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 An Efficacy and Safety Study of Ivacaftor in Patients With Cystic Fibrosis and Two Splicing Mutations (NCT02934698), a na phase 3 study. The primary outcome is Forced Expiratory Volume.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02934698 |
| Phase | Phase 3 |
| Condition | Cystic Fibrosis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 2 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Medical University of South Carolina |
| Results posted | Yes |
2. Clinical Question
Population
Two sisters with cystic fibrosis, two splicing mutations, and pancreatic sufficiency.
Intervention
Open-label ivacaftor treatment for 6 months.
Comparator
There is no separate comparator group. Both participants are assigned to the single ivacaftor arm.
Primary question
What is the absolute change in forced expiratory volume in 1 second, expressed as a percentage of predicted, from baseline through week 24?
The registry describes a postmarketing study intended to evaluate efficacy and safety in a highly specific population: two sisters with cystic fibrosis and two splicing mutations. The intervention is open-label ivacaftor, and the record describes both participants receiving treatment for 6 months. The primary endpoint concerns change in FEV1, a measure of lung function, expressed relative to a predicted value. The stated assessment period is from baseline through week 24.
This is a descriptive question about the participants' changes during treatment, not a randomized comparison of ivacaftor with another treatment or with no treatment. Because there is no control group, the study cannot separate changes occurring during treatment from changes that might have occurred over the same period for other reasons. The registry record does not report numerical FEV1 results, so the direction or size of the participants' changes cannot be described from the record.
The record also lists sputum results and sweat chloride as secondary outcomes. It does not report numerical results for those outcomes. The clinical question is therefore clear as a planned evaluation, but the posted record does not provide the outcome data needed to characterize what was observed.
3. Trial Design
The registry classifies this study as Phase 3 and as a single-group study. It lists an enrollment of 2 and describes the participants as two sisters with cystic fibrosis and pancreatic sufficiency. The sponsor is the Medical University of South Carolina. The study began on 2016-11-01, had a primary completion date of 2018-05, and is marked completed.
Ivacaftor is the only listed intervention. The arm description says both participants received ivacaftor for 6 months. Masking is listed as none, consistent with an open-label design in which treatment assignment is not masked. Allocation is listed as not applicable, and the record does not identify a second arm or a control treatment.
The primary outcome is forced expiratory volume in 1 second, measured as a percentage of predicted. The stated endpoint is the absolute change from baseline through week 24. Sputum results and sweat chloride are listed as secondary outcomes. The record indicates three outcome measures overall, but does not provide analysis results for them.
This design supports a description of outcomes in the two treated participants. It does not provide a like-for-like control comparison, and the registry record itself flags that the study is not a randomized comparison. Allocation, a randomized sequence, and a comparator arm are not reported as applicable. The statistical analysis plan, including any planned summary method beyond the endpoint's stated mean parameter, is not reported in the registry record.
The registry describes the study as postmarketing and says it was designed to evaluate efficacy and safety. Further details about the protocol, eligibility criteria beyond the described population, treatment adherence, or any changes to the study plan 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
| Stage | Ivacaftor |
|---|---|
| STARTED | 2 |
| COMPLETED | 2 |
| NOT COMPLETED | 0 |
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.
| Characteristic | Unit | Ivacaftor |
|---|---|---|
| Participants analysed | 2 | |
| Age, Continuous | years | 37 (36 to 38) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 2 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 2 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Forced Expiratory Volume, measured over 24 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | percentage of predicted |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the absolute change in FEV1 from baseline through week 24, expressed as a percentage of predicted. FEV1 is the volume of air exhaled in the first second of a forced breath. Expressing the measure as a percentage of predicted places a participant's measured lung function in relation to a predicted reference value. The endpoint focuses on change over the stated assessment period rather than on a single follow-up measurement alone.
