IL-17 Neutrophils in CF Lung Inflammation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for IL-17 Neutrophils in CF Lung Inflammation (NCT02025829), a registered phase not stated study. The primary outcome is Change in Sputum IL-17 Neutrophils.

2. Clinical Question

The stated scientific aim was to assess whether IL-17-positive polymorphonuclear leukocytes are present in the cystic fibrosis airway, correlate with lung-function measures, and decrease in patients receiving intravenous antibiotics for a pulmonary exacerbation. These are linked but distinct questions: detection concerns whether the cells are present, correlation concerns whether two measures vary together, and change concerns whether the sputum measure differs between the two sampling occasions.

The registry record also describes a clinically stable arm. However, it states that studies of sputum neutrophils during clinical stability were not undertaken because very few neutrophils at the end of treatment for a pulmonary exacerbation were positive for IL-17. The record therefore does not describe a stable-cohort primary endpoint analysis that could serve as a direct comparison with the before-and-after assessment in the exacerbation cohort.

The record lists cystic fibrosis as the condition and an enrollment of 14. It does not report numerical findings for the primary question, the relationship with FEV1, or the presence of IL-17-positive cells. The research question can be described from the registry, but the posted record does not establish what the measurements showed.

3. Trial Design

NCT02025829, titled “IL-17 Neutrophils in CF Lung Inflammation,” is listed as completed. The registry record gives University Hospitals Cleveland Medical Center as the sponsor, with a study start of 2014-02 and primary completion of 2014-12. Enrollment is listed as 14. These details describe the registered study, not the number of participants contributing to each outcome analysis.

The record describes clinically stable and exacerbation cohorts. The stable cohort description refers to participants with cystic fibrosis and lists 10 subjects with one copy of F508del and 4 subjects with at least one copy of G551D. The exacerbation cohort description refers to participants admitted for intravenous antibiotic treatment of a pulmonary exacerbation and lists 10 subjects with one copy of F508del. The registry does not explain how these cohort descriptions relate to the total enrollment or the smaller safety populations recorded elsewhere.

The primary outcome description focuses on the exacerbation cohort. Participants were to provide sputum at the beginning and completion of intravenous antibiotic treatment, and each participant was described as their own control. The record says the percentage of sputum neutrophils positive for IL-17 was measured by flow cytometry. It also describes comparing sputum IL-17 neutrophil counts with change in FEV1 measured by spirometry.

This is not described as a randomized comparison. The registry’s caution states that allocation was not stated and that the arms are not a like-for-like control comparison. The within-participant before-and-after comparison is the clearest design feature for the primary outcome; it should not be interpreted as a randomized treatment-versus-control contrast.

The record lists three outcome measures and zero analysis entries. It does not report a protocol-level statistical analysis plan, allocation procedures, or a sample-size justification. The description of the endpoint and sampling occasions alone does not establish which statistical test or model was used, whether all planned measurements were collected, or which participants contributed to any 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

Analysis population for the primary outcome, as defined in the registry: Regarding "Clinically Stable" Arm: Because very few neutrophils at the end of treatment for a pulmonary exacerbation were positive for IL-17, it was determined not to undertake studies examining sputum neutrophils during periods of clinical stability.

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 Change in Sputum IL-17 Neutrophils, measured over End of Treatment, two weeks. Samples will be obtained from each study volunteer at the beginning of IV antibiotic treatment and at the completion of antibiotic treatment for a pulmonary exacerbation.

The primary endpoint is titled “Change in Sputum IL-17 Neutrophils.” It measures the percentage of neutrophils in sputum that are positive for IL-17, with the measurement expressed as a percentage of neutrophils. The registry identifies the summary parameter as a mean and the dispersion measure as a standard deviation. The assessment is based on flow cytometry of sputum collected from participants in the exacerbation cohort at the beginning and completion of intravenous antibiotic treatment.

This endpoint is used to quantify an inflammatory cell feature in the airway. In the study’s stated rationale, IL-17-positive polymorphonuclear leukocytes may be relevant to cystic fibrosis lung inflammation. Measuring their proportion among sputum neutrophils gives a defined outcome for assessing whether that feature changes across the treatment period. The registry also proposes examining how the sputum measure relates to change in FEV1, a lung-function measure recorded by spirometry.

