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 Bubble PEP Training Among Patient With Chronic Obstructive Pulmonary Disease in Pulmonary Function Effects (NCT04828837), a randomized na study. The primary outcome is The Chinese Version of Chronic Obstructive Pulmonary Disease Assessment Test(CAT).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04828837 |
| Phase | NA |
| Condition | Chronic Obstructive Pulmonary Disease With Exacerbation, Chronic Obstructive Pulmonary Disease Exacerbation, Chronic Pulmonary Disease |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 57 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Taipei University of Nursing and Health Sciences |
| Results posted | Yes |
2. Clinical Question
Population
People with chronic obstructive pulmonary disease, including conditions recorded as chronic obstructive pulmonary disease with exacerbation, chronic obstructive pulmonary disease exacerbation, and chronic pulmonary disease. The record reports 57 participants randomly assigned overall, while its primary-outcome description lists 13 participants in the experimental group and 14 in the control group; the relationship between these counts is not fully explained.
Intervention
Bubble positive expiratory pressure training, described as bubble PEP training. The intervention is listed as a device.
Comparator
General care, described as routine care on the chest ward.
Primary question
How did the Chinese Version of the Chronic Obstructive Pulmonary Disease Assessment Test (CAT) score change from the pre-test baseline to week 4 in the two groups? The registry record describes assessment at 1 and 4 weeks, with week 4 reported, but does not report the numerical week-4 CAT results or a between-group effect estimate.
3. Trial Design
The registry record describes a randomized, parallel-group trial comparing bubble positive expiratory pressure training with general care. The allocation is listed as randomized, and masking is listed as single; the record does not identify who was masked. The intervention is categorized as a device. The comparator is routine care on the chest ward.
The listed enrollment is 57. The primary-outcome description separately reports 13 participants in the experimental group and 14 in the control group, and says that the groups completed a test. It also reports that, at the one-week assessment, 11 experimental-group participants were analyzed, with a loss of 2, and 6 control-group participants were analyzed, with a cumulative loss of 8. These statements do not fully describe the flow from the overall enrollment to the primary-outcome analysis population.
The primary completion date is 2021-08-31, and the trial status is terminated. The start date is 2021-02-02. The phase is listed as NA. The registry record does not report why the trial was terminated, the allocation procedure, the intended sample-size justification, or the identity of the masked party. It lists re-hospitalization event as a secondary outcome and records four outcome measures and four analyses, but does not provide numerical results for those outcomes in the registry record for this analysis.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: In the study, 30 patients were excluded from the study before assignment to groups4 patients declined to participate, 10 inpatients had used non-invasive PEP treatment before hospitalization, 4 patients has a mental illness, and 12 patients have notifiable respiratory infectious diseases.
Overall Study
| Stage | Bubble Positive Expiratory Pressure Training | General Care |
|---|---|---|
| STARTED | 13 | 14 |
| COMPLETED | 8 | 4 |
| NOT COMPLETED | 5 | 10 |
Reasons for not completing this period:
| Reason | Bubble Positive Expiratory Pressure Training | General Care |
|---|---|---|
| Stay-at-home during a COVID-19 outbreak | 1 | 3 |
| Lost to Follow-up | 2 | 6 |
| Lack of Efficacy | 1 | 0 |
| Admitted due to pneumothorax. | 1 | 0 |
| Admitted due to HIVD for operation. | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: A total of 57 were randomly assigned and complete test, with 13 in the experimental group and 14 in the control group. At T1, the experimental group had 11 analyzed, experiencing a total loss of 2 participants. In comparison, the control group had 6 analyzed at T1, with a cumulative loss of 8 participants. Moving to T2, the experimental group had 8 analyzed, with a total loss of 3 participants. The control group had 4 analyzed at T2, with a cumulative loss of 2 participants.
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.
