MetaNeb® Chest X-ray Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for MetaNeb® Chest X-ray Study (NCT02871258), a na na study. The primary outcome is Chest X-ray Score at Day 2 (Approximately 48 Hours) After Initiation of Therapy With The MetaNeb® System..

2. Clinical Question

The clinical question is whether chest X-ray assessments of atelectasis change after initiation of MetaNeb® System therapy in this enrolled group. The assessment is based on a radiographic scoring scale rather than a direct comparison of treatment groups. A blinded reader scored each lung separately, and the left- and right-lung scores were averaged for each subject. The record does not report the resulting subject-level averages or a group summary.

Other listed outcomes include Kelly scores at later assessment times, a comparative chest X-ray scale, oxygenation, reported dyspnea, and physician assessment of respiratory status. Results for these outcomes are not reported in the registry record. Because there is no control group, any observed change over time would describe the course of the enrolled group during treatment; it would not by itself separate treatment effects from other changes over time.

3. Trial Design

NCT02871258, titled “MetaNeb® Chest X-ray Study,” is recorded as completed. The study began in 2016-09, and primary completion is listed as 2017-08-17. Hill-Rom is the sponsor. The registry lists the phase as NA, allocation as NA, masking as none, and the model as single group. Enrollment was 8.

The registry summary describes a non-randomized, open-label study in which all subjects received the MetaNeb® System. The treatment description specifies use for a minimum of 48 hours, or until hospital discharge if discharge occurred within 48 hours of initial treatment. The summary says treatment would follow the device’s labeled instructions and that duration and frequency would be defined in treatment procedures. Those procedures and further details of actual treatment delivery are not reported in the registry record.

The main radiographic assessment was scheduled at approximately 48 hours after treatment initiation. The primary outcome description says a blinded reader scored each lung separately with the Kelly scoring system, then the two lung scores were averaged for each subject. This reader blinding is a feature of the outcome assessment; it does not change the registry’s description of the overall study as open-label.

The outcome list also includes chest X-ray assessments at approximately 24 hours and approximately 96 hours or discharge, a comparative radiographic scale, oxygenation index, patient-reported dyspnea, and physician-assessed respiratory status. The registry lists 6 outcome measures. It does not report results or analysis details for these outcomes. A formal sample-size justification, the rationale for the enrollment target, and further protocol details are not reported in the registry 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

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 Chest X-ray Score at Day 2 (Approximately 48 Hours) After Initiation of Therapy With The MetaNeb® System., measured over Approximately 48 hours post-initiation of therapy with The MetaNeb® System..

The primary endpoint is the chest X-ray score at Day 2, approximately 48 hours after initiation of therapy with the MetaNeb® System. The Kelly scoring system is used to assess the presence of atelectasis. Its scale runs from 0, representing normal clear lungs, to 4, representing consolidation of the whole lung. Intermediate score descriptions include linear atelectasis, involvement of portions of a hemidiaphragm, lobar consolidation, lobar collapse, and bronchial consolidation.

A blinded reader scored the left and right lungs separately. Those two scores were averaged to form a mean score for each subject. The endpoint description says Day 2 scores were compared with baseline scores. However, the registry record does not report the baseline or Day 2 values, a group mean, a change from baseline, or a measure of uncertainty for the endpoint.

In general, a radiographic score converts an image assessment into a structured measure that can be summarized across subjects and assessment times. Its interpretation depends on the scoring definitions and how consistently images are read. The registry record describes the scale and the averaging procedure, but does not report reader agreement, validation details, or the results needed to assess the observed change. Therefore, the endpoint can be described, but its result and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is described as a mean of a continuous measure, with standard deviation as the stated dispersion measure. The underlying Kelly score uses ordered categories to represent different radiographic findings, including fractional score levels. The registry describes averaging the left- and right-lung scores for each subject. It does not report a group mean or standard deviation for the primary outcome.

What does a mean describe?

In general, a mean is a measure of the center of a set of values. For a group summary, it combines the subject-level measurements into one average. Here, the described subject-level measurement is the average of the scores from the two lungs. A group mean could summarize those subject-level values at Day 2, or summarize change from baseline if the analysis were defined that way. The registry record does not report either summary, so no numerical interpretation of the endpoint is possible.

What does a standard deviation describe?

In general, a standard deviation describes how spread out individual measurements are around their mean. A small standard deviation indicates that values tend to be closer to the mean; a larger one indicates more variation among measurements. It is not the same as a confidence interval, and it does not by itself show how precisely the mean has been estimated. Although standard deviation is named as the dispersion measure, no value is reported for the primary outcome.

How should a confidence interval be understood?