In general, reporting a mean describes the average measurement across the participants included in an analysis, while a standard deviation describes how dispersed individual measurements are around that average. The mean and standard deviation do not, on their own, show the size or precision of a before-and-after change. A change estimate and an uncertainty interval would be needed to describe those aspects directly.

The record states a two-week end-of-treatment timeframe and describes samples at the beginning and end of treatment. It does not report the actual endpoint values, the observed change, a confidence interval, or an analysis result. Thus, the endpoint’s definition and intended use are recorded, but its numerical findings are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure summarized by a mean and standard deviation. The underlying measurement is a percentage: the fraction of sputum neutrophils identified as positive for IL-17 by flow cytometry, expressed as a percentage of neutrophils. The intended comparison is between measurements from the same participant at the beginning and end of intravenous antibiotic treatment for a pulmonary exacerbation.

What does a within-participant comparison mean?

In general, repeated measurements from the same person are linked rather than independent. A paired analysis evaluates the change within each participant, then summarizes those participant-level changes. This can be useful when participants differ from one another at baseline, because each participant contributes their own reference measurement. The registry describes participants as their own controls, but it does not state which paired statistical method, if any, was used. The actual analysis method is not reported in the registry record.

A paired comparison also depends on the availability of both measurements for a participant, unless the analysis uses a method that can appropriately handle incomplete repeated observations. The record does not say how many participants had measurements at both time points, how missing samples were handled, or whether the analysis included every enrolled participant. The intended paired structure therefore should not be mistaken for evidence that every participant posted a complete pair.

What do the mean and standard deviation describe?

In general, the mean is an average across observed measurements. The standard deviation describes the spread of those measurements around the mean. A standard deviation is not a confidence interval and does not by itself express the precision of a mean estimate. To interpret a before-and-after result, readers would usually need the estimated change and an uncertainty measure, such as a confidence interval, together with the number of participants contributing data. Those values are not reported in the registry record.

The measured outcome is a percentage, which is bounded: it cannot fall below zero or exceed the full percentage of neutrophils. In general, bounded measures may have distributions that are asymmetric or concentrated near a boundary. Whether that matters depends on the observed data and the analysis. The registry does not report the distribution of individual measurements or explain how the analysis addressed the bounded scale. It would be speculation to say that a particular transformation or model was used.

How should the FEV1 relationship be understood?

The endpoint description says sputum IL-17 neutrophil counts would be compared with change in lung function, measured by FEV1 using spirometry. In general, a correlation describes how two variables vary together; it does not by itself establish that one causes the other. A correlation can also depend on the range of measurements and on which participants have complete data for both variables. The registry does not report a correlation estimate, its uncertainty, the number of paired observations used, or a statistical method for this relationship.

The record identifies the spirometry procedure as following American Thoracic Society standards. That procedural description does not supply the resulting FEV1 values or specify the statistical model used to relate FEV1 change to the sputum measure. The timing and definition of the FEV1 change are not described in further statistical detail in the registry record.

What can be inferred from the sample-size assumptions?

The registry describes sample-size planning illustrations based on an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. In general, such illustrations ask how many participants per arm might be needed to reach a chosen power under specified assumptions. They are planning calculations, not evidence that a study had that power after data collection.

The record does not report a protocol sample-size justification or say that these planning assumptions governed the study’s design. It also does not report numerical values for the observed effect used in the illustration or the resulting participant counts. Therefore, those assumptions cannot be used to reconstruct the study’s planned or achieved precision. The illustration is not observed power, and it cannot substitute for an estimated effect with uncertainty.

More generally, power calculations depend on assumptions about the effect size, variability, significance threshold, allocation, and statistical model. If these assumptions differ from the observed study conditions, the calculation may not describe actual operating characteristics. In this case, the registry record gives some illustration assumptions but does not report enough numerical results to evaluate them against observed outcomes.

Which analysis method was used?