Population: A total of 27 participants in the study, 13 and 14 were assigned to the intervention and control groups, respectively. Two groups completed the sociodemographic characteristics and baseline test(T0).
| Characteristic | Unit | Bubble Positive Expiratory Pressure Training | General Care | Total |
|---|---|---|---|---|
| Participants analysed | 13 | 14 | 27 | |
| Age, Customized: Age : < 70 | Participants | 6 | 4 | 10 |
| Age, Customized: Age : >= 70 | Participants | 7 | 10 | 17 |
| Sex: Female, Male: Female | Participants | 1 | 1 | 2 |
| Sex: Female, Male: Male | Participants | 12 | 13 | 25 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 13 | 14 | 27 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: Taiwan | participants | 13 | 14 | 27 |
| Marital status: divorced/Single | Participants | 5 | 4 | 9 |
| Marital status: married | Participants | 8 | 10 | 18 |
| Occupation: blue-collar worker | Participants | 7 | 10 | 17 |
| Occupation: white-collar worker | Participants | 6 | 4 | 10 |
| Smoking history: smoking | Participants | 3 | 4 | 7 |
| Smoking history: non-smoking | Participants | 1 | 1 | 2 |
| Smoking history: quit-smoking | Participants | 9 | 9 | 18 |
| Chronic comorbidities: Hypertension | Participants | 6 | 7 | 13 |
| Chronic comorbidities: Diabetes mellitus | Participants | 1 | 2 | 3 |
| Chronic comorbidities: Heart disease | Participants | 6 | 6 | 12 |
| Chronic comorbidities: Pneumothorax | Participants | 0 | 2 | 2 |
| Chronic comorbidities: Lung cancer | Participants | 1 | 0 | 1 |
| COPD Grade: GOLD 2(FEV1 50-79) | Participants | 2 | 6 | 8 |
| COPD Grade: GOLD 3(FEV1 30-49) | Participants | 11 | 8 | 19 |
| Dry powder bronchodilator use (day) | days | 7.25 (SD 4.31) | 3.30 (SD 2.41) | 5.45 (SD 4.0) |
6. Primary Endpoint
The registry lists the primary outcome as The Chinese Version of Chronic Obstructive Pulmonary Disease Assessment Test(CAT), measured over The pre-tests within 48 hours of hospitalization, which served as the baseline of the intervention (T0). Assessed at 1(T1) and 4(T2) weeks, week 4 was reported..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the Chinese Version of the Chronic Obstructive Pulmonary Disease Assessment Test (CAT), recorded as a mean score with standard deviation. The registry record describes eight items assessing the degree of dyspnea. Each item ranges from 0 to 5 points; the total score ranges from 0 to 40. A higher score indicates a higher degree of dyspnea, according to the endpoint description.
The CAT is used in this trial as a patient-reported measure of respiratory symptom burden. Repeated measurement can describe how scores change over time, while comparing groups can help estimate whether their observed changes differ. That interpretation depends on the actual group scores, their variability, and the analysis method. The record describes a pre-test within 48 hours of hospitalization as baseline (T0), with further assessment at 1 week (T1) and 4 weeks (T2); it says week 4 was reported. Numerical baseline or week-4 CAT results, a change estimate, and a measure of uncertainty are not reported in the registry record. The endpoint definition alone therefore establishes what was measured, but not the direction or size of any group difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a randomized comparison and defines a continuous primary endpoint, but the numerical CAT results needed to interpret the treatment contrast are not reported in the registry record. In particular, there are no posted group means, standard deviations, between-group estimate, confidence interval, or p-value in the registry record for this analysis. Without those results, the magnitude, direction, and precision of the primary-outcome comparison cannot be described.
The endpoint is oriented so that higher CAT scores indicate a higher degree of dyspnea. That direction helps interpret a reported score, but it does not establish what happened in either group. No statement about improvement, worsening, similarity, or statistical significance follows from the endpoint definition or from the trial’s randomized design alone.
Participant counts require careful qualification. The registry record reports 57 participants randomly assigned overall, but its primary-outcome description lists 13 experimental and 14 control participants. It gives one-week analyzed counts of 11 and 6, respectively, and reports losses of 2 and a cumulative 8. The record says week 4 was reported, but does not give the week-4 analysis counts or explain the participant flow from the overall enrollment to the group counts. The available account therefore does not establish how many participants contributed to the primary comparison at the reported time point.