In general, a confidence interval gives an estimate together with a range reflecting statistical uncertainty under a specified method and assumptions. Its width depends on factors such as variability and the amount of information available. It can help distinguish a relatively precise estimate from one that is uncertain. The registry record does not report a confidence interval or enough outcome summaries to assess precision for the primary endpoint. No new interval can be derived from the information reported.

What does the radiographic scoring procedure contribute?

The Kelly system gives the reader a defined scale for assessing atelectasis on chest X-rays. The record describes a score of 0 as normal clear lungs and a score of 4 as whole-lung consolidation, with intermediate descriptions for other findings. Each lung is scored independently, and the two scores are averaged for each subject. In general, a consistent scoring procedure can make image assessments easier to summarize, but the reliability of a score also depends on how consistently readers apply it. Reader agreement and repeatability are not reported in the registry record.

The record says that a blinded reader scored the images. In general, blinding an outcome assessor can help limit influence from expectations about treatment or study timing. The record does not explain how images were presented to the reader, whether the reader remained unaware of assessment timing, or how blinding was evaluated. The study itself is described as open-label, so the reader’s blinding should not be taken to mean that participants or other study personnel were blinded.

What can a baseline comparison show?

In general, comparing a participant’s measurement at follow-up with that participant’s baseline measurement can describe how the measured outcome changed over time. It does not create a control group. If changes in other care, the natural course of illness, or measurement conditions occur during the same period, a single-group comparison cannot isolate their contributions. The registry says Day 2 scores were compared with baseline scores but does not report the comparison method or its results.

Three of the 8 subjects did not have measurable atelectasis at baseline and were excluded from Kelly Score analyses. The registry record does not state how the analysis set was otherwise defined, whether any post-baseline assessments were unavailable, or how missing observations were handled. It also does not report whether the primary analysis used individual Day 2 scores, changes from baseline, or another summary beyond the endpoint description’s statement that Day 2 scores were compared with baseline.

A planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Such an illustration is hypothetical and does not describe the actual single-group study design. The record does not report the numerical planning results or the observed effect needed to interpret them. Planning calculations are not observed power and do not establish what the study found.

The registry lists 0 analyses. No statistical test, model, adjustment method, or inferential procedure for the primary endpoint is reported in the registry record. It would therefore be inappropriate to infer that a particular test was used from the endpoint’s mean-and-standard-deviation description alone. Statistical methods should be interpreted from the analysis actually reported, not assumed from the type of outcome.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures, including the primary chest X-ray score and several secondary assessments. These include Kelly scores at additional assessment times, a comparative chest X-ray scale, oxygenation index, patient-reported dyspnea, and physician-assessed respiratory status. Results for these outcomes are not reported in the registry record.

When a study evaluates multiple outcomes or assessment times, the number of statistical questions can affect how often a seemingly notable result arises by chance. In general, multiplicity refers to this issue and to methods for defining or adjusting the interpretation of multiple tests. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or a designation of which secondary analyses were confirmatory. No adjustment method should be assumed.

The record lists 0 analyses. It does not report a statistical analysis plan, prespecified analysis populations, or whether analyses followed the intention-to-treat principle or another approach. The primary outcome description says 3 of the 8 subjects lacked measurable baseline atelectasis and were excluded from Kelly Score analyses, but the record does not specify the final analysis population or the number with usable Day 2 images.

Missing-data definitions, reasons for missing measurements, and methods for handling missing outcomes are not reported in the registry record. There is also no description of sensitivity analyses or how participants discharged before scheduled follow-up were handled for the primary outcome. The registry mentions discharge timing for treatment duration and for certain secondary assessment times, but does not specify the analysis treatment of missing or early-discharge observations. Without these details and the outcome data, the robustness of any endpoint estimate cannot be assessed.

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 adverse-event record lists 8 subjects at risk for serious adverse events and 0 affected. It also lists 8 subjects at risk for other adverse events and 0 affected. The deaths count is 0. These are the posted counts for this study; the registry record does not list serious adverse-event terms.

In general, a count of zero means that no events of that category were recorded among the listed subjects at risk in the registry entry. It does not establish that the risk is absent, and it does not show how safety would compare with a different treatment or no treatment. With enrollment of 8, the observed counts describe only this small enrolled group. The record does not report additional information about event collection, follow-up completeness, severity definitions, or attribution.

The safety figures should also be read separately from the radiographic outcome. They do not provide information about the size or precision of any change in Kelly score, and no efficacy result is reported in the registry record. The absence of listed events in these categories is a description of the posted counts, not a comparative safety estimate.

