Home Air Quality Impact for Adults With Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Home Air Quality Impact for Adults With Asthma (NCT05224076), a registered phase not stated study. The primary outcome is Episodes Per Day.

2. Clinical Question

These distinctions matter when interpreting the record. The study’s stated purpose encompasses monitoring, app-based reporting, and the relationship between exposure changes and symptoms, while the primary endpoint captures daily threshold-exceedance episodes. The record lists integration of study components and ecological momentary assessment surveys as secondary outcomes, but does not report their results. Consequently, it describes what the investigators intended to assess, not whether the monitoring approach was practical or whether measured air-quality changes coincided with symptom changes.

3. Trial Design

The registry identifies NCT05224076 as a completed feasibility study sponsored by the University of Kansas Medical Center. Its official title describes capturing momentary residential environmental exposures and asthma symptoms in adults in the changing COVID-19 landscape. The listed start date is 2022-03-30, the primary completion date is 2024-02-28, and enrollment is 64. The record’s status is completed.

The study’s brief summary focuses on whether home indoor air-quality monitoring and a smartphone app can be used to identify changes in air quality and how those changes affect adults with asthma. Home Air Quality is the named intervention, categorized as other. The registry lists integration of study components and ecological momentary assessment surveys as secondary outcomes. It does not describe the monitoring schedule for those secondary measures, the app workflow, or how participants were assigned to any groups.

The registry explicitly cautions that this is not a randomized comparison, that allocation is not stated, and that the arms are not a like-for-like control comparison. Therefore, any apparent group differences cannot be assumed to represent a randomized treatment contrast. The record does not report a comparator protocol, masking, recruitment setting, eligibility criteria, or whether participants contributed data to every measure.

The primary outcome was measured daily for 14 days. That repeated measurement structure is relevant to analysis: daily observations from the same participant may be related rather than independent. The record does not state how that dependence was handled. It also does not report a statistical analysis plan or analysis results. The completion status and enrollment figure describe the trial record, but do not establish that all enrolled participants completed monitoring, posted every survey, or were included in an outcome 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.

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 Episodes Per Day, measured over Measured daily for 14 days.

The primary endpoint is titled Episodes Per Day, with units of episodes per day. It is defined as the number of daily episodes in which residential VOCs exceeded 333 ppb and/or PM2.5 exceeded 15 mg/m3, measured by the Awair home air-quality monitor. The listed timeframe is measured daily for 14 days. The registry specifies a mean as the parameter and standard deviation as the dispersion measure.

As a rate outcome, this measure expresses the frequency of threshold-exceedance episodes over a unit of time. The daily scale makes it possible to describe how often monitored conditions crossed the stated thresholds during the measurement period. The “and/or” definition allows an episode to meet the VOC criterion, the PM2.5 criterion, or both; the record does not further explain how simultaneous exceedances or episode boundaries were handled.

Using a defined threshold can make an environmental measure easier to interpret than a continuous stream of monitor readings, because it focuses on the frequency of readings or events meeting a prespecified condition. That is a general feature of threshold-based endpoints, not a claim about the study’s observed results. The record does not report a mean episode rate, a standard deviation, or any comparison of rates.

This endpoint measures monitored air-quality conditions, not asthma symptoms or a clinical outcome. Although the study’s broader purpose concerns symptoms, the registered primary measure alone cannot establish whether participants felt better or worse, nor whether an exposure change caused a symptom change. Those questions would require the relevant symptom data and an analysis linking exposure and symptoms, which are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as a rate, with the parameter reported as a mean and the dispersion measure as a standard deviation. It gives a daily timeframe of 14 days and defines an episode by specified VOC or PM2.5 threshold exceedances. No analysis results or statistical analysis plan are reported in the registry record. The concepts below explain how methods of this kind are generally interpreted; they do not identify methods used in this study unless the registry explicitly states them.

What does a mean episode rate describe?

In general, a mean rate summarizes the average number of events per unit of exposure or time. Here the stated unit is episodes per day. A mean would give a central summary across the observations included in an analysis; it would not, by itself, show whether most participants had similar rates or whether a smaller number of observations had especially high rates. The standard deviation describes dispersion around the mean. It is not a confidence interval and does not directly express how precisely the mean has been estimated.

The registry identifies this as an event rate per unit of exposure. For rate data, the amount of time or other exposure contributing to the count matters. General rate analyses account for the opportunity to observe events, rather than treating every count as equally informative when observation time differs. The record says the outcome was measured daily for 14 days, but does not state how missing days or unequal monitoring time were handled, or what precise exposure-time denominator was used in an analysis.

Why can repeated daily observations matter?

In general, repeated observations from the same person tend to share features. A person’s readings on nearby days may be more alike than readings from different people. Treating all daily observations as independent when they are correlated can make uncertainty estimates too small. Statistical approaches for repeated measurements can account for within-person dependence, but the appropriate choice depends on the data structure and analysis question. The registry record does not report whether a repeated-measures model, participant-level summary, or another approach was used.

