This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Strength Training in Walking Tolerance in Intermittent Claudication Patients (NCT00879697), a randomized phase 3 study. The primary outcome is Total Walking Distance.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00879697 |
| Phase | Phase 3 |
| Condition | Peripheral Arterial Disease, Hypertension, Diabetes |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 34 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Sao Paulo |
| Results posted | Yes |
2. Clinical Question
Population
Patients with intermittent claudication. The registry also lists peripheral arterial disease, hypertension and diabetes among the conditions. It does not report the outcome population’s fuller eligibility criteria or describe which listed conditions applied to individual participants.
Intervention
Strength training. The description specifies whole-body exercises at sub-maximal intensity based on participants’ perceived effort. The summary describes 3 sets of 10 repetitions, and the arm description identifies 8 exercises.
Comparator
Walking training on a treadmill at sub-maximal intensity based on participants’ perceived effort. The summary describes 15 two-minute walking bouts interspersed with 2 minutes of rest. Both groups trained twice a week for 12 weeks at the same rate of perceived exertion.
Primary question
At 12 weeks, how did the reported mean maximal walking distance compare between the strength-training and walking-training groups? The endpoint is reported in meters. The posted group means are 618.0 for strength training and 572.0 for walking training; the registry’s own analysis reports an ANOVA result without a corresponding effect estimate or confidence interval.
The clinical question concerns a comparison between two exercise-training approaches, not a comparison with no training. Random allocation is recorded, but masking is listed as none. The registry describes the aim as analyzing the effects of strength training on walking capacity compared with walking training. It also lists peak VO2, walking economy, ankle brachial index, ischemic window and knee extension strength as measurements in the study summary. The registry record posts one outcome measure and one analysis, with Total Walking Distance identified as the primary outcome.
The result should be read as a comparison of group means at the specified endpoint, not as a reported change from baseline: baseline walking-distance results and a baseline-adjusted comparison are not reported in the registry record. The posted outcome values are means with standard deviations. The clinical question is therefore whether the registry’s available data support a clear difference in mean maximal walking distance at 12 weeks, and how uncertain that comparison remains.
3. Trial Design
The registry identifies this as a Phase 3, randomized, parallel-group study with no masking. It lists an enrollment of 34 and describes two behavioral interventions: strength training and walking training. The study status is completed. The recorded start is 2005-07 and the primary completion is 2008-08. The sponsor is University of Sao Paulo.
Participants were randomized to strength training or walking training. According to the study summary, both groups trained twice a week for 12 weeks and worked at the same rate of perceived exertion. Strength training is described as 3 sets of 10 repetitions of whole-body exercises. The arm description further specifies 8 exercises at sub-maximal intensity based on participants’ self-perceived effort. Walking training is described as 15 two-minute treadmill walking bouts, with 2 minutes of rest between bouts; its arm description also notes sub-maximal intensity guided by self-perceived effort.
The registry lists Total Walking Distance at 12 weeks as the primary outcome, measured in meters. It describes the measure as maximal walking distance and specifies that the posted summary is a mean with standard deviation. The reported outcome summaries include 15 participants in each group. The safety record separately gives 17 participants at risk in each group; the registry does not explain the difference between those reported counts.
Although randomization is recorded, the sequence-generation procedure, allocation concealment, and any stratification are not reported in the registry record. The specific protocol, original statistical analysis plan, and reasons for selecting the design are not reported in the registry record. Masking is explicitly listed as none, but whether outcome assessment was conducted independently is not reported in the registry record. These gaps limit assessment of how participants entered the groups and how the analysis was planned, beyond the information recorded in the results.
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: Seven patients did not present symptoms of claudication during the treadmill test, 5 presented electrocardiogram response suggestive of myocardial ischemia, 4 presented exercise tolerance limited by other factors than claudication, and 2 presented poorly controlled blood pressure. All these patients were not included in the study.
