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 Exercise Trial in Chronic Kidney Disease (NCT01462097), a randomized na study. The primary outcome is Change in Peak Aerobic Capacity.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01462097 |
| Phase | NA |
| Condition | Chronic Kidney Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 99 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Maryland, Baltimore |
| Results posted | Yes |
2. Clinical Question
Population
Older adults with chronic kidney disease who are not requiring dialysis are the population described in the study summary. The primary outcome population is participants with a VO2peak measurement at at least one time point. The registry record does not give further eligibility details in the registry record for this analysis.
Intervention
The intervention is aerobic exercise training over 12 months. The registry describes treadmill walking and strength training, and the study summary refers to aerobic and resistance exercise training. The exercise program is behavioral rather than a medication intervention.
Comparator
The comparison group receives health education over 12 months. The listed topics include safe travel, age-appropriate preventive screenings, reliable health information, and chronic kidney disease. The registry record describes a randomized, parallel-group comparison.
Primary question
The primary question concerns change in peak aerobic capacity, measured as VO2peak in ml/kg/min, across baseline, six months, and 12 months. Higher VO2peak indicates better aerobic capacity. The registry record does not report a single contrast between exercise and health education, nor an effect estimate, confidence interval, or p-value for this outcome.
This framing identifies the intervention, comparator, population, and outcome without implying that a difference was observed. The clinical question is about the outcome trajectory during the study period, but the registry record does not state whether the principal comparison was between groups at a particular visit, between changes over time, or based on another summary of the repeated measurements. It also does not report the study’s detailed eligibility rules or the analysis population beyond the primary-outcome population description.
3. Trial Design
The study is listed as a randomized, single-masked, parallel trial. Participants were assigned to aerobic exercise or health education. The registry lists the condition as chronic kidney disease and the sponsor as the University of Maryland, Baltimore. The phase is listed as not applicable.
The intervention descriptions identify a 12-month program of treadmill walking and strength training in the exercise group, and a 12-month program of health education in the comparator group. The health education topics include safe travel, preventive screenings, sources of reliable health information, and chronic kidney disease. The study summary describes the exercise program as aerobic and resistance training and says that the target population is older adults with chronic kidney disease who do not require dialysis.
The registry lists enrollment as 99. Its brief summary describes a study in 120 older adults. These are different enrollment figures in the registry record; it does not explain the relationship between them. The listed study start is 2012-03, the primary completion date is 2017-10-31, and the status is completed.
“Single” masking does not identify who was masked. The masked party or parties are not reported in the registry record. Details such as the randomization procedure, allocation concealment, adherence monitoring, and the exact schedule of study visits beyond the stated outcome time points are also not reported in the registry record. The arm descriptions are incomplete in the registry record, so further details of the intervention schedule should not be inferred from them.
The primary outcome is change in peak aerobic capacity, with measurements listed at baseline, six months, and 12 months. The registry also lists change in physical function and the number with an SPPB score <10 out of a maximum of 12 among secondary outcomes. The registry record lists four outcome measures, but no analysis is listed.
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
| Stage | Aerobic Exercise | Health Education |
|---|---|---|
| STARTED | 49 | 50 |
| 6 Month | 35 | 37 |
| COMPLETED | 30 | 38 |
| NOT COMPLETED | 19 | 12 |
Analysis population for the primary outcome, as defined in the registry: Participants with complete V02peak at \>=1 time point
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 | Aerobic Exercise | Health Education | Total |
|---|---|---|---|---|
| Participants analysed | 49 | 50 | 99 | |
| Age, Continuous | years | 67.9 (SD 7.7) | 68.1 (SD 8.8) | 68.0 (SD 8.2) |
| Sex: Female, Male: Female | Participants | 15 | 10 | 25 |
| Sex: Female, Male: Male | Participants | 34 | 40 | 74 |
| Race/Ethnicity, Customized: African-American | Participants | 27 | 34 | 61 |
| Race/Ethnicity, Customized: Caucasian | Participants | 18 | 13 | 31 |
| Race/Ethnicity, Customized: Other | Participants | 4 | 3 | 7 |
| Region of Enrollment: United States | participants | 49 | 50 | 99 |
| Estimated glomerular filtration rate (eGFR) | ml/min/1.73m^2 | 34.1 (SD 9.5) | 32.6 (SD 11.4) | 33.3 (SD 10.5) |
| Hemoglobin (g/dl) | g/dL | 12.5 (SD 1.6) | 12.3 (SD 1.7) | 12.4 (SD 1.6) |
| Body Mass Index (kg/m2) | kg/m2 | 30.3 (SD 7.2) | 31.8 (SD 5.8) | 31.1 (SD 6.5) |
| Self-reported Moderate-vigorous physical activity | minutes/week | 72 (SD 126) | 90 (SD 174) | 78 (SD 150) |
| Coronary Artery Disease | Participants | 16 | 13 | 29 |
| Diabetes | Participants | 30 | 28 | 58 |
| Hypertension | Participants | 44 | 48 | 92 |
| Heart Failure | Participants | 6 | 4 | 10 |
| Peripheral vascular disease | Participants | 3 | 6 | 9 |
| Chronic Obstructive Pulmonary Disease (COPD) | Participants | 5 | 8 | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Peak Aerobic Capacity, measured over Baseline, 6 months, 12 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ml/kg/min |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in peak aerobic capacity, measured as VO2peak in ml/kg/min. VO2peak is the highest oxygen uptake reached during an exercise test; in this record it is assessed using a graded exercise treadmill test with a modified Balke protocol. The registry states that higher values indicate better aerobic capacity.