The statistical analysis method is not reported in the registry record. The description of a mean and standard deviation is not enough to identify a test, a model, or an adjustment strategy. The record lists zero analysis entries, so no statistical result should be inferred from the endpoint definition alone. In general, a complete interpretation would consider the estimate, its uncertainty, the number of observations, the handling of repeated measures and missing data, and any prespecified analytic choices. Those details are unavailable in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Begining of Exacerbation", "End of Exacerbation")
n   <- c(11, 11)
m   <- c(55, 4)
sp  <- c(23, 9)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Begining of Exacerbation  11  55.000  23.000  39.548  70.452
CARM  End of Exacerbation  11  4.000  9.000  -2.046  10.046

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, including two descriptions of sputum inflammatory mediators. It does not report a multiplicity plan, a hierarchy of outcomes, or whether any p-values or confidence intervals were adjusted for examining multiple outcomes. When several outcomes are assessed, the chance of at least one apparently unusual result can increase if each is interpreted without considering the number of comparisons. In general, a prespecified strategy can clarify which outcome is primary and how other outcomes are interpreted. The registry record does not describe such a strategy.

The primary endpoint is identified, but zero analysis entries are listed. No analysis population, participant flow for outcome data, or number contributing to the primary endpoint is reported. The record does not state whether the analysis was intention-to-treat, per-protocol, based on available observations, or defined in another way. These labels should not be assigned without documentation.

Missing-data handling is not reported in the registry record. The endpoint description specifies sampling at the beginning and completion of treatment, but does not say whether all samples were obtained, how incomplete pairs were handled, or whether any imputation was performed. In general, missingness can affect both the estimate and its uncertainty, especially when the reason a measurement is unavailable is related to the outcome. The direction and size of any such effect cannot be assessed without information about the missing observations and analysis.

The registry also does not report interim analyses, stopping rules, or a statistical analysis plan. Their absence from the record is not evidence that a particular procedure was or was not used; these details are not reported in the registry record.

12. 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’s adverse-event entries list zero serious adverse events among 3 participants at risk in the clinically stable group and zero among 11 participants at risk in the exacerbation group. For other adverse events, the entries likewise list zero affected among 3 at risk in the clinically stable group and zero affected among 11 at risk in the exacerbation group. The registry does not list serious adverse-event terms, and deaths are recorded as null rather than as a numerical count.

These entries describe the recorded safety counts, not proof that no adverse events occurred beyond the scope or reporting rules of the registry. A count of zero affected means that no affected participants are listed in that category for the stated group; it does not establish that an event is impossible or that the treatment has no risk. In general, safety estimates based on small groups have limited precision, and absence of a recorded event does not rule out uncommon events.

The safety populations shown in the registry do not match the overall enrollment of 14 in a way that the record explains. The clinical cohort descriptions also list different subject counts from the adverse-event entries. The reasons for these differences, including whether they reflect eligibility, exposure, reporting, or follow-up, are not reported in the registry record. The safety figures should therefore be read as the registry’s stated counts, not as a complete account of participant disposition or exposure.

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

The study addresses a focused biological measurement: the percentage of sputum neutrophils positive for IL-17 in people with cystic fibrosis, with particular interest in measurements before and after intravenous antibiotic treatment for a pulmonary exacerbation. It also raises the question of whether changes in that sputum measure relate to changes in FEV1. These questions are relevant to understanding airway inflammation as a measured phenomenon, but the registry record does not report results that answer them.

The record does not give the observed percentage at either sampling occasion, an average within-person change, or a measure of uncertainty. It also gives no reported estimate for the relationship between IL-17-positive neutrophils and FEV1. As a result, the posted registry information cannot establish whether the endpoint increased, decreased, or remained similar, or how consistent any change was across participants.

Even if numerical associations were available, a relationship between two measured variables would not by itself show that one causes the other. Similarly, a before-and-after change during treatment would not alone separate the effect of treatment from other changes over time, because this is not described as a randomized comparison and there is no like-for-like control arm for the primary endpoint. Those general considerations matter when interpreting this type of design; they do not imply a particular result for this study.

The registry’s description of the clinically stable group does not provide a direct comparison for the primary endpoint, because it states that stable-period sputum neutrophil studies were not undertaken. The cohort labels therefore should not be read as evidence of a stable-versus-exacerbation contrast in IL-17-positive neutrophils.