General statistical interpretation: a confidence interval expresses the uncertainty around an estimated effect under the analysis assumptions. A narrower interval indicates greater precision than a wider interval, while an interval that includes values representing no group difference may leave the direction or size of the effect uncertain. No interval is reported for this CAT comparison, so its precision cannot be assessed.
The trial is listed as terminated, but the reason is not reported in the registry record. Termination status alone does not explain why the study ended or how it affected the availability of results. The record also lists re-hospitalization event as a secondary outcome, without numerical findings in the registry entries. The defensible reading is therefore limited: the record describes the design, endpoint, and some participant counts, but does not report the primary numerical results required to characterize the observed treatment contrast.
9. Statistical Methods Explained
The registry record identifies the primary endpoint as a continuous measure summarized by a mean and standard deviation. It describes a randomized, parallel-group comparison of bubble positive expiratory pressure training with general care. However, numerical CAT outcome results and the statistical model or test used for the primary comparison are not reported in the registry record.
What does a mean and standard deviation describe?
General statistical explanation: a mean describes the central value of a set of measurements. A standard deviation describes how dispersed individual measurements are around that mean. For a continuous endpoint such as a score, these summaries provide information about both the typical observed score and variation among participants. They do not, on their own, quantify the uncertainty in a comparison between groups. That usually requires an effect estimate and an uncertainty measure, such as a confidence interval, or a test result. Those numerical comparison results are not reported for the CAT endpoint in the registry record.
What does randomization contribute?
General statistical explanation: random allocation is intended to make assigned groups comparable, on average, with respect to factors present before treatment assignment. It can support a causal interpretation when the trial is conducted and analyzed appropriately, but randomization does not guarantee identical groups in a particular trial. Nor does the design itself show the size or precision of an outcome difference. The record lists randomized allocation, but does not report the allocation sequence or concealment procedures.
The design is described as parallel, meaning that the record presents separate groups receiving the intervention and comparator. Masking is listed as single, but who was masked is not reported in the registry record. That missing detail matters when considering possible influences on outcome measurement, participant reporting, or other aspects of study conduct; it cannot be resolved by assuming a particular masking arrangement.
How should repeated assessments be understood?
The endpoint description gives a baseline pre-test within 48 hours of hospitalization (T0), followed by assessments at 1 week (T1) and 4 weeks (T2). It says week 4 was reported. General statistical explanation: repeated measurements can be analyzed by comparing groups at a specified time point, comparing changes from baseline, or using a model that accounts for measurements from the same participant over time. These approaches answer related but not identical questions and can yield different estimates. The registry record does not report which approach was used, how baseline values entered the analysis, or whether results at the other assessment time points were analyzed or reported.
Why do missing observations matter?
The primary-outcome description reports that 11 experimental-group participants and 6 control-group participants were analyzed at T1, with losses of 2 and a cumulative loss of 8, respectively. General statistical explanation: when outcome data are missing, the analyzed participants may differ from those without measurements. If missingness is related to participant characteristics or outcomes, a comparison limited to observed measurements can be difficult to interpret. The record does not describe reasons for missing observations, a method for handling missing data, or a sensitivity analysis. It also does not provide the week-4 analysis counts, despite stating that week 4 was reported.
What can be said about statistical significance and precision?
General statistical explanation: a p-value is one way to assess how compatible observed data are with a specified null hypothesis under a statistical model. A confidence interval gives a range of effect estimates compatible with the data and model, and is especially useful for understanding precision and the plausible scale of a difference. Neither statistic alone determines clinical importance. The CAT comparison has no reported p-value, confidence interval, or numerical effect estimate in the registry record, so statistical significance and precision cannot be assessed from the available results.