Peak aerobic capacity is used as an objective measure of capacity during exertion. In a trial of exercise training, it can describe a physiological aspect of exercise performance, while the separately listed physical-function outcomes address other dimensions of function. The endpoint is recorded at baseline, six months, and 12 months, which makes the outcome longitudinal rather than a single measurement at one visit.
The primary-outcome population is described as participants with a VO2peak measurement at at least one time point. The registry record does not state how missing measurements were handled or how change was calculated. It also does not define a single contrast across the listed time points. Although the endpoint and its direction are specified, the registry record does not report group means, changes, a between-group effect estimate, its uncertainty, or a p-value. Consequently, the endpoint definition alone does not establish the size or precision of any difference between the study groups.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a relevant comparison: aerobic exercise training versus health education in older adults with chronic kidney disease who do not require dialysis. It also specifies peak aerobic capacity as the primary outcome and gives its measurement scale, testing method, direction, and assessment times. These details describe what the trial set out to measure, but they do not provide the result of the primary comparison.
The primary outcome has multiple time points, and the record indicates that it was not reduced to a single comparison. No numerical outcome results are included in the registry record for this analysis. In particular, there is no reported group mean, change from baseline, between-group estimate, confidence interval, or p-value. Without those quantities, the direction, magnitude, and statistical precision of the primary outcome cannot be characterized from the registry record. The missing result should not be replaced with an assumed test or an interpretation based on the study’s stated aims.
The record lists change in physical function and the number of participants with an SPPB score <10 out of 12 as secondary outcomes. It does not provide numerical results for these outcomes either. The record lists four outcome measures and zero analyses. That listing does not establish that no analyses were performed; it means the registry record does not list analyses in the registry record.
Enrollment is listed as 99, while the brief summary describes 120 planned participants. The registry record does not explain this difference, so neither figure should be treated as a verified count of participants analyzed. The primary-outcome population is described by availability of a VO2peak measure at at least one time point, but the record does not say how many participants met that description or how participants with missing visits were handled.
Safety entries include counts of participants affected by serious adverse events and deaths in each group. These are descriptive safety figures, not estimates of the primary aerobic-capacity outcome. The registry record does not provide the definitions, follow-up details, or statistical comparisons needed to interpret those figures as evidence of a causal safety difference.
The appropriate reading is therefore limited: the record documents a completed randomized trial and its intended comparison and outcomes, but it does not report the primary result needed to assess the observed difference or its precision. The absence of a reported result is not evidence that the groups were alike, nor evidence that they differed.
9. Statistical Methods Explained
Statistical methods clarify how an outcome is summarized, how groups are compared, and how much uncertainty surrounds an estimate. The registry record gives some design and outcome details, but it does not report the method used for the primary outcome analysis. The explanations below describe general statistical concepts; they should not be read as a description of an analysis that the registry confirms was performed.
What does a mean represent?
The primary outcome is a continuous measure, and the registry identifies the summary parameter as a mean with standard deviation. A mean describes the center of a group’s measurements. A standard deviation describes how spread out individual measurements are around that group mean. The standard deviation is not the same as the uncertainty in a group mean or in a difference between groups. A confidence interval is commonly used to describe uncertainty in an estimated effect; no confidence interval for the primary outcome is reported in the registry record.
Why does the timing matter?
VO2peak is measured at baseline, six months, and 12 months. Repeated measurements from the same participant are generally related rather than independent. A method that analyzes repeated observations may account for that within-participant relationship and use measurements across visits, while a comparison at a single visit or a change-score analysis answers a different question. These approaches can produce estimates with different interpretations. The registry record does not say which approach was used, whether the main contrast was a difference in change, a comparison at a visit, or another longitudinal summary, or how the time pattern was modeled.
What does randomization contribute?