Count and rate outcomes can also show more variability than a simple model assumes. This is called over-dispersion: the observed variability exceeds what the model expects. In general, ignoring over-dispersion may make standard errors and confidence intervals unreliable. Analysts may use a model or variance adjustment suited to the data, but no model choice or over-dispersion assessment is reported in the registry record. It is not possible to infer the distribution of the recorded episodes from the endpoint definition alone.

How would uncertainty be read?

In general, a confidence interval gives a range of values compatible with the data and the chosen method under its assumptions. A narrower interval indicates greater precision than a wider interval, although precision is not the same as clinical importance or freedom from bias. A p-value evaluates compatibility with a stated null hypothesis under a statistical model; it does not measure the probability that a hypothesis is true. Neither confidence intervals nor p-values for the study’s outcomes are reported in the registry record, so no inference about statistical significance or precision can be drawn.

For comparisons, an estimate should be interpreted alongside its uncertainty, the groups being compared, the endpoint definition, and the analysis method. Here the record warns that allocation is not stated and the arms are not a like-for-like control comparison. That warning is important independently of any p-value: statistical adjustment cannot make an unspecified or non-equivalent comparison into a randomized one. No adjusted or unadjusted comparison estimate is reported.

What does the planning illustration represent?

The registry’s planning note describes an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It defines the target effect as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial used those assumptions to set enrollment. The registry does not report a sample-size justification for the study’s design.

In general, a sample-size calculation estimates how many participants or events would be needed under specified assumptions about the effect, variability, allocation, and statistical procedure. Such a calculation is conditional on those assumptions. A planning illustration is not observed power, and it cannot establish that the completed study had adequate precision. The posted planning values should be read as scenarios, not as participant results or evidence of an effect.

The planning note distinguishes participants per arm for ordinary outcomes from total events for time-to-event calculations. It identifies the latter as a Schoenfeld calculation. This distinction is general: participant-based calculations concern enrollment units, while event-based calculations for time-to-event analyses depend on the number of observed events. The registry’s primary endpoint is a daily rate, and the record does not state that a time-to-event analysis was conducted. No output value from the planning illustration is reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures. It names Episodes Per Day as the primary outcome and lists Integration of Study Components and Ecological Momentary Assessment (EMA) Surveys among the secondary outcomes. The record does not report the full outcome definitions and results for every measure, or a plan for controlling the chance of false-positive findings across multiple outcomes or comparisons. A multiplicity plan is not reported in the registry record.

In general, testing several outcomes or contrasts can increase the chance that at least one result appears statistically notable by chance. Analysts may prespecify a primary outcome, adjust inference across tests, or clearly distinguish confirmatory from exploratory analyses. The registry’s primary designation helps identify the outcome of greatest stated priority, but it does not reveal what inferential procedure was used. With 0 analyses listed, there are no posted estimates or tests to evaluate.

Missing-data handling is not reported in the registry record. This matters because the primary measure was collected daily for 14 days, while app-based ecological momentary assessment surveys are also listed. The record does not give completion rates, missing-day counts, reasons for missing measurements, or methods for handling missingness. It also does not state whether analyses used all enrolled participants, only participants with complete data, or another analysis population.

In general, missing observations can affect both the precision and the interpretation of results, particularly when the likelihood of missingness is related to participant characteristics, symptoms, or measured exposures. That is a methodological concern, not evidence that missing data occurred in this study. The available record does not permit an assessment of the extent or consequences of missingness, the analysis population, or the prespecification of outcome analyses.

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’s adverse-event information lists a study group with 40 participants at risk for serious adverse events and 0 affected. Its other-adverse-event figures list 40 at risk and 0 affected. The record reports 0 deaths, and no top serious adverse-event terms are listed.

These entries describe what is recorded in the registry’s adverse-event display. They should not be read as proof that no symptoms, discomforts, or other events occurred: the displayed categories concern reported adverse-event counts, and the registry does not provide event narratives or additional context. The record also does not explain the relationship between the at-risk denominators and the enrollment figure, or provide a separate account of monitoring and reporting procedures.

Zero affected in the displayed categories means that no events are recorded for those categories in this entry; it does not establish the absence of every possible adverse experience. The serious-event, other-event, and death figures should be interpreted as registry reports, not as a broader assessment of safety or a comparison between groups. No safety rate or comparative safety estimate is reported.

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

The registry record describes a feasibility study intended to assess home air-quality monitoring and smartphone-based reporting among adults with asthma. It defines a primary measure of daily episodes in which monitored VOC or PM2.5 levels exceeded specified thresholds. It also lists integration of study components and ecological momentary assessment surveys as secondary outcomes. These details clarify the questions the study was designed to address, but they do not show what the study found.