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

The record establishes that a completed, non-randomized, open-label, single-group study enrolled 8 subjects and evaluated the MetaNeb® System. Its primary outcome was a Kelly chest X-ray score at approximately 48 hours after treatment initiation, with Day 2 scores described as compared with baseline. The radiographic scoring procedure and the exclusion of 3 subjects without measurable baseline atelectasis are also described.

The record does not report the primary outcome values or the results of the baseline comparison. It therefore does not show whether the Kelly score changed, how large any change was, how much subjects differed from one another, or how precisely a group estimate was measured. Results for the listed secondary outcomes are not reported in the registry record either.

Even if a within-group change had been reported, this design would not provide a randomized between-group contrast. In general, an observed change over time in a single-group study can reflect treatment, other care, natural changes in the condition, or measurement factors. The design cannot independently identify the contribution of treatment without an appropriate comparator and supporting assumptions.

The registry also does not report the analysis plan, handling of missing data, or multiplicity approach. Those omissions limit interpretation of any statistical claims that might otherwise be made. The posted safety counts show 0 serious adverse events, 0 other adverse events, and 0 deaths among the listed group, but these counts do not constitute a comparative safety assessment.

The study is informative about the intended measurement and the structure of the investigation. The registry record does not contain the outcome results needed to judge the direction, magnitude, or uncertainty of radiographic change. It therefore supports no conclusion about whether treatment changed atelectasis scores or about the cause of any change.

13. Why This Trial Matters Statistically

This study illustrates a distinction between a clearly described endpoint and a reported result. The registry identifies a measurement scale, its range and interpretation, the timing of the primary assessment, and how scores from each lung were combined for each subject. Those details help readers understand what the planned outcome represents. But without endpoint values and an analysis, the measurement plan cannot establish what was observed.

It also highlights the interpretive limits of a single-group before-and-after design. A baseline measurement allows within-subject change to be described, but it does not supply the counterfactual information that a concurrent control group can provide. In general, a change during treatment is not automatically attributable to treatment. Study design determines which comparisons can answer which questions.

The record’s distinction between open-label conduct and a blinded image reader is statistically relevant. Blinding the reader can limit one source of assessment bias, while the absence of a comparator and the lack of reported analysis details remain separate limitations. A single design feature does not resolve all potential sources of uncertainty.

Finally, the record describes exclusions from Kelly Score analyses and lists multiple outcome measures without reporting analysis populations, missing-data handling, multiplicity methods, or results. These are important elements for understanding how planned outcomes became statistical conclusions. The entry can therefore be useful as a case study in endpoint definition and reporting completeness, while offering no numerical basis for evaluating the primary outcome’s effect or precision.

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 small enrollment of 8 limits the amount of information available from the study. The registry does not report a sample-size justification or the rationale for the enrollment target. The planning illustration described in the record is not the trial’s design: it assumes equal allocation between two arms, whereas this study is single-group. Numerical planning results are not reported.

The non-randomized, open-label, single-group design has no concurrent comparator. The stated baseline comparison can describe change over time but cannot, on its own, distinguish treatment-associated change from other influences. A blinded reader is described for the Kelly scoring, but the record does not explain the blinding procedures or report reader agreement.

Three of the 8 subjects did not have measurable baseline atelectasis and were excluded from Kelly Score analyses. The registry does not report the final number analyzed, individual scores, the completeness of follow-up images, or the handling of missing assessments. It also does not report a statistical analysis plan, an inferential method, or a multiplicity strategy for the several outcome measures.

Most importantly, no primary outcome results or secondary outcome results are reported in the registry record. Without estimates and measures of uncertainty, the direction, magnitude, and precision of radiographic or other changes cannot be evaluated. Further details on eligibility, participant characteristics, actual treatment duration and frequency, and the scoring process are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: MetaNeb® Chest X-ray Study — NCT02871258.
• Registry record last updated 2024-09-24; status last verified 2024-08.
• Results first posted 2024-09-24.
• 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

NCT02871258 is a completed, single-group, non-randomized, open-label study of the MetaNeb® System, sponsored by Hill-Rom. Enrollment was 8, and the listed treatment was for a minimum of 48 hours or until earlier hospital discharge. The primary outcome was the Kelly chest X-ray score at approximately 48 hours after treatment initiation, described as compared with baseline.

The outcome description states that 3 of the 8 subjects had no measurable baseline atelectasis and were excluded from Kelly Score analyses. A blinded reader scored each lung, and the scores were averaged for each subject. The record lists 6 outcome measures but 0 analyses. It does not report primary or secondary outcome results, the analysis plan, or missing-data methods. Safety counts list 0 serious adverse events, 0 other adverse events, and 0 deaths among 8 subjects at risk.