Random assignment is intended to make the groups comparable, on average, with respect to measured and unmeasured characteristics at the point of assignment. It supports interpretation of a between-group contrast, but it does not ensure that every baseline feature is identical, nor does it remove uncertainty from a study estimate. The registry confirms randomization and a parallel design, but details of sequence generation, concealment, and the analysis population are not reported in the registry record.
What does masking mean?
The trial is listed as single-masked. Masking can reduce the influence of expectations on assessments or other parts of trial conduct, depending on who is masked and what information is concealed. The record does not identify the masked party or explain which assessments, if any, were masked. The intervention types are different in nature, so the registry’s label alone is not enough to determine how masking operated in practice.
Why can over-dispersion matter?
For outcomes that count events, variation can be greater than a simple probability model expects. This is called over-dispersion. If it is ignored, standard errors and confidence intervals can be too small, making an estimate appear more precise than it is. For continuous outcomes such as VO2peak, the specific issue is not automatically over-dispersion; the analyst instead needs a model appropriate to the measurement distribution and the repeated-observation structure. The registry record does not report distributional checks or modeling assumptions.
What do p-values and confidence intervals add?
A p-value describes how incompatible the observed data are with a specified null model, under the assumptions of the chosen analysis. It is not the probability that the null hypothesis is true, nor does it describe the size or practical importance of an effect. A confidence interval gives a range of values compatible with the estimate and its uncertainty under the model. Neither is reported for the primary comparison in the registry record, so statistical significance and precision cannot be assessed.
What does the planning illustration mean?
The registry describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The planning approach considers effects stated as fractions of the observed effect. These assumptions describe a planning exercise, not the trial’s own documented design justification. Sample-size figures from such an illustration are planning quantities, not observed power. The registry record does not report the trial’s sample-size justification or a statistical analysis plan.
None of these general methods can be assigned to this trial without a registry description of the analysis. The record does not report a model, a treatment-effect estimate, a confidence interval, a p-value, or procedures for missing data. Therefore, explanations of possible analysis choices cannot substitute for the missing primary-outcome result.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when researchers assess more than one outcome, comparison, time point, or analysis. If many statistical tests are conducted, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that issue. The registry lists a primary outcome measured at baseline, six months, and 12 months, along with secondary outcomes for physical-function change and SPPB score <10 out of 12. It lists four outcome measures. The record does not identify a multiplicity adjustment, a hierarchy among secondary outcomes, or a prespecified primary contrast across time points. Those details are not reported in the registry record.
The primary-outcome population is defined as participants with a VO2peak measurement at at least one time point. That description does not establish whether the analysis followed intention-to-treat principles, used all available measurements, or included only participants with a particular pattern of follow-up. The record does not report the number of missing measurements, reasons for missingness, or a missing-data method. It also does not state whether sensitivity analyses were conducted.
Missing data can affect both the precision and interpretation of an estimate, especially when the reasons data are unavailable are related to outcomes or group assignment. Methods such as complete-case analysis, likelihood-based longitudinal models, or imputation have different assumptions. These are general options, not methods confirmed for this trial. Without information on missingness and analysis populations, the primary-outcome population cannot be equated with all randomized participants.
The registry lists zero analyses. This does not establish that analyses were not conducted; it means that analysis information is not listed in the registry record. A statistical analysis plan, interim-analysis details, and the approach to multiplicity are not reported in the registry record.
11. 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 |
|---|---|---|---|
| Aerobic Exercise | 21 | 49 | 42.9% |
| Health Education | 34 | 50 | 68.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Aerobic Exercise | 1 of 49 |
| Health Education | 2 of 50 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Aerobic Exercise | 30 of 49 |
| Health Education | 31 of 50 |
Most frequent serious adverse event terms
| Event term | Organ system | Aerobic Exercise | Health Education |
|---|---|---|---|
| All SAEs | General disorders | 21 of 49 | 34 of 50 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Aerobic Exercise | Health Education |
|---|---|---|---|
| All AEs | General disorders | 30 of 49 | 31 of 50 |
Serious events with the highest arm-level rate: all saes (68.0%).
The serious adverse event entries list 21 participants affected among 49 at risk in the Aerobic Exercise group and 34 affected among 50 at risk in the Health Education group. The death counts are 1 and 2, respectively. These are registry counts, not estimates of the primary VO2peak effect. The registry also lists “All SAEs” at 68.0%, but does not clarify the denominator or how that percentage relates to the group-specific counts.
Counts of participants affected do not show how many events each participant experienced, the timing or duration of events, or their severity beyond the serious-event classification. The registry record does not provide event definitions, causal attribution, exposure-adjusted rates, or a statistical comparison for these safety figures. The counts should therefore be read descriptively rather than as proof of a difference between groups.