Overall Study
| Stage | Strength Training | Walking Training |
|---|---|---|
| STARTED | 17 | 17 |
| COMPLETED | 15 | 15 |
| NOT COMPLETED | 2 | 2 |
Reasons for not completing this period:
| Reason | Strength Training | Walking Training |
|---|---|---|
| Physician Decision | 2 | 2 |
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.
| Characteristic | Unit | Strength Training | Walking Training | Total |
|---|---|---|---|---|
| Participants analysed | 17 | 17 | 34 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 4 | 3 | 7 |
| Age, Categorical: >=65 years | Participants | 13 | 14 | 27 |
| Age, Continuous | years | 65.7 (SD 9.5) | 64.6 (SD 8.8) | 65.1 (SD 9.3) |
| Gender: Female | Participants | 5 | 7 | 12 |
| Gender: Male | Participants | 12 | 10 | 22 |
| Region of Enrollment: Brazil | participants | 17 | 17 | 34 |
| Total walking distance | meter | 618 (SD 282) | 572 (SD 231) | 595 (SD 244) |
6. Primary Endpoint
The registry lists the primary outcome as Total Walking Distance, measured over 12 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | meter |
| Endpoint classification | Continuous Endpoint |
Total Walking Distance is the registry’s primary endpoint. It measures the maximal distance a participant could walk, reported in meters, at the 12-week time point. The registry summarizes this continuous measure using a mean and standard deviation for each group. The reported mean is 618.0 for strength training and 572.0 for walking training.
As a general statistical point, a walking-distance measure can represent exercise performance in a way that is directly interpretable in the unit of distance. A group mean describes the average measured distance, while the standard deviation describes the spread of individual measurements around that mean. Neither alone gives the full picture: a mean difference estimates the contrast between group averages, and an uncertainty interval indicates how imprecisely that contrast is estimated.
The registry calls the endpoint maximal walking distance, but it does not report the detailed testing procedure, assessment conditions, or whether the measure was analyzed as a final value or as change from baseline. The posted results therefore support interpretation of the reported group summaries and their comparison, but not a more detailed account of how walking capacity was measured or how individual changes over time were handled.
7. Results Posted in the Registry
- Walking Training: mean 572.00 versus 618.00 on control; difference -46.00 (95% CI -230.48 to 138.48), standardized effect d = -0.18; z-test p = 0.625.
Mean difference: Walking Training
95% CI: -230.48 to 138.48
Recalculated from the posted summary statistics
8. Statistical Interpretation
The posted mean Total Walking Distance at 12 weeks is 618.0 meters in the strength-training group and 572.0 meters in the walking-training group. The unadjusted re-calculation from these summary statistics gives a mean difference of -46.0 meters for walking training compared with strength training. The direction indicates a lower observed group mean for walking training in these posted summaries. This is a descriptive comparison, not evidence by itself that the training approaches caused different outcomes.
The re-calculated interval extends from -230.5 to 138.5 meters. It includes zero, so the summary-statistic re-calculation does not rule out no difference between group means. It also spans values in both directions, meaning the posted summaries are compatible with a range that includes an advantage for either group. The unadjusted re-calculated p-value is 0.625. Taken together, these recalculations do not provide a precise estimate of the size or direction of a group difference.
The sponsor’s reported analysis is different: it lists an ANOVA with p <0.05 for the groups, but does not give the associated effect estimate, confidence interval, model details or analysis population. Because the discrepancy flag is true, the sponsor’s own analysis takes precedence. The sponsor’s result should not be replaced with the unadjusted re-calculation. The available record does not contain enough detail to reconcile the different p-values or determine whether the sponsor’s analysis adjusted for other factors or used a different analytic population.
The two findings answer the comparison through different reported information. The sponsor’s ANOVA indicates a reported statistical result below its stated threshold, while the re-calculation from the posted means and standard deviations has a p-value of 0.625 and a broad interval spanning zero. A p-value does not measure the size or clinical importance of an effect. Nor does a result below a threshold establish that the effect is large, precise, or clinically important. An effect estimate and uncertainty interval from the sponsor’s analysis would be needed to judge those features directly.
The reported group counts for the outcome are 15 in each arm, while the safety record lists 17 at risk in each arm. The registry does not explain why these counts differ. Baseline outcome values, missing-data handling, and the analysis population are not reported in the registry record. Consequently, the result cannot be interpreted as a documented baseline-adjusted change, nor can the record establish whether all randomized participants were included in the sponsor’s analysis. These limitations matter when interpreting both the sponsor’s test and the re-calculation.
Overall, the record reports a significant sponsor ANOVA result and a different unadjusted re-calculation based on summary statistics. The latter is imprecise and does not establish a clear difference. The sponsor’s analysis takes precedence, but the limited reporting makes its magnitude and precision difficult to assess. Neither result should be read as medical advice or as a conclusion about treatment benefit.
