Utilizing Exhaled Breathe Condensate Collection to Study Ion Regulation in Cystic Fibrosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Utilizing Exhaled Breathe Condensate Collection to Study Ion Regulation in Cystic Fibrosis (NCT01880723), a non-randomized na study. The primary outcome is Exhaled Sodium (mmol/L).

2. Clinical Question

The study’s stated hypothesis was that EBC chloride and sodium would be lower in CF participants at baseline, and that albuterol would decrease EBC sodium and increase EBC chloride. These are hypotheses, not reported findings. The primary outcome named in the record is exhaled sodium, measured in mmol/L and summarized as a mean with standard deviation. Although the stated aims include both sodium and chloride, the registry does not provide numerical outcome results for either ion.

The central comparison has important design limits. The study was not randomized, masking was absent, and saline was described for healthy participants only. The registry record does not report a randomized, like-for-like treatment comparison. It therefore does not establish that any difference in measurements would be attributable to albuterol rather than population characteristics, study procedures, or other factors.

3. Trial Design

This completed study is registered as NCT01880723, with the title “Utilizing Exhaled Breathe Condensate Collection to Study Ion Regulation in Cystic Fibrosis.” Its official title is “Modifying Genes in Cystic Fibrosis: The Beta-2 Adrenergic Receptors and Epithelial Na+ Channels.” The sponsor is the University of Arizona. The listed phase is NA. The registry gives a start date of 2009-05 and a primary completion date of 2012-07.

The design is described as nonrandomized, unmasked, and single group. Enrollment is listed as 32. The study includes CF and healthy participants, but the record does not fully describe how participants were assigned to the listed intervention groups, how many received each intervention, or whether all enrolled participants contributed outcome data. Those details are not reported in the registry record.

The intervention descriptions list albuterol and placebo saline. The arm description specifies albuterol at 2.5 mg diluted in 3mL normal saline, nebulized using a Power Neb2 nebulizer. Saline is described as nebulized 3 ml normal saline using the same named device, for healthy participants only. Given the nonrandomized design and the restriction of the saline description to healthy participants, this should not be read as a randomized comparison of albuterol with saline within both populations.

Participants breathed on a Jaeger EcoScreen for 20 minutes to collect EBC samples. The primary outcome description states that samples were collected before and 30-, 60-, and 90-minutes following albuterol administration. The registry lists secondary outcomes of diffusion capacity of the lungs for carbon monoxide, diffusion capacity of the lungs for nitric oxide, and peripheral oxygen saturation. Although the record lists five outcome measures, it does not give numerical results or analysis details for them.

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 Exhaled Sodium (mmol/L), measured over up to 90-minutes post albuterol.

The primary endpoint is exhaled sodium in EBC, measured in mmol/L. The registry specifies a mean as the summary measure and standard deviation as the measure of dispersion. EBC is collected while participants breathe on a Jaeger EcoScreen for 20 minutes; the endpoint description identifies collection before and 30-, 60-, and 90-minutes following albuterol administration.

The study uses this measurement to investigate ion regulation in CF and healthy participants and to assess changes around albuterol administration. The stated rationale is that EBC could detect differences in ion regulation between the populations. The record’s hypothesis specifically predicts lower baseline EBC chloride and sodium in CF, followed by decreased sodium and increased chloride after albuterol. These predictions describe the research question; they do not establish that the predicted patterns occurred.

In general, a mean describes the average measurement in the analyzed observations, while a standard deviation describes how dispersed those observations are around the mean. Both help characterize a continuous outcome, but neither alone describes the precision of an estimated treatment effect. The registry does not report the actual sodium means, standard deviations, analyzed sample sizes, or comparisons at the stated collection times. It also does not report a numerical estimate of change from baseline. As a result, the endpoint’s observed magnitude and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins with identifying the outcome, its scale, and the comparison the design can support. The primary outcome is exhaled sodium, a continuous measurement expressed in mmol/L. The registry specifies a mean and standard deviation. This identifies the planned style of summary, but it does not provide the observed summaries or explain which statistical test or model was used. The analysis method is not reported in the registry record.

What does a mean and standard deviation describe?

In general, a mean is the arithmetic average of the measured values in the analysis set. A standard deviation describes how much individual measurements vary around that average. The mean answers a question about the center of the observed measurements; the standard deviation describes their spread. The standard deviation is not the same as the standard error, which concerns the precision of an estimated mean. Neither summary alone establishes whether a change or difference is statistically distinguishable from sampling variation.

Here, those summaries would be relevant at the collection times named in the outcome description and across the CF and healthy populations. Yet the record gives no corresponding mean, standard deviation, or outcome-specific participant count. It is therefore not possible to assess within-group variation, compare the observed distributions, or determine how much precision the summaries might have had.

How should repeated measurements be considered?

The endpoint description specifies measurements before albuterol and at 30-, 60-, and 90-minutes afterward. In general, measurements from the same participant over time are related: they are not independent observations in the way measurements from unrelated individuals may be. An analysis of change over time should account for that within-participant relationship. Depending on the design and data, an analysis might compare changes from baseline or model measurements across time, but the registry does not identify which approach was used. It is not appropriate to infer a repeated-measures model or a particular contrast from the collection schedule alone.

