Exercise Training in Heart Failure: Changes in Cardiac Structure and Function: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Exercise Training in Heart Failure: Changes in Cardiac Structure and Function (NCT02275819), a non-randomized na study. The primary outcome is Change in Left Ventricular Systolic Function..

2. Clinical Question

The study is concerned with cardiac structure and function in heart failure. Its description identifies filling ability, pumping strength, and the heart’s ability to rebuild as areas of interest. The listed primary outcome focuses on change in left ventricular ejection fraction, a measure of systolic function. That endpoint addresses only one part of the broader research question; the record does not give enough detail to determine how the other areas of interest were measured or analyzed.

The clinical question is exploratory rather than a clearly specified randomized comparison. Allocation is listed as non-randomized, and the arm descriptions do not establish how participants entered each group. Therefore, any difference between groups would need to be interpreted in light of potential differences that existed before the interventions. The registry record does not report those baseline group characteristics or a numerical primary outcome result.

3. Trial Design

NCT02275819 is listed as a completed, non-randomized, parallel study sponsored by the VA Office of Research and Development. Enrollment is recorded as 11. The study start is 2016-06-06, and primary completion is 2019-04-23. The phase is listed as NA, and masking is listed as none.

The named intervention is Exercise. The control arm description says participants will not receive an exercise intervention. The intervention-group description says that 2 groups will receive 2 different types of therapy, exercise or Inspiratory Muscle Therapy. These descriptions leave the relationship between the named intervention, the groups, and the two therapies unclear. The number assigned to each group and the process used to assign participants are not reported in the registry record. The record therefore does not support treating the control arm as a randomized or otherwise balanced comparator.

The primary outcome is change in left ventricular systolic function, expressed as percent LVEF. The stated timeframe is baseline and endpoint at 3-5 months. The outcome is described as a mean with standard deviation, but the corresponding numerical group results are not reported in the registry record.

The registry record lists 5 outcome measures and 5 analyses, but does not identify the full analysis plan, explain how the listed analyses relate to the outcomes, or specify which other outcomes were designated primary or secondary. It also does not report a sample-size justification, participant flow, or details of the analysis population. The completed status indicates the trial is recorded as finished; it does not by itself supply the missing outcome estimates or explain how the study was conducted.

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: 13 participants were consented but only 11 were enrolled. Two were excluded from randomization due to subsequent echocardiogram or pulmonary function screening not meeting enrollment criteria. One was withdrawn after enrollment due to increasing symptoms of heart failure. Due to the small number of participants enrolled in each of the active intervention arms we combined participants from both intervention groups and analyzed against the controls.

Overall Study

Reasons for not completing this period:

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 Left Ventricular Systolic Function., measured over Baseline and endpoint at 3-5 months.

The primary endpoint is change in left ventricular ejection fraction, identified in the record as change in left ventricular systolic function and measured in percent LVEF. The stated assessment points are baseline and endpoint at 3-5 months. The record specifies a mean and standard deviation as the summary format, but numerical measurements, a mean change, and its uncertainty are not reported in the registry record.

In general, left ventricular ejection fraction describes the share of blood in the left ventricle that is ejected with a heartbeat. It is used as an indicator of systolic function, or the heart’s pumping function. A change in this measure can therefore address whether the measured pumping function differs between the stated assessment points. It does not, by itself, describe every aspect of cardiac structure, filling, symptoms, or functional capacity.

For a change endpoint, interpretation depends on knowing how the change was calculated, which participants contributed measurements at both time points, and how missing measurements were handled. Those details are not reported in the registry record. The endpoint’s description identifies the intended measure and timeframe, but without numerical results it is not possible to assess the direction or size of the observed change, or how precisely it was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is continuous: left ventricular ejection fraction is expressed as percent LVEF, and the registry specifies a mean and standard deviation. General statistical explanations below describe how these methods are commonly interpreted. They do not establish which analyses the investigators actually performed; detailed analysis methods are not reported in the registry record.

What a mean and standard deviation describe

In general, a mean summarizes the center of a set of measurements. A standard deviation describes how spread out individual measurements are around that mean. They answer different questions: the mean concerns the typical measured value, while the standard deviation concerns variation among observations. Neither statistic alone describes uncertainty in the estimated mean. A confidence interval is commonly used to express that uncertainty, but no confidence interval for the primary endpoint is reported in the registry record.

For a change outcome, a mean change would summarize the average difference between measurements at baseline and the endpoint, if the same participants contributed data at both assessments. The registry record states the assessment timeframe but does not say whether the reported summary, if any, would be based on within-participant changes, endpoint values adjusted for baseline, or another approach. It also does not report the underlying measurements or numerical summary.

Why allocation matters

In general, random allocation helps make groups comparable, on average, with respect to both measured and unmeasured characteristics at the start of a study. This study is listed as non-randomized. Non-randomized allocation can leave differences between groups that are related to the outcome, so a group contrast may reflect those differences as well as any intervention-associated change. Statistical adjustment can address measured characteristics under appropriate conditions, but it cannot guarantee removal of confounding from characteristics that were not measured or modeled.