9. Statistical Methods Explained
There are two kinds of statistical information in the registry results. The arm summaries give a mean and standard deviation for each group. The sponsor’s reported analysis gives an ANOVA test and a p-value, but no effect estimate or confidence interval. Separately, an unadjusted re-calculation uses the posted group means and standard deviations to estimate a mean difference and its uncertainty. These are not interchangeable analyses: one is the sponsor’s reported test, and the other is a calculation based on the available summaries.
What does a mean difference describe?
For a continuous outcome such as walking distance, a mean difference describes the distance between the groups’ average results. The comparison is expressed in the same unit as the endpoint, meters. The re-calculated estimate is -46.0 meters for walking training compared with strength training, matching the order used in the comparison. The negative sign means that the observed mean in the walking-training group is lower than the observed mean in the strength-training group. It does not by itself establish that the interventions caused the difference.
The standard deviation describes variation among participant measurements within a group. The posted standard deviations are 282.0 meters for strength training and 231.0 meters for walking training. They are measures of spread among individual outcomes, not uncertainty in the group mean and not confidence limits for the difference. General statistical explanation: the standard error of a mean or contrast reflects uncertainty in an estimate, and depends on both variability and the amount of information available. A group mean can be estimated with more precision when the data contain less variation or more observations, all else being comparable.
What does the p-value tell the reader?
General statistical explanation: a p-value describes how unusual data at least as incompatible with a specified null model would be if that model were correct and the model’s assumptions held. It is not the probability that the null hypothesis is true, and it does not measure effect size, clinical importance, or the probability that a result will replicate. The re-calculated unadjusted p-value is 0.625. The sponsor reports an ANOVA p-value of <0.05. The analyses differ, and the registry does not provide enough detail to explain the difference. Because a discrepancy is flagged, the sponsor’s own analysis takes precedence.
ANOVA, or analysis of variance, is a general method for testing whether group means differ under a specified model. The registry identifies ANOVA as the sponsor’s method but does not report the model specification, test statistic, degrees of freedom, covariate adjustments, or analysis population. It is therefore not possible to determine from the registry record exactly how the reported test was constructed. The reported p-value alone also cannot show the size of the group contrast.
How should an interval estimate be read?
General statistical explanation: a confidence interval is a range of values compatible with the data under a method’s assumptions. It expresses uncertainty around an estimate; a wider interval indicates less precision than a narrower interval. The re-calculated interval runs from -230.5 to 138.5 meters and includes zero. It therefore covers the possibility of no mean difference as well as values on either side of zero. Its width cautions against treating the point estimate of -46.0 meters as a precise estimate of the underlying difference. The registry’s sponsor analysis lists a 95% confidence level but does not provide the interval limits or an effect estimate.
The confidence interval does not assign equal probability to each value in its range, nor does it guarantee that the true effect lies inside it. Its usual interpretation depends on the method and assumptions used to construct it. Details of the sponsor’s interval calculation are not reported in the registry record. The limits belong to the unadjusted re-calculation, not to the sponsor’s reported ANOVA.
Why can summary-statistic recalculation differ from the sponsor analysis?
General statistical explanation: analyses can produce different results when they use different populations, outcome definitions, baseline adjustments, variance assumptions, or model structures. A summary-statistic calculation generally cannot reproduce adjustments or participant-level handling that are not encoded in group means and standard deviations. The registry does not report whether any such choices explain this discrepancy. The posted information therefore supports description of the difference in results, but not a diagnosis of its cause.
The re-calculation is unadjusted and based on the posted summary statistics. It should not be treated as a substitute for the prespecified or sponsor-conducted analysis. The registry does not provide enough methodological detail to verify whether the sponsor’s ANOVA was prespecified or to reproduce it. The sponsor’s analysis takes precedence in accordance with the reported discrepancy, while the re-calculation remains useful as a transparent check of the displayed group summaries.
General statistical explanation: over-dispersion matters when observed variation exceeds what a model assumes. If a model underestimates variation, uncertainty can appear too small and statistical evidence too strong; if it overestimates variation, the reverse may occur. The registry does not report a count model or evidence of over-dispersion, and the primary outcome is continuous, so over-dispersion is not an identified issue for this reported comparison. More generally, all statistical tests rely on assumptions, and interpretation is strengthened when the model and diagnostic checks are reported.
10. Confidence Intervals and Precision
The precision of the unadjusted re-calculation is limited. Its mean difference is -46.0 meters, while its interval extends from -230.5 to 138.5 meters. Because zero lies within that range, the re-calculated interval does not exclude no difference. The limits also extend to values on either side of zero, so the direction and size of the underlying difference remain uncertain based on this calculation.