The description also refers to CF and healthy participants, which raises a distinction between changes over time within a population and differences between populations. These are different questions. A change after albuterol in one population is not the same estimand as a difference in response between populations. The record does not report an analysis defining or estimating such contrasts. It also does not report whether any adjustment variables were considered.

What would an estimate of effect and its uncertainty add?

In general, an effect estimate states the direction and magnitude of a comparison, while a confidence interval communicates its statistical uncertainty under the model assumptions. A p-value addresses compatibility of the observed data with a specified null hypothesis and model; it does not measure the probability that the hypothesis is true, nor does it express clinical importance. These measures are useful only when the comparison, analysis population, and model are adequately described. The registry lists no analysis results, effect estimates, confidence intervals, or p-values.

For continuous outcomes, interpretation can also depend on whether the distribution is reasonably represented by the selected summary and model. In general, skewness, outliers, or unequal variability may make a simple mean-based comparison less informative or affect model assumptions. The registry record does not describe the observed sodium distribution, diagnostic checks, transformations, or alternative analyses. It is therefore not possible to evaluate those assumptions for this study.

What do the planning assumptions mean?

The registry describes sample-size planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says the effect to detect is expressed as a stated fraction of the observed effect. Such illustrations are planning calculations, not evidence that the study achieved a particular power and not a substitute for observed results. The numerical sample-size illustrations are not reported in the registry record. The record also does not report the study’s original design justification, so these illustrations should not be treated as the trial’s original enrollment rationale.

In general, sample-size planning depends on assumptions about the target effect, variability, significance threshold, allocation, and analysis. If those assumptions differ from the eventual design or observed data, the planning calculation may not describe the precision achieved. No observed effect value or outcome variability is reported, so the planning assumptions cannot be independently evaluated from the registry record.

Why does the design matter for the analysis?

Because allocation was nonrandomized and the registry describes a single-group model, the study should not be interpreted as a randomized controlled trial. Saline is described for healthy participants only, not as a matching control condition across both populations. In general, random allocation can help balance measured and unmeasured prognostic factors between treatment groups; absent randomization, observed differences may reflect differences in who received each condition as well as treatment exposure. Masking is listed as none, so the record does not indicate protection against awareness influencing measurement or conduct.

The record lists zero analyses and does not describe a statistical analysis plan. It does not report whether analyses were adjusted, how repeated measurements were handled, or how missing observations were addressed. Without those details and the numerical results, statistical interpretation must remain descriptive of the registered design and stated question.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures, including exhaled sodium as the primary outcome and secondary outcomes involving lung diffusion capacity for carbon monoxide, lung diffusion capacity for nitric oxide, and peripheral oxygen saturation. It does not report an analysis plan specifying how these outcomes were tested or interpreted together. The multiplicity strategy is not reported in the registry record.

In general, when several outcomes, time points, or contrasts are examined, the chance of obtaining at least one apparently notable result by chance can increase if each is assessed without accounting for the overall set of analyses. A prespecified hierarchy, adjustment procedure, or clear distinction between primary and exploratory analyses can help readers understand that risk. The record names a primary outcome and describes multiple collection times, but does not report how comparisons across time or populations were handled. No correction or other multiplicity approach should be inferred.

The registry lists enrollment but does not provide outcome-specific denominators or counts of missing measurements. A missing-data method, reasons for missingness, and analysis population definitions are not reported in the registry record. In general, missing observations can affect both precision and the interpretation of estimates, particularly when the likelihood of missingness is related to participant characteristics or measurements. Without the pattern and handling of missing data, the representativeness of available measurements cannot be assessed.

The record also does not report whether analyses included all enrolled participants, only participants with available measurements, or another defined population. No imputation strategy, sensitivity analysis, or protocol-deviation handling is described. These omissions limit reproducibility and prevent assessment of whether the analysis population matched the registered question.

11. Safety Results

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

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 serious adverse event figures separately for the Healthy and Cystic Fibrosis groups. For each group, the serious-event count is 0 among 16 at risk. Other adverse events are listed as 0 among 16 at risk for each group. These figures describe the entries in the registry record; they do not provide event descriptions, timing, or an account of how events were collected.

The deaths field is null for both groups, so death information is not reported in the registry record. The list of top serious adverse event terms is empty. An empty term list does not add detail about the monitoring process or establish that every possible event was assessed in the same way.

In general, a recorded count of zero is not proof that an intervention has no risk. It is a count within the recorded study groups and observation period, and its interpretation depends on how safety events were defined, sought, and followed. The registry does not report the safety observation period, event definitions, or a detailed safety analysis. The figures should therefore be read narrowly as the recorded counts, not as a comprehensive estimate of safety or a comparison demonstrating a treatment effect.

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

The registry record establishes that investigators studied EBC collection in CF and healthy participants, with an interest in ion regulation and albuterol. It specifies exhaled sodium as the primary endpoint, gives the collection procedure and timing, and records the study as completed. It also names secondary outcomes and records adverse-event counts. These details describe the intended research question and some elements of its conduct.

