous comparison as unavailable or not estimable.

The sponsor analysis entries are also difficult to evaluate. They report two-sided t-tests with p > 0.05 and label them non-inferiority or equivalence, but do not state the tested parameter, confidence interval, or margin. The entries do not establish a direct comparison between the exercise groups. A formal conclusion about non-inferiority or equivalence cannot be assessed from the reported information.

The outcome-group sizes listed for the primary endpoint are 7.0 and 6.0, while overall enrollment is 29. The registry does not explain the difference. It also does not report eligibility details, analysis population, missing-data handling, participant flow, adherence, or the reasons outcome data may not be represented in the group summaries. These gaps prevent assessment of how representative the analyzed observations are of the randomized study population.

The record lists multiple outcome measures and analyses but does not describe a multiplicity strategy or identify how secondary outcomes were prioritized. Detailed results for the listed secondary outcomes are not part of the primary endpoint details. The registry also does not provide enough information about adverse-event collection to determine the completeness of the safety record. These are reporting limitations; they do not establish that a particular analysis or event was omitted.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Exercise to Reduce Obesity in Spinal Cord Injury — NCT00270855.
• Registry record last updated 2017-11-17; status last verified 2017-10.
• Results first posted 2017-11-17.
• 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.

20. Record Summary

The completed randomized, parallel, unmasked trial compared Arm Crank Ergometry with Functional Electrical Stimulation Leg Cycle Ergometer exercise. Overall enrollment was 29. The primary endpoint was change in percent body fat from baseline to 16 weeks, defined as the post-intervention value minus baseline.

The registry reports mean changes of -1.83 for Arm Cycling Ergometer and -1.68 for FESLCE, with standard deviations of 2.72 and 0.98, respectively. The endpoint group sizes were 7.0 and 6.0. Separate two-sided t-test entries report p > 0.05, but the tested parameter and the information needed to assess the non-inferiority or equivalence labels are not reported. A between-group estimate and confidence interval are not reported in the registry record.

For the reported at-risk groups, no serious or other adverse events were recorded as affecting participants. Death counts, analysis populations, and missing-data procedures are not reported in the registry record.