Does Pulmonary Rehabilitation Improve Frailty?: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Does Pulmonary Rehabilitation Improve Frailty? (NCT02512874), a na na study. The primary outcome is Number of Participants With Frailty Phenotype at Baseline and 6 Months.

2. Clinical Question

The clinical question is whether frailty measures changed after pulmonary rehabilitation among participants with chronic lung disease. The registry’s background describes frailty as involving weakness, slowness, low physical activity, exhaustion, and wasting, and notes its association with hospitalization and death in lung disease. Those statements motivate the study; they are not results of this trial. With no control arm and no posted primary outcome values, the record does not establish whether frailty changed, how large any change was, or whether any change was attributable to rehabilitation.

3. Trial Design

The registry describes a completed, single-group study sponsored by Mayo Clinic. Its title asks whether pulmonary rehabilitation improves frailty in chronic lung disease. The study began on 2015-07-21, had a primary completion date of 2018-10-16, and is listed as completed. Enrollment is reported as 65. The phase and allocation are recorded as NA, and masking is recorded as NONE.

All participants were assigned to the pulmonary-rehabilitation arm as described in the record; no separate control arm is listed. Participants were to receive questionnaires, DEXA scans, dynamometer and gait-speed tests, and activity measurement with a monitor. The primary outcome concerns frailty phenotype at baseline and six months. The listed secondary outcomes concern wasting, strength, gait speed, exhaustion, and physical activity.

This design can describe measurements made before and after rehabilitation in the study group, but it does not make a randomized or concurrent between-group comparison. A before-and-after pattern, if reported, would not by itself distinguish an intervention effect from other explanations, such as changes over time, co-occurring care, or differences in who completed follow-up. These are general interpretive considerations, not claims that any particular alternative explanation occurred in this study.

The registry record does not report the detailed intervention schedule, adherence, eligibility criteria, or the statistical plan. It also does not report how participants were selected for follow-up assessment or provide a detailed account of participant flow. The designation of the study as completed indicates its registry status, not that all planned outcome results are available in the record.

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

Analysis population for the primary outcome, as defined in the registry: Forty-nine participants (77.8%) of the 63 participants completed at lease one follow-up frailty parameter assessment after completion of pulmonary rehabilitation.

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 Number of Participants With Frailty Phenotype at Baseline and 6 Months, measured over Baseline, Six months.

The primary endpoint is the number of participants with the frailty phenotype at baseline and six months. The record defines the phenotype as three or more of the following features: slow gait speed, exhaustion, decreased hand-grip strength, decreased activity level, or wasting. Grip strength, gait speed, and exhaustion are described with reference to Fried et al. 2001. Wasting is defined as further decrease in fat-free mass measured by DEXA, and low physical activity as activity-monitor measurement in the lower quartile.

In general, a composite phenotype combines several related features into one classification. Such an endpoint can represent more than one aspect of health, but the combined classification does not show which individual feature is responsible for a participant’s status. The separate measures matter when interpreting whether a change is broad or concentrated in one component.

The registry states that the primary measure is assessed at baseline and six months, but does not report the number meeting the definition at either time point, the number who changed classification, or an estimate comparing the assessments. It therefore describes how the endpoint is defined without supplying the outcome values needed to quantify change. The record’s follow-up statement refers to at least one frailty-parameter assessment, which does not establish that every component of the composite was observed for every participant.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record defines a binary-type primary outcome through a threshold on a set of frailty features. A participant is classified as having the phenotype if at least three of the listed features are present. The posted primary measure is a count of participants meeting that definition at baseline and six months. The record does not provide the counts themselves or explain the statistical procedure used to compare assessments.

What does a count endpoint show?

In general, a count of participants meeting a criterion gives the frequency of that classification in the assessed group. It is different from a continuous measure such as gait speed or grip strength, which retains the measured value rather than reducing it to a category. Threshold-based classification can be useful for describing a syndrome, but it can obscure how close individual measurements are to a threshold and which components determine classification.

For a repeated assessment, a comparison of group-level counts at two time points does not by itself show how individual participants changed. In general, participant-level transitions can distinguish people who newly meet the definition from those who no longer meet it, while separate cross-sectional counts cannot identify those transitions. The registry record does not report transition counts or state whether the analysis used participant-level paired information.

Why does the single-group design matter?

In general, measuring the same group before and after an intervention can describe temporal change. But without a concurrent comparator, it cannot establish what would have happened to the group over the same period in the absence of the intervention. Changes may reflect the intervention, the course of illness, other care, measurement variability, or changes in who remains available for assessment. These are general limitations of uncontrolled before-and-after comparisons; the record does not establish that any specific explanation accounts for this study’s unreported outcome.