The figures also do not resolve the difference between the listed enrollment of 99 and the 120 participants described in the brief summary. The registry record does not explain which participants contributed to these safety summaries or how follow-up affected the at-risk counts. No conclusions about safety beyond the recorded counts are warranted from these entries alone.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, parallel-group trial compared aerobic exercise training with health education in older adults with chronic kidney disease. It specifies a primary outcome that has a clear measurement scale and direction: VO2peak in ml/kg/min, with higher values indicating better aerobic capacity. It also provides the intended assessment times and describes the intervention and comparator.
What the record does not establish is the observed primary-outcome difference. No group-level VO2peak values, changes, effect estimate, confidence interval, or p-value are reported in the registry record for this analysis. Thus, the direction and size of any difference, and the precision of an estimate, are unknown from the registry record. A completed-trial status and a stated study objective do not supply those missing results.
The record’s secondary outcomes and safety counts add context about what was registered, but they cannot stand in for the primary comparison. The listed serious adverse event and death counts do not provide an estimate of aerobic-capacity change. Likewise, the sample-size planning description does not describe observed power or establish what the trial’s results show.
The registry lists enrollment as 99 and describes 120 participants in its brief summary. Since the relationship between those figures is not explained, they should not be combined or interpreted as a precise analysis count. The primary-outcome population description also does not show how many participants contributed measurements or how missing values were treated.
In statistical terms, the available record supports a description of the research question and some design features, but not an assessment of effect magnitude or uncertainty. It cannot support a conclusion that exercise and education produced the same outcome, nor a conclusion that they produced different outcomes. The distinction is important: a missing result is not a null result. Interpretation of efficacy or comparative safety would require the relevant outcome estimates and their analysis details, which are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically interesting because its primary outcome is measured repeatedly during a randomized comparison. Repeated VO2peak measurements can describe change over time, but the scientific meaning of the result depends on the chosen contrast: a between-group difference at a visit, a difference in change, or a broader summary of trajectories may answer different questions. The registry specifies baseline, six months, and 12 months but does not state which contrast was primary.
The study also illustrates why outcome definitions and analysis populations matter. The registry identifies VO2peak as the primary outcome and describes the population using availability of a measurement at at least one time point. That is useful context, but it does not say how incomplete follow-up was handled or whether all randomized participants were included. Those choices can affect estimates and their uncertainty.
There are multiple registered outcome measures, including physical function and an SPPB threshold outcome. Considering multiple outcomes and time points raises questions about prespecification and multiplicity. The registry record does not report an analysis plan or a multiplicity strategy, so readers cannot determine how those issues were handled.
Finally, the record shows that design information and results information are distinct. Randomization and a completed status describe important features of the study, while the absence of a reported primary comparison leaves the central statistical question unanswered. The listed sample-size planning assumptions are not a substitute for an observed estimate or its precision. For this record, the statistical contribution is therefore chiefly the definition of the intended comparison and the limits on what can be concluded without posted outcome analyses.
14. 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 has important gaps for interpreting this particular trial. It does not report numerical results for the primary outcome, despite identifying VO2peak as the primary endpoint and listing measurements across baseline, six months, and 12 months. There is no primary effect estimate, confidence interval, or p-value, and the record indicates that the outcome was not reduced to a single comparison. The direction and precision of the primary result therefore cannot be assessed.
Enrollment is listed as 99, whereas the brief summary describes 120 participants. The registry record does not reconcile these figures. The arm descriptions are incomplete, so the full intervention schedules cannot be reconstructed from the record. Although masking is listed as single, the masked party is not identified.
There is also no reported statistical analysis plan, model specification, analysis population, missing-data approach, or multiplicity strategy. The primary-outcome population description does not report how many participants contributed data or whether the analysis included all randomized participants. These omissions limit assessment of bias, precision, and the relationship between the registered question and any analyses.
The safety information is limited to counts and a listed “All SAEs” percentage. Event definitions, attribution, timing, and a statistical comparison are not reported in the registry record. These limitations are specific to the available record and do not establish that the study lacked these procedures or analyses; they mean that they cannot be assessed from the information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Exercise Trial in Chronic Kidney Disease — NCT01462097.
- Registry record last updated 2023-01-25; status last verified 2023-01.
- Results first posted 2023-01-25.
- 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.
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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed randomized, single-masked, parallel trial sponsored by the University of Maryland, Baltimore. It compares 12 months of aerobic exercise training with health education in older adults with chronic kidney disease who do not require dialysis. Enrollment is listed as 99, while the brief summary describes 120 participants; the record does not explain the difference.
The primary outcome is change in VO2peak, measured in ml/kg/min at baseline, six months, and 12 months. Higher values indicate better aerobic capacity. The record lists secondary physical-function outcomes and safety counts, but does not report a single primary-outcome comparison, numerical efficacy results, or analysis details. Thus, the registry record documents the trial question and selected design features but does not establish the magnitude or precision of the primary result.