Sample-size planning and observed results are also distinct. A planning illustration is not an observed trial finding, and planned power is not evidence that a trial detected an effect. No numerical planning estimates are included in the registry record for this analysis, and the registry record’s sample-size justification is not reported. No particular statistical model, adjustment set, interim analysis, or analysis population should be inferred from the design description alone.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists four outcome measures and four analyses, with re-hospitalization event named as a secondary outcome. The complete set of outcomes, analysis details, and numerical results is not reported in the registry record for this analysis. The primary outcome description identifies CAT, but does not provide the numerical results for its reported week-4 assessment.
Multiplicity arises when several outcomes, time points, or statistical comparisons are examined. General statistical explanation: considering many tests can increase the chance of at least one apparently notable result, so interpretation depends on which outcomes and comparisons were planned and whether any adjustment or prioritization was used. The registry record does not report a multiplicity strategy, a prespecified hierarchy, or which analyses were primary versus exploratory beyond identifying CAT as the primary endpoint and re-hospitalization event as secondary.
Missing-data reporting is also incomplete. At T1, the experimental group had 11 participants analyzed and a loss of 2; the control group had 6 analyzed and a cumulative loss of 8. The reasons for these losses, the approach to missing observations, and any sensitivity analyses are not reported in the registry record. Although the endpoint description says week 4 was reported, the corresponding analysis counts are not stated. The overall enrollment of 57 and the primary-outcome description’s group counts of 13 and 14 are not reconciled.
The analysis population is not defined beyond the participant counts described. It is not reported whether the primary analysis included everyone as randomized, only participants with observed outcomes, or another population. These omissions limit assessment of potential attrition bias and of how closely the reported analysis, if available, would reflect the randomized comparison.
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 |
|---|---|---|---|
| Bubble Positive Expiratory Pressure Training | 0 | 13 | 0.0% |
| General Care | 0 | 14 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Bubble Positive Expiratory Pressure Training | 0 of 13 |
| General Care | 0 of 14 |
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 |
|---|---|
| Bubble Positive Expiratory Pressure Training | 0 of 13 |
| General Care | 0 of 14 |
The registry record lists serious adverse event counts of 0 among 13 participants at risk in the bubble positive expiratory pressure training group and 0 among 14 participants at risk in the general care group. It also lists other adverse event counts of 0 among 13 and 0 among 14, respectively. Deaths are listed as 0 in both groups. No serious adverse event terms are listed.
These figures describe the posted counts for the groups and at-risk numbers specified in the record. They do not, by themselves, establish that no events occurred outside the recorded categories, nor do they provide an event rate over a defined follow-up period. The adverse-event follow-up timeframe and the method of collection are not reported in the registry record. The listed at-risk counts also differ from the overall randomized enrollment, and the registry record does not explain the relationship between these safety populations and all randomized participants.
General statistical explanation: when event counts are small or zero, the observed count alone gives limited information about how uncertain the underlying risk may be. A comparison of safety between groups would require appropriate context, including follow-up duration and participant exposure, neither of which is reported in the available record. These figures should therefore be read as the event counts recorded, not as proof that risk was absent or that the groups had equivalent safety.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, parallel-group trial compared bubble positive expiratory pressure training with routine chest-ward care, and that the primary endpoint was the Chinese Version of the CAT. It also describes the score’s range and direction: the total ranges from 0 to 40, with higher scores indicating a higher degree of dyspnea. The record reports assessment at baseline and at 1 and 4 weeks, with week 4 identified as reported.
What the posted information does not establish is the CAT result. Numerical group scores, a between-group estimate, and measures of uncertainty are not reported in the registry record. As a result, the observed direction, size, and precision of the primary comparison cannot be stated. The endpoint description and the randomized design are not substitutes for outcome data.
The record reports 57 randomized participants, while the primary-outcome description gives group counts of 13 and 14 and provides one-week analyzed counts of 11 and 6. The participant flow, reasons for losses, and week-4 analyzed population are not fully described. These gaps make it difficult to judge how complete the outcome data were or which participants contributed to the reported time point.