The registry record does not describe the allocation process, baseline characteristics, or any adjustment model. It is therefore not possible to assess whether the group comparison accounted for potential differences. The parallel model indicates that the record describes groups followed in parallel, but that label does not resolve the lack of randomization or explain the precise treatment contrasts.

How to read a confidence interval and test result

In general, a confidence interval gives a range of estimates compatible with the data and the method used, and indicates statistical precision. A narrower interval indicates greater precision than a wider interval, all else being equal. A p-value, when reported, describes how unusual the data would be under a specified null model; it does not measure the probability that an intervention works or the importance of an effect. The registry record does not report a confidence interval or p-value for the primary endpoint, so neither precision nor statistical evidence for a change can be assessed from the endpoint entry.

Even when estimates and tests are available, interpretation should consider the endpoint’s clinical meaning, the analysis population, missing observations, and the design. Statistical significance and clinical importance are distinct concepts. The record does not provide a threshold for a clinically important change in LVEF, so no such threshold can be applied to this study’s posted endpoint description.

Planning illustrations are not observed power

The sample-size assumptions describe a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. These assumptions are not a report of the trial’s original design justification. The registry record does not report that justification, and the numerical observed effect and fraction needed to interpret the planning illustration are not reported in the registry record.

In general, a planning calculation estimates how many participants would be needed under its chosen assumptions to detect a specified effect with a chosen level of statistical power. It does not show the probability that the completed study found a true effect, and a retrospective calculation based on an observed effect should not be called observed power. Any sample-size values should be read as planning illustrations, not as evidence about the result. For non-time-to-event outcomes, the stated convention is participants per arm; time-to-event calculations, if present, use total events. The primary endpoint is continuous rather than time-to-event.

Why variation can affect analysis

In general, statistical models may need to reflect the distribution and variability of the outcome. Over-dispersion refers to variation greater than a model assumes; when present, an inappropriate variance assumption can make uncertainty appear smaller than it is. The registry record does not identify a model for the primary endpoint, report a dispersion assessment, or indicate whether over-dispersion was relevant. Because the outcome is described as continuous and summarized by a mean and standard deviation, no specific model or variance correction can be inferred.

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("Control", "Intervention Group")
n   <- c(5, 5)
m   <- c(0.82, -1.9)
sp  <- c(3.54, 1.14)
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  Control  5  0.820  3.540  -3.575  5.215
CARM  Intervention Group  5  -1.900  1.140  -3.315  -0.485

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 5 outcome measures and 5 analyses. It does not report how those outcomes were classified, which analyses were confirmatory, or whether any adjustment was planned for multiple comparisons. When multiple outcomes or analyses are examined, the chance of at least one apparently unusual result can increase if each is assessed separately. In general, multiplicity procedures can control that risk, but no such procedure is described in the registry record. Without the full analysis plan and outcome results, the effect of multiplicity on interpretation cannot be assessed.

Missing-data methods are also not reported in the registry record. The endpoint requires baseline and endpoint measurements, but the record does not state how many participants had measurements at both assessments, whether any measurements were missing, or how missing values were handled. In general, complete-case analysis can be biased when the participants with complete measurements differ systematically from those without them. Other methods rely on assumptions about the missingness process. The record does not identify an approach or its assumptions.

The analysis population is not reported in the registry record. It is therefore unclear whether the reported analyses, if any, included all enrolled participants, only participants who received an intervention, or participants with endpoint measurements. The outcome description’s population field is blank. No participant flow or analysis denominators for the primary endpoint are stated.

These omissions matter because outcome interpretation depends not only on the statistical method but also on who was analyzed and how incomplete information was handled. The completion status and enrollment count do not establish the number contributing to the primary analysis. The registry record does not give enough information to judge whether the endpoint analysis followed a prespecified plan or whether selective reporting could have influenced which results were posted.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: er visit (20.0%), hf exacerbation (20.0%), low bp (20.0%), a-fib hospitalization (20.0%).

The serious adverse-event entries give a descriptive account by group. For Control, 5 participants were at risk and 0 were recorded as affected by serious adverse events. For Intervention Group, 5 were at risk and 4 were recorded as affected. The record lists 0 deaths in each group. Other adverse events are recorded as 0 affected in Control and 1 in Intervention Group, with 5 at risk in each group.

The listed serious-event terms are ER Visit, HF exacerbation, Low BP, and A-fib Hospitalization, each reported as 20.0%. The record does not explain whether these terms represent distinct participants, event episodes, or overlapping categories. It also does not provide event timing, severity grading beyond the serious classification, attribution to an intervention, or a detailed account of follow-up.

These entries should be read as counts recorded in small groups, not as a reliable estimate of comparative risk. Because allocation was non-randomized and the group descriptions are unclear, the safety figures cannot establish that a therapy caused an event or that groups had comparable baseline risk. They are not a substitute for a full adverse-event narrative or a prespecified comparative safety analysis, neither of which is reported in the registry record.