The record does not report outcome values, symptom results, estimates of association, confidence intervals, p-values, or analyses. It therefore cannot establish whether monitoring was feasible, how often threshold-exceedance episodes occurred, or whether changes in air quality were associated with changes in symptoms. The completed status and enrollment figure do not fill that results gap.

The endpoint is an environmental measure rather than a direct clinical outcome. A higher or lower episode rate, if reported, would need to be interpreted as a difference in monitored threshold crossings and not automatically as a difference in asthma symptoms. Establishing a relationship between exposure and symptoms would require relevant symptom data and a reported analysis that addresses the timing and dependence of observations.

The record’s warning that the study is not a randomized comparison and that the arms are not like-for-like also matters. Even if a group difference were available, the registry entries would not justify treating it as a randomized causal effect. General statistical adjustment can address some measured differences under appropriate assumptions, but it cannot replace clear design information or remove every source of bias.

The most defensible reading is therefore limited: the registry documents a completed feasibility study, its intended monitoring approach, and a threshold-based primary endpoint. It does not report evidence sufficient to judge operational feasibility or an effect on symptoms. No treatment recommendation or conclusion about clinical benefit follows from the record.

13. Why This Trial Matters Statistically

This study raises a useful statistical question about measuring environmental exposure in everyday settings: how to summarize threshold crossings that may vary from day to day and from household to household. A daily episode rate provides a defined outcome that can be related to the monitoring period. Pairing monitoring with momentary surveys also reflects the challenge of aligning environmental measurements with reports made during ordinary life.

Those strengths of the question make measurement and analysis details especially important. Repeated observations from a participant are not necessarily independent, and air-quality readings may vary over time. A clear account of episode definitions, monitoring completeness, survey completion, and the handling of within-person dependence would help readers judge whether the resulting summaries are precise and interpretable. The registry defines the threshold-based endpoint but does not report those analysis details.

The feasibility framing is also statistically relevant. Before interpreting an exposure-symptom relationship, readers need to know whether the monitoring and survey components generated usable data and how much information was available for analysis. Enrollment alone cannot answer those questions. The registry lists integration of study components and ecological momentary assessment surveys as secondary outcomes, but their results are not reported.

Finally, the record explicitly warns against interpreting the arms as a like-for-like control comparison. That design context is essential to distinguish descriptive patterns from causal effects. Because no analyses or outcome results are posted, this record is most informative about the intended measurement problem and the limits on interpretation. It does not establish the success of the approach or the clinical meaning of any exposure pattern.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record leaves important design and reporting details unavailable. It does not state allocation, define a like-for-like comparator, describe participant eligibility or characteristics, or report how group membership was determined. It cautions that the study is not a randomized comparison and that the arms are not equivalent controls. These gaps prevent interpretation of any potential arm contrast as a controlled intervention effect.

The primary endpoint is defined by threshold exceedances, but the record does not explain how episodes were segmented, how simultaneous VOC and PM2.5 exceedances were counted, or how periods with missing monitor data were treated. It reports daily measurement for 14 days, but not the distribution of completed observations or the monitoring completeness. These omissions limit understanding of the outcome’s construction and the information available for analysis.

Outcome results and statistical methods are not reported; the registry lists 0 analyses. There is no posted estimate of the mean daily rate or its standard deviation, no uncertainty interval, and no reported analysis connecting exposure with symptoms. The record also does not provide missing-data methods, analysis populations, a multiplicity plan, or a sample-size justification. Enrollment of 64 alone cannot establish the precision or adequacy of an analysis.

These are limitations of what the registry record documents. They do not establish that data collection or analysis was unsuccessful. They do mean that readers cannot evaluate completeness, reproducibility, the robustness of estimates, or the extent to which the feasibility aims were met from this record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Home Air Quality Impact for Adults With Asthma — NCT05224076.
• Registry record last updated 2025-07-29; status last verified 2025-07.
• Results first posted 2025-07-29.
• 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

NCT05224076, titled Home Air Quality Impact for Adults With Asthma, is listed as completed. The official title describes a feasibility study to capture momentary residential environmental exposures and asthma symptoms in adults. The sponsor is the University of Kansas Medical Center. The registry reports enrollment of 64, a start date of 2022-03-30, and a primary completion date of 2024-02-28.

The study’s brief summary concerns the practicality of home indoor air-quality monitoring and a smartphone app. Its primary outcome is Episodes Per Day, defined by VOC or PM2.5 threshold exceedances and measured daily for 14 days. Integration of study components and ecological momentary assessment surveys are listed as secondary outcomes.

The registry lists 0 analyses and does not report outcome results. It also cautions that the study is not a randomized comparison, allocation is not stated, and the arms are not a like-for-like control comparison. The record describes the study’s aims and measurement but does not permit conclusions about feasibility or symptom effects.