The record lists allocation as NA and describes a single group, so it does not report random assignment between intervention and control. Masking is recorded as NONE. In general, masking can reduce some forms of influence on assessment or reporting, depending on the outcome and who is masked. The record does not describe further masking procedures or how assessors conducted measurements.

What does uncertainty estimation add?

In general, an estimate describes the size and direction of an observed association or change, while a confidence interval expresses its statistical uncertainty under specified assumptions. A p-value, when used, assesses compatibility between the data and a stated null hypothesis under a statistical model; it is not a measure of clinical importance and does not convey the size of an effect. Neither a confidence interval nor a p-value for the primary endpoint is reported in this registry record. Without an estimate and its uncertainty, readers cannot assess the precision of a treatment-associated change from this entry.

The record’s assumptions for a sample-size planning illustration refer to a hypothetical two-arm calculation, equal allocation, a two-sided significance level of 0.05, and a normal approximation. Those are described as planning assumptions based on an observed effect, not as the study’s own design. No planning values are given in the registry record for interpretation here, and such illustrations would not represent observed power or replace the trial’s own analysis. The registry does not report a sample-size justification for this single-group study.

How should the component measures be understood?

The primary definition combines gait speed, exhaustion, hand-grip strength, activity, and wasting. In general, these components may have different measurement properties and may not move together. The record identifies DEXA for body-composition measurement, a dynamometer for grip strength, a gait-speed test, questionnaires, and an activity monitor. It does not provide the instruments’ detailed protocols, scoring procedures, thresholds beyond the phenotype description, or the numerical component results.

The registry lists one analysis, but does not report the model, estimand, covariate adjustment, handling of repeated measurements, or inferential procedure. These details are needed to understand exactly what quantity was estimated and which assumptions supported it. No method should be inferred from the outcome’s binary classification alone. The endpoint definition describes how participants are categorized; it does not specify how the statistical analysis was performed.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and secondary outcomes concerning wasting, strength, gait speed, exhaustion, and physical activity. It does not report a multiplicity strategy, such as a hierarchy of testing or adjustment across outcomes. In general, examining several outcomes can increase the chance that at least one appears notable by chance, so prespecification and transparent interpretation are important. The record does not provide enough detail to assess how this issue was addressed.

Missing-data information is limited. The registry reports that 49 participants (77.8%) of the 63 participants completed at least one follow-up frailty-parameter assessment after rehabilitation. That wording does not establish complete six-month assessment for the primary phenotype, nor does it say how many measurements were available for each component. The record does not explain why assessments were missing, how missing values were handled, or whether any sensitivity analyses were conducted.

The enrollment figure is 65, whereas the follow-up statement refers to 63 participants. The record does not reconcile these figures, describe the status of every participant, or specify the population used for the primary analysis. It is therefore not possible to determine from the registry whether the analysis included everyone enrolled, only participants with available follow-up, or another population.

In general, missing-data methods depend on the amount and pattern of missingness and on assumptions about why values are unavailable. Analyses restricted to observed assessments can be affected if people with and without follow-up differ. That is a general consideration, not evidence of a particular bias in this trial. The registry record does not report enough information to evaluate the assumptions behind any analysis or to judge the influence of incomplete outcome data.

11. 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.

The registry reports safety figures for the pulmonary-rehabilitation group. For serious adverse events, 0 were reported among 65 participants at risk. For other adverse events, 0 were reported among 65 participants at risk. The record separately reports 4 deaths. It does not identify the causes of death, their timing, or whether they were considered related to rehabilitation.

These are registry counts, not a comparative safety estimate. Because the study has no control arm, the figures cannot show whether events were more or less frequent than they would have been without rehabilitation. The record also does not provide event descriptions, definitions, duration of safety observation, or a narrative explaining how deaths were classified. No serious adverse-event terms are listed.

In general, a report of zero recorded events means none were entered in that category for the stated group and risk denominator; it does not establish that no unrecorded events occurred or that risk is absent. Deaths should not be assumed to be adverse events related to the intervention when the registry does not state that relationship. The figures describe what the record reports, not a causal safety conclusion.

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

The record describes a study of pulmonary rehabilitation and frailty in chronic lung disease, with one group assessed at baseline and six months. It defines the primary phenotype and identifies the planned measurements. It also reports that 49 participants (77.8%) of the 63 participants completed at least one follow-up frailty-parameter assessment. These details help readers understand the question and the available follow-up information.

The record does not report the primary endpoint counts, the amount or direction of change, or an uncertainty estimate. Accordingly, the result cannot be characterized as an improvement, worsening, or lack of change based on this registry entry. The title and study rationale express the question being investigated; they are not evidence of an outcome.