The safety figures list no serious or other adverse events and no deaths in the specified at-risk groups. They are counts, not a complete estimate of risk over a stated follow-up period, because the relevant duration and collection details are not reported in the registry record.
The trial’s terminated status is recorded, but the reason is not reported. Taken together, the information characterizes the planned comparison, endpoint, some participant counts, and posted safety counts. It does not support a conclusion about whether the intervention changed CAT scores, how large any difference was, or how certain such a difference might be.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of why a design description and a result are different kinds of evidence. Randomized allocation identifies the intended comparison, and the CAT definition clarifies what was measured. But without numerical endpoint results and an effect estimate, the central statistical question—how the groups compared at the reported time point—remains unanswered by the registry record.
The participant counts also illustrate why analysis populations and follow-up completeness matter. The record reports overall enrollment of 57, group counts of 13 and 14 in the primary-outcome description, and different analyzed counts and losses at T1. The way these numbers relate is not fully described. Reporting the participant flow and the number contributing to each time point is necessary to understand the evidence behind an estimate and the potential influence of missing observations.
The primary endpoint is a repeated continuous measure, with baseline and follow-up assessments described. General statistical explanation: choices about comparing follow-up scores, changes from baseline, or trajectories over time can affect the question answered by an analysis. Clear reporting of the chosen analysis, its assumptions, and uncertainty would help readers interpret the result. Those analysis details are not reported in the registry record.
The trial is listed as terminated, but no reason is reported. The record also provides safety counts without a stated adverse-event follow-up period. Together, these details show why statistical interpretation depends not only on design labels, but also on complete outcome reporting, transparent missing-data handling, and a clearly defined analysis population. The registry entries permit a precise description of what was planned and which counts were recorded, while leaving the primary comparative result unreported.
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 is that numerical results for the primary CAT endpoint are not reported in the registry record. There are no group means or standard deviations, no between-group estimate, and no reported confidence interval or p-value. Therefore, neither the magnitude nor the precision of the primary comparison can be evaluated.
Participant accounting is incomplete. The record states that 57 participants were randomly assigned, but the primary-outcome description lists 13 experimental-group participants and 14 control-group participants. At T1 it reports 11 and 6 analyzed, with a loss of 2 and a cumulative loss of 8. The relation between these counts, the reasons for loss, and the number analyzed at week 4 are not reported. The record’s statement that week 4 was reported does not resolve those gaps.
The statistical analysis plan is not described in the registry record for this analysis. The method for comparing groups, use of baseline measurements, handling of missing data, analysis population, and any sensitivity analyses are not reported in the registry record. The record lists four outcome measures and four analyses, but does not specify a multiplicity approach. The identity of the masked party is also not reported.
The registry status is terminated, but the reason is not reported. Safety counts are listed for groups of 13 and 14, without a reported adverse-event follow-up timeframe or collection method. These limits apply to interpretation of both the primary endpoint and the safety information. They do not establish what unreported analyses or events may have occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Bubble PEP Training Among Patient With Chronic Obstructive Pulmonary Disease in Pulmonary Function Effects — NCT04828837.
- Registry record last updated 2024-12-11; status last verified 2024-10.
- Results first posted 2024-12-11.
- 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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18. Record Summary
NCT04828837 is listed as a randomized, single-masked, parallel-group trial of bubble positive expiratory pressure training versus general care for people with chronic obstructive pulmonary disease. Enrollment is listed as 57, and the status is terminated. The primary completion date is 2021-08-31.
The primary endpoint is the Chinese Version of the CAT, described as a mean score with standard deviation. The assessment schedule includes baseline within 48 hours of hospitalization, 1 week, and 4 weeks; the record says week 4 was reported. The scale ranges from 0 to 40, with higher scores indicating a higher degree of dyspnea.
Numerical CAT results and the primary comparison estimate are not reported in the registry record. The record lists re-hospitalization event as a secondary outcome and records zero serious adverse events, zero other adverse events, and zero deaths in the specified groups. Reasons for termination, missing-data methods, the analysis population, and the week-4 analyzed counts are not reported.