General statistical explanation: an interval communicates the uncertainty around an estimate rather than the range of individual participant outcomes. A broad interval indicates that the data do not pin down the group contrast closely. The standard deviations of 282.0 meters and 231.0 meters describe variability in the two observed groups, while the interval around the mean difference addresses uncertainty in the estimated contrast. These statistics answer related but distinct questions.
The sponsor’s analysis reports a 95% confidence level, but its interval limits and effect estimate are not reported in the registry record. The interval stated above is the one accompanying the unadjusted re-calculation; the registry does not specify a confidence level alongside those limits. Because the sponsor’s result differs from the re-calculation and the discrepancy is flagged, the sponsor’s own analysis takes precedence. Its reported p-value cannot replace an effect estimate and interval when judging precision.
The outcome count is 15 in each group, and the registry does not explain how those results relate to the enrollment or safety reporting. The original sample-size justification and the trial’s intended precision are not reported in the registry record. The observed uncertainty should therefore be interpreted from the posted re-calculation, without assuming that the trial was designed to detect a particular difference.
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.
| Effect to detect | Participants per arm, 80% power | Participants per arm, 90% power |
|---|---|---|
| 100% of the observed effect | 493 | 660 |
| 75% of the observed effect | 877 | 1,174 |
| 50% of the observed effect | 1,972 | 2,640 |
The sample-size table and curve are planning illustrations based on the observed effect, not reports of the trial’s original design. The figures are participants per arm, not total participants or total events. The rows describe planning for 100%, 75% and 50% of the observed effect. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is the stated proportion of the observed effect.
The 80% power column gives the planned participants per arm for a design that would have an 80% chance of detecting the specified effect under those assumptions, if that effect were the true one. The 90% power column describes the corresponding planning target for a 90% chance. These are prospective design calculations, not probabilities that the completed trial produced a correct result.
The table indicates that planning for 100% of the observed effect corresponds to 493 participants per arm for 80% power and 660 for 90% power. For 75% of the observed effect, the corresponding figures are 877 and 1,174 per arm. For 50% of the observed effect, they are 1,972 and 2,640 per arm. The curve represents the same general relationship: planning around a smaller effect requires more participants to achieve a given power target. Raising the power target also increases the required planning size.
This is not observed power. It does not show the probability that the trial detected a real effect, nor does it resolve the difference between the sponsor’s reported ANOVA and the unadjusted re-calculation. The original trial’s sample-size assumptions and justification are not reported in the registry record. These figures are illustrations tied to the observed re-calculated effect and the stated assumptions, not evidence about what the investigators planned or the study’s actual operating characteristics.
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 z1−α/2 = 1.960) and the desired power (z1−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
- Observed difference Δ = -46.000; pooled standard deviation σ = 257.764.
- n = 2 × (1.96 + 0.842)2 × 257.7642 / -46.0002 = 492.9, rounded up to 493 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 <- -46 # observed difference in means
sigma <- 257.764427336279 # 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(879697)
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 = 493 (80% power), 660 (90% power)
75% of observed effect: n per arm = 877 (80% power), 1,174 (90% power)
50% of observed effect: n per arm = 1,972 (80% power), 2,640 (90% power)
power.t.test: 493.9
Simulated power at n = 493 per arm: 0.800 (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. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| ANOVA | not reported | < 0.050 |
The sponsor’s reported analysis is an ANOVA comparing the groups, with a reported p-value of <0.05. The registry does not report its effect estimate, confidence-interval limits, model details, or analysis population. The result therefore conveys a reported statistical test but does not show the magnitude or precision of the sponsor’s estimated difference.
The unadjusted re-calculation uses the posted group means and standard deviations. It estimates a mean difference of -46.0 meters for walking training compared with strength training, with an interval from -230.5 to 138.5 meters and a p-value of 0.625. This calculation does not reproduce the sponsor’s reported result. The registry flags a discrepancy, so the sponsor’s own analysis takes precedence; the re-calculation is not a replacement for it.
The record does not explain the discrepancy. Differences in analysis populations or model choices can generally affect results, but the registry does not establish that any particular factor caused this difference. Without the analysis details or participant-level data, the sponsor’s ANOVA cannot be independently reconstructed from the posted summaries. The available information supports reporting both results and their limitations, not selecting an unreported explanation for why they differ.