The record does not report numerical results for the primary endpoint or secondary outcomes. It therefore does not show whether EBC sodium differed between populations, whether sodium changed after albuterol, or whether the stated ion hypotheses were supported. No effect estimate or measure of its precision is available in the registry record. This means that neither the size nor the direction of the primary finding can be interpreted from the posted information.

The design also limits the comparisons that could be drawn. Nonrandomized allocation, no masking, and saline described only for healthy participants do not form a like-for-like randomized treatment comparison. Even if measured values had been reported, a difference could not automatically be attributed to albuterol. Population differences, selection into study conditions, measurement procedures, and other unreported factors would need consideration.

In general, a completed study record and an enrollment figure do not by themselves establish that all registered outcomes were analyzed or that the results are precise. Readers need outcome values, analysis populations, denominators, methods, and uncertainty estimates to assess the evidence. Those details are not reported in the registry record. The listed safety counts are limited to the recorded groups and should not be read as proof that there is no risk.

Thus, the record is informative about the study’s aims, design, measurement schedule, and selected administrative details, but it does not allow a conclusion about the observed clinical or statistical result. It also cannot establish that EBC is a validated measure of ion regulation or that albuterol caused a change in EBC ions.

13. Why This Trial Matters Statistically

This study raises a useful measurement question: whether EBC can capture ion-regulation patterns in CF and healthy participants, and whether measurements vary after albuterol. Statistically, that question involves both group differences and measurements over time. Defining the intended contrast matters because a baseline population difference, a within-participant change after administration, and a difference in change between populations are not interchangeable quantities.

The registry’s description also illustrates why design and analysis details are essential to interpretation. Nonrandomized allocation and the absence of masking affect how confidently observed differences could be attributed to treatment. The saline condition is described for healthy participants only, which limits the comparator structure. A clear analysis plan would be needed to explain how population, intervention, and collection time were related in the statistical comparisons.

Continuous measurements such as exhaled sodium are best understood through both their central estimates and variability, with uncertainty around the comparison. Repeated observations from the same participant require attention to their dependence. In general, a suitable model and transparent reporting of the analysis population, missing observations, and uncertainty can help readers distinguish a measurable pattern from an imprecise or potentially biased estimate.

The record names the primary outcome and collection schedule, but numerical results and analysis details are not reported in the registry record. That gap is itself important for statistical reading: a stated hypothesis cannot be treated as an observed effect, and a completed status does not reveal the estimate or its precision. The record supports discussion of the study’s design and statistical questions, but not a quantitative conclusion about EBC sodium or albuterol.

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.

Several limitations arise from the registered design and reporting. Allocation is nonrandomized, masking is listed as none, and the model is described as single group. The saline intervention is specified for healthy participants only. Consequently, the record does not describe a randomized, masked, like-for-like comparison of albuterol with saline across the two populations. Causal interpretation of any treatment-associated change would therefore be limited even if outcome estimates were available.

The registry does not report the numerical primary outcome or the secondary outcome results. It also does not provide outcome-specific denominators, participant flow, analysis populations, missing-data methods, or the statistical analysis plan. This prevents assessment of attrition, data completeness, analytical choices, and the precision of estimates. The record lists five outcome measures, but does not describe how analyses across outcomes or collection times were addressed.

The primary endpoint description gives the measurement procedure and collection timing, but does not report the actual values, distribution, or measurement-quality information. The registry does not describe protocol deviations, adherence, or whether measurement procedures differed across populations. These details are not reported in the registry record and should not be assumed.

Enrollment is listed as 32, while the adverse-event groups each list 16 at risk. The record does not explain the relationship between these entries or identify outcome-analysis denominators; no inference about participant overlap, completion, or analysis counts is warranted. Finally, the listed adverse-event counts lack a reported observation period and detailed event-collection methods. Together, these reporting gaps prevent a complete assessment of statistical robustness and study conduct.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Utilizing Exhaled Breathe Condensate Collection to Study Ion Regulation in Cystic Fibrosis — NCT01880723.
• Registry record last updated 2023-11-29; status last verified 2023-11.
• Results first posted 2014-06-25.
• 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

NCT01880723 is a completed, nonrandomized, unmasked study sponsored by the University of Arizona, with a single-group model and enrollment listed as 32. The registry gives a start date of 2009-05 and a primary completion date of 2012-07. It concerns EBC ion regulation in CF and healthy participants, with albuterol administration and saline described for healthy participants only.

The primary endpoint is mean exhaled sodium in mmol/L, with standard deviation specified as the dispersion measure. EBC collection involved breathing on a Jaeger EcoScreen for 20 minutes, with samples described before and 30-, 60-, and 90-minutes after albuterol. The registry names three secondary outcomes involving lung diffusion capacity and peripheral oxygen saturation.

Numerical outcome results, analysis methods, and analysis populations are not reported in the registry record. The record lists 0 serious adverse events and 0 other adverse events among 16 at risk in each of the Healthy and Cystic Fibrosis groups; death information is not reported.