The record establishes the study’s objective, enrollment, cohort descriptions, endpoint, and planned sampling context. It does not establish whether IL-17-positive cells were present at a particular level, whether their percentage changed during treatment, or whether that change tracked lung function. Those conclusions would require numerical outcome data and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically interesting because it combines a repeated measurement within participants with a biological outcome expressed as a percentage. A within-person design can make a direct comparison across time while accounting for stable differences between participants. At the same time, it requires careful attention to paired observations, incomplete measurements, and the variability of participant-level changes. The registry describes the repeated-measure structure but does not report the analysis used or the data needed to evaluate it.

The endpoint also illustrates why a clear measurement definition matters. The outcome is not simply an IL-17 concentration: it is the percentage of sputum neutrophils positive for IL-17, measured by flow cytometry. The registry separately names sputum inflammatory mediators among secondary outcomes. Keeping these measures distinct is necessary when interpreting what biological quantity a result would represent.

The study further proposes relating the sputum measure to change in FEV1. This highlights a common statistical distinction: describing change in one outcome and assessing its association with change in another are separate analyses, each with its own assumptions and uncertainty. The registry states both interests, but reports no results for either.

Finally, the record illustrates the difference between an outcome definition and an evidence statement. A registered objective, a specified timeframe, and a completed status do not provide an estimated result. With zero analysis entries and no numerical outcome findings reported, statistical interpretation must remain limited to the design and the questions the study set out to address.

15. 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 most important limitation for interpreting the registry record is the absence of numerical outcome results. Although the primary measure and sampling plan are described, the record does not report participant-level data, group summaries, a mean change, an uncertainty interval, or a test result. This prevents assessment of direction, magnitude, variability, and precision.

The record also does not identify the statistical analysis method, the number of participants contributing paired samples, or the analysis population. Missing-data procedures, protocol deviations, and reasons for incomplete measurements are not reported. Without these details, it is not possible to assess whether the analyzed observations represent all enrolled participants or how incomplete follow-up may have affected the findings.

The study has an enrollment of 14, and its cohort descriptions and safety populations contain different counts. The registry does not reconcile those counts. The exacerbation cohort is described as the focus of the primary endpoint, while the record says sputum neutrophil studies during clinical stability were not undertaken. Thus, the stable cohort cannot be treated as a reported parallel control for the primary measure.

The registry states that the arms are not a like-for-like control comparison and that allocation was not stated. The before-and-after design can describe changes over the treatment period, but the record does not describe a randomized control contrast that would isolate treatment effects from other temporal influences. The relationship between the sputum outcome and FEV1 is also not reported.

Finally, multiplicity handling, an interim-analysis plan, and the protocol’s sample-size justification are not reported in the registry record. The planning assumptions listed there do not provide observed precision or replace outcome estimates. These limitations concern what can be concluded from the registered record; they do not establish that unreported analyses or procedures were absent from the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: IL-17 Neutrophils in CF Lung Inflammation — NCT02025829.
• Registry record last updated 2019-02-15; status last verified 2019-01.
• Results first posted 2017-03-24.
• 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.

19. Record Summary

NCT02025829 is a completed study titled “IL-17 Neutrophils in CF Lung Inflammation,” sponsored by University Hospitals Cleveland Medical Center. The registry lists cystic fibrosis as the condition, enrollment of 14, a start date of 2014-02, and primary completion of 2014-12.

The primary endpoint concerns change in the percentage of sputum neutrophils positive for IL-17 in the exacerbation cohort, measured at the beginning and end of intravenous antibiotic treatment. The record also describes interest in the relationship between the sputum measure and change in FEV1. It lists three outcome measures and zero analysis entries.

Numerical primary outcome findings, analysis methods, missing-data procedures, and multiplicity handling are not reported in the registry record. The stable cohort is not a like-for-like control for the primary endpoint, and the registry says stable-period sputum neutrophil studies were not undertaken. The recorded safety counts are zero affected in both listed groups, with different numbers at risk; deaths are recorded as null.