14. Multiplicity, Missing Data and Analysis Populations
The registry posts one outcome measure and one analysis. Total Walking Distance is identified as the primary outcome, and the study summary lists other measurements, including peak VO2, walking economy, ankle brachial index, ischemic window and knee extension strength. Results for secondary outcomes are not posted in the registry record. The relationship between the listed measurements and any planned hypothesis tests is not reported.
Multiplicity arises when several outcomes, time points, subgroups, or statistical tests are examined. General statistical explanation: testing many hypotheses can increase the chance of at least one apparently unusual result, unless the analysis plan addresses that issue. The registry does not report a multiplicity strategy, a hierarchy of outcomes, or whether any adjustment was used. Since secondary results are not posted, the extent of testing cannot be assessed from the registry record.
Missing-data procedures are also not reported in the registry record. The outcome summaries list 15 participants in each group; the safety record separately lists 17 at risk in each group. The registry does not explain the difference, report missing outcome counts, or state whether participants were excluded from the primary analysis. It does not describe imputation, sensitivity analyses, or how incomplete follow-up was handled. Therefore, the impact of missing outcome data cannot be evaluated.
The analysis population is not reported in the registry record. Randomization is recorded, but the record does not say whether the analysis followed intention-to-treat principles, included only participants who completed training, or used another population. The protocol, original analysis plan, and details of any interim analyses are not reported in the registry record. The number of posted analyses does not establish what was planned or conducted beyond what is recorded.
These omissions affect interpretation of the sponsor’s ANOVA as well as the re-calculation. In particular, the available summaries do not establish whether the compared groups retained their randomized composition or whether the sponsor adjusted for baseline variables. The results should be read with these reporting limits in mind rather than assuming a particular missing-data or multiplicity approach.
15. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Strength Training | 0 | 17 | 0.0% |
| Walking Training | 0 | 17 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 3.5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Strength Training | 2 of 17 |
| Walking Training | 2 of 17 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Strength Training | Walking Training |
|---|---|---|---|
| Inguinal hernia | Nervous system disorders | 1 of 17 | 0 of 17 |
| Gastrointestinal problems | Gastrointestinal disorders | 1 of 17 | 0 of 17 |
| Diagnose Lung cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0 of 17 | 1 of 17 |
| Diagnose aneurysm | Vascular disorders | 0 of 17 | 1 of 17 |
The serious adverse event record lists 0 serious events among 17 participants at risk in the strength-training group and 0 among 17 at risk in the walking-training group. It lists 2 other adverse events among 17 at risk in each group. No serious-event terms are listed. Death counts are not reported in the registry record.
These figures are descriptive counts within the registry’s stated at-risk groups. They do not establish that the groups had identical safety profiles, and the record does not provide event descriptions, severity details for the other events, timing, or an assessment of whether events were related to training. The registry also does not explain how the at-risk counts relate to the outcome-analysis counts.
General statistical explanation: event counts can be informative but are not, by themselves, a complete comparison of safety. Interpretation depends on how events were defined, how they were collected, the time under observation, and how missing reports were handled. Those details are not reported in the registry record. These posted figures should therefore be read narrowly as the adverse-event counts recorded, not as a comprehensive estimate of risk.
16. What the Result Does, and Does Not, Mean
The registry reports group means for maximal walking distance at 12 weeks: 618.0 meters for strength training and 572.0 meters for walking training. The sponsor reports an ANOVA result with p <0.05, but does not report the associated effect estimate or confidence interval. The unadjusted re-calculation from the posted summaries gives a mean difference of -46.0 meters, an interval from -230.5 to 138.5 meters, and a p-value of 0.625. The discrepancy is flagged, and the sponsor’s own analysis takes precedence.
The sponsor’s p-value indicates a reported statistical result under its analysis, but without an effect estimate and uncertainty interval its magnitude and precision cannot be evaluated from the registry record. The unadjusted re-calculation is not precise enough to exclude zero and is not a substitute for the sponsor’s analysis. Neither result alone establishes clinical importance. The registry does not report a threshold for a meaningful difference in walking distance.
The results also do not establish how much participants changed from their starting values. Baseline walking-distance data and a change-from-baseline analysis are not reported in the registry record. The record does not explain the different participant counts in the outcome and safety summaries, or report missing-data handling and the analysis population. It is therefore not possible to determine from the posted record whether the primary comparison included all randomized participants.
In general, randomized comparisons can help assess differences between assigned groups, but interpretation depends on how the trial was conducted and analyzed. Here, the record does not describe sequence generation, allocation concealment, or the sponsor’s model in sufficient detail to evaluate those features fully. No masking is recorded. The reported result should be understood as a limited statistical account of the comparison, not as medical advice or a definitive statement that either training approach works or does not work.