Even if outcome values were available, the single-group structure would limit causal conclusions. A within-group difference over time would not show how participants would have changed without rehabilitation. In general, a concurrent comparison helps address that counterfactual question, while an uncontrolled observation cannot separate the intervention from other influences. No conclusion about effectiveness follows from the design description alone.

The listed secondary outcomes indicate that the study considered several dimensions of frailty, but their numerical results are not reported. The record also does not specify the primary analysis method, the treatment of missing measurements, or a multiplicity approach. Those omissions limit the ability to assess the statistical evidence even apart from the missing primary outcome values.

The safety entries report no serious or other adverse events in the recorded categories among the stated at-risk group, and separately list deaths. The record does not provide causes or attribution, so those figures should be read as descriptive reporting rather than evidence that rehabilitation caused or prevented any event. Overall, the registry entry documents a study question and measurement framework, but does not contain enough outcome information to determine what the trial found about frailty.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of the difference between a clear endpoint definition and a reported result. The registry describes how frailty phenotype is determined and when it is assessed, but does not supply the counts or estimate needed to quantify change. Knowing the measurement rule is necessary for interpretation; it is not a substitute for the observed outcome.

The record also illustrates why follow-up coverage and outcome completeness are not interchangeable. It reports that participants completed at least one follow-up frailty-parameter assessment, but this does not establish that every component was measured for every participant at the relevant time point. A transparent account of available observations and missing assessments is essential for understanding who contributes to an analysis and how representative the analyzed group may be.

The single-group design makes the distinction between change and treatment effect especially important. In general, before-and-after measurements can describe what happened within a group, but a comparator is needed to estimate how that pattern differs from an alternative course. This distinction applies even when measurements are objective or the intervention is clinically plausible.

Finally, the record lists a composite primary outcome and several related secondary measures. In general, reporting both the combined endpoint and its components can help readers understand what drives any overall pattern, while a stated analysis plan clarifies how multiple outcomes and incomplete data were handled. Those results and details are not reported in this registry record. The trial therefore matters statistically as a case where the question and measurement framework are documented more fully than the findings needed to judge the evidence.

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 central limitation for interpretation is that the registry record does not report the primary outcome counts at baseline or six months, the estimated change, or uncertainty around that estimate. It also does not report numerical results for the listed secondary outcomes. The study’s central question therefore cannot be answered from the outcome information in this record.

The single-group design has no concurrent control arm, so any observed temporal pattern would not by itself identify an effect attributable to rehabilitation. Masking is recorded as NONE. The registry does not describe assessor procedures or provide details that would allow readers to evaluate how measurement or reporting may have been influenced.

Follow-up information is incomplete for evaluating the primary endpoint. The record reports at least one follow-up parameter assessment for 49 participants (77.8%) of the 63 participants, but does not provide component-specific completeness, reasons for unavailable data, or the analysis population. It also does not explain the relation between that denominator and the enrollment of 65. The possibility of bias from missing observations cannot be assessed using the reported information.

The registry does not report the statistical model, the treatment of repeated measurements, adjustment for covariates, multiplicity procedures, or sensitivity analyses. It also does not provide detailed eligibility criteria, participant characteristics, intervention adherence, or the measurement protocols. These omissions limit assessment of the analysis assumptions, generalizability, and the degree to which the planned intervention was received as intended.

The safety record gives event counts but does not report event descriptions, timing, causes of death, or attribution. Thus it does not support a comparative or causal assessment of safety. These limitations concern what can be concluded from the registry record; they do not establish that the study itself did not collect additional information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Does Pulmonary Rehabilitation Improve Frailty? — NCT02512874.
• Registry record last updated 2020-06-23; status last verified 2020-06.
• Results first posted 2018-10-05.
• 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.

18. Record Summary

NCT02512874 is a completed, single-group study sponsored by Mayo Clinic, with enrollment of 65. It examined pulmonary rehabilitation and frailty in chronic lung disease, with a primary outcome defined as the number of participants meeting the frailty phenotype at baseline and six months. The registry lists questionnaires, DEXA, dynamometer and gait-speed testing, and activity monitoring.

The record reports that 49 participants (77.8%) of the 63 participants completed at least one follow-up frailty-parameter assessment after rehabilitation. It does not report the primary outcome counts, a change estimate, or numerical secondary results. It lists 0 serious adverse events and 0 other adverse events among 65 participants at risk, and separately reports 4 deaths, without causes or attribution. The single-group design and limited outcome reporting prevent a controlled estimate of rehabilitation’s effect on frailty.