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

The registry record establishes that NCT02275819 was a completed, non-randomized study addressing exercise training and cardiac structure and function in people with heart failure. It identifies change in left ventricular ejection fraction as the primary endpoint and states that measurements were planned at baseline and endpoint at 3-5 months. It also records enrollment of 11 and includes group-level adverse-event entries.

The record does not report numerical results for the primary endpoint. Consequently, it does not show whether LVEF increased, decreased, or remained similar on average, nor how variable or precise any estimate was. A missing numerical result should not be interpreted as a zero change or as a finding of no effect. It means the primary endpoint’s result cannot be evaluated from the registry information recorded.

The study design also constrains causal interpretation. Allocation was non-randomized, the comparator descriptions are incomplete, and the relation between exercise and Inspiratory Muscle Therapy is unclear. Without allocation details, baseline group characteristics, and an analysis plan, group differences could not be attributed confidently to an intervention. The record does not provide information that would resolve those concerns.

In general, an endpoint is only one part of a clinical research question. A change in a cardiac function measure does not, by itself, establish a change in symptoms, functional capacity, or other aspects of cardiac structure. The study description names these broader interests, but the registry record does not supply enough outcome detail to assess them.

The posted information therefore supports a description of the study’s intent, design, and recorded safety counts, but not a conclusion about the size or direction of the primary outcome. It also does not support treatment advice or a judgment about clinical benefit. Numerical endpoint estimates, uncertainty measures, participant flow, and fuller methods would be needed for a more complete statistical interpretation.

14. Why This Trial Matters Statistically

This study illustrates why a registry entry must be read as more than a list of outcomes. The research question concerns cardiac remodeling and function, while the primary endpoint focuses on change in left ventricular ejection fraction. That measure provides a defined, continuous outcome, but the record does not provide its numerical results. An endpoint name alone cannot establish what was observed.

The non-randomized design is also central to statistical interpretation. In general, a comparison between groups is most informative when the groups are sufficiently comparable and the treatment contrast is clearly defined. Here, allocation is listed as non-randomized, and the intervention description refers to exercise and Inspiratory Muscle Therapy without fully clarifying their group structure. These details affect which comparisons are meaningful and what conclusions could follow.

The record further highlights the difference between a study being marked completed and having interpretable results available. Enrollment and completion dates establish administrative aspects of the study, but they do not supply an endpoint estimate, uncertainty interval, or analysis population. Similarly, adverse-event counts are useful descriptive information but do not by themselves resolve comparative safety or causation.

Finally, planning assumptions and analysis methods should not be mistaken for evidence about outcomes. A sample-size illustration based on an observed effect is not observed power and does not replace a reported estimate. For researchers, the statistical lesson is to distinguish the study question, design, analysis, and actual result. The registry record documents the first elements more clearly than the final primary-outcome evidence.

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.

Several limitations specific to this study restrict interpretation. The primary endpoint is named and its timeframe is stated, but its numerical results are not reported in the registry record. No group means, standard deviations, mean change, confidence interval, or test result are available in the endpoint information. This prevents assessment of effect direction, magnitude, and precision.

The study is listed as non-randomized and unmasked. The record does not describe how participants were assigned, whether allocation was influenced by participant or investigator characteristics, or whether baseline groups were comparable. The arm descriptions are also ambiguous: the control is described as receiving no exercise, while the intervention-group description refers to 2 groups receiving exercise or Inspiratory Muscle Therapy. The exact comparison relevant to the primary endpoint is not clear.

Although enrollment is recorded as 11, the registry does not report endpoint-specific denominators, participant flow, or the analysis population. It does not say how missing endpoint data were handled or provide details of the statistical model. The record lists 5 outcome measures and 5 analyses but does not report a multiplicity strategy or explain which outcomes were confirmatory.

The study description emphasizes cardiac structure and function, but the available endpoint entry concerns LVEF. The record does not provide detailed results for the other areas mentioned in the study description. The adverse-event information is also limited: it gives counts and event terms but not timing, attribution, or whether listed terms overlapped. These gaps are especially important when interpreting descriptive counts from a non-randomized study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Exercise Training in Heart Failure: Changes in Cardiac Structure and Function — NCT02275819.
• Registry record last updated 2021-03-08; status last verified 2021-03.
• Results first posted 2021-03-08.
• 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

NCT02275819, titled Exercise Training in Heart Failure: Changes in Cardiac Structure and Function, is listed as completed and sponsored by the VA Office of Research and Development. The record gives enrollment as 11 and describes a non-randomized, unmasked, parallel study. The phase is listed as NA.

The primary endpoint is change in left ventricular systolic function, described as change in left ventricular ejection fraction and measured in percent LVEF. The timeframe is baseline and endpoint at 3-5 months. The record specifies a mean and standard deviation but does not report numerical primary-outcome results.

The intervention descriptions refer to exercise and Inspiratory Muscle Therapy, while the control is described as receiving no exercise intervention. The precise group structure and comparison are unclear. Safety entries list 0 serious adverse events in Control and 4 in Intervention Group, with 5 at risk in each group, and 0 deaths in each group. The record does not report the detailed analysis plan, missing-data methods, or analysis population.