The study’s summary describes a 12-week training period and lists several physical-fitness measurements, but only the primary walking-distance outcome has posted results in the registry record. The findings therefore do not provide a complete account of all measured outcomes. They also do not, on their own, establish longer-term effects beyond the stated endpoint or outcomes beyond those recorded.
17. Why This Trial Matters Statistically
This trial illustrates why a p-value should not be read without an effect estimate and a measure of uncertainty. The sponsor reports an ANOVA p-value of <0.05, while the unadjusted re-calculation from the posted means and standard deviations gives a p-value of 0.625 and an interval that includes zero. The discrepancy is explicitly flagged, so the sponsor’s own analysis takes precedence, but its missing estimate and interval leave the size and precision of that result unclear.
It also shows the importance of distinguishing a group mean from a group contrast. The means describe the observed average walking distance in each arm; the re-calculated difference puts the contrast into meters. Standard deviations describe variation among observations, while an interval describes uncertainty around the contrast. These quantities answer different questions and should not be treated as substitutes for one another.
The registry’s reporting gaps affect interpretation as much as the numeric result. There is no reported account of the sponsor’s analysis population, missing-data procedures, baseline adjustment, or multiplicity approach. The outcome summaries and safety at-risk counts also differ, without an explanation in the record. These omissions make it difficult to assess whether the reported comparison follows the randomized groups as intended or to reproduce the sponsor’s analysis.
Finally, the sample-size illustrations demonstrate how planning depends on the effect targeted: smaller effects require larger planned group sizes under the stated assumptions. Those calculations are not evidence of observed power and do not reveal the original design rationale. Taken together, the record is a useful example of separating reported findings, recalculated summaries, planning illustrations, and unanswered methodological questions.
18. 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’s outcome reporting has limited detail. It identifies Total Walking Distance as maximal distance at 12 weeks, but does not describe the testing protocol, baseline values, or whether the posted values represent final measurements or another endpoint construction. The registry does not report a baseline-adjusted analysis or change-from-baseline result.
The posted outcome summaries list 15 participants in each group, while the safety record lists 17 at risk in each group. The registry does not explain this difference or state how many randomized participants were included in the primary analysis. Missing-data methods and the analysis population are not reported, so the effect of incomplete outcome data cannot be assessed.
The sponsor’s reported ANOVA has a p-value but no effect estimate, confidence interval, model specification or analysis population. The unadjusted re-calculation differs, and the registry does not explain the reason. The discrepancy flag means the sponsor’s analysis takes precedence, but the record does not provide enough detail to reproduce or evaluate that analysis fully. Randomization is recorded, while sequence generation and allocation concealment are not reported. Masking is listed as none.
The record posts results for the primary outcome but not for secondary measurements listed in the study summary. It does not report a multiplicity plan, missing-data procedures, interim analyses, or the original sample-size justification. The sample-size illustrations are based on the observed re-calculated effect and should not be treated as the study’s original design plan.
The safety record provides counts but does not report event descriptions, timing, relatedness, or death counts. The registry also does not give a detailed account of follow-up beyond the primary endpoint. These limitations restrict interpretation to the recorded summaries and analysis statements; they do not establish what may have been documented elsewhere.
19. Related Tutorials
20. Related Statistical Calculators
21. Sources
- ClinicalTrials.gov: Strength Training in Walking Tolerance in Intermittent Claudication Patients — NCT00879697.
- Registry record last updated 2016-12-15; status last verified 2016-10.
- Results first posted 2009-04-10.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
22. Record Summary
NCT00879697 is recorded as a completed, randomized, parallel-group Phase 3 study with no masking and an enrollment of 34. The sponsor is University of Sao Paulo. The recorded start is 2005-07, and primary completion is recorded as 2008-08.
The study compared strength training with walking training in patients with intermittent claudication. Both groups trained twice a week for 12 weeks at the same rate of perceived exertion. The primary outcome is Total Walking Distance at 12 weeks, reported as mean maximal distance in meters.
The posted means are 618.0 meters for strength training and 572.0 meters for walking training, with 15 participants reported in each outcome group. The sponsor reports an ANOVA p-value of <0.05 but no effect estimate or interval. An unadjusted re-calculation differs; because the discrepancy is flagged, the sponsor’s own analysis takes precedence. The registry does not report enough detail to resolve that discrepancy or fully assess the analysis.