Change from baseline is commonly used to describe how a measurement differs over time within participants. In a single-group study, that change is a within-participant description; it is not, by itself, an estimate of the difference between treatment and control. General statistical context: a comparison group can help distinguish a treatment-associated change from changes that may reflect time, measurement variation, or other influences. There is no separate comparator arm in this study.
The registry lists the endpoint parameter as a mean and the dispersion as the full range. A mean describes the average of the measured values, while a full range describes their spread from the lowest to the highest value. With only two participants, individual observations are especially important for understanding any group summary. However, the registry record does not report the mean change, the full range, individual results, or a confidence interval. It therefore does not allow readers to assess either the magnitude or precision of the endpoint estimate.
The endpoint's timeframe is 24 weeks, while the arm description specifies treatment for 6 months. The record does not provide further detail about the timing of measurements within that interval or the handling of measurements that may be missing.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed, open-label study of ivacaftor in two participants, with FEV1 change through week 24 as the primary endpoint. It does not report a numerical FEV1 result or an analysis for that endpoint. As a result, no direction, magnitude, or precision of change can be stated from the record. The record also does not provide numerical results for the listed secondary outcomes, sputum results and sweat chloride.
The design places important limits on interpretation. Both participants received the intervention, and no separate comparator group is listed. Any observed change over time in a single-group study is descriptive. It cannot establish how the same participants would have changed over the same period without ivacaftor, or under a different treatment. The open-label design also means masking was absent; the record does not explain whether this could have affected measurement or reporting.
The enrollment of 2 makes the study an account of two individuals rather than a basis for estimating outcomes reliably across a broad population. General statistical context: estimates based on very few observations are sensitive to each participant's result, and uncertainty is difficult to characterize precisely. The registry does not report a confidence interval, individual participant values, or a statistical test for the primary endpoint.
The record identifies a mean as the endpoint parameter and the full range as the dispersion measure, but those summaries are not reported numerically. A mean alone would not show whether the participants had similar or different changes; the full range can convey spread, but with only two participants it would remain a limited description of variability. The posted results also contain no analysis records.
The safety information records no participants with serious adverse events and no deaths, while both participants are recorded as having other adverse events. These are counts from a very small group and do not establish the frequency or nature of harms in a wider population. The registry does not list the terms for serious adverse events or provide details of the other adverse events.
The registry includes planning assumptions for sample-size illustrations, but those assumptions do not supply missing outcome results or turn the study into a comparative trial. They describe a hypothetical planning exercise using equal allocation between two arms, whereas this study has one group. Any planning illustration is not observed power and should not be read as evidence about the treatment effect in these participants.
9. Statistical Methods Explained
What does a single-group design estimate?
This study has one treatment group and no separate comparator. Its stated primary endpoint is the change in FEV1 from baseline through week 24. In general, a within-group change describes how measurements differ over time among participants who received the intervention. It does not estimate the contrast between outcomes under treatment and outcomes under an alternative condition. Without a control group, changes related to time, natural variation, measurement conditions, or other influences cannot be separated from changes associated with treatment.
This distinction matters when describing results. A change recorded during treatment is not equivalent to a controlled treatment effect. The registry record flags the absence of a randomized comparison and notes that the arms are not a like-for-like control comparison. There is no second arm described in the study design.
What does the endpoint summary mean?
The endpoint is specified as a mean, with the full range as its dispersion. In general, the mean is an average that gives a compact description of a set of observations. The full range describes the span between the lowest and highest observations. These summaries answer different questions: the mean describes a central value, while the range gives some information about how much observations vary. Neither summary is reported numerically in the registry record.
With only two participants, a group summary cannot show the diversity of outcomes in a larger population. Each participant's value would be important to understanding the mean and range. The record does not provide those individual values, so readers cannot check whether the participants had similar changes or whether one result was markedly different from the other. A confidence interval, which in general describes uncertainty around an estimate under specified assumptions, is not reported either.
What role would a statistical test play?
A statistical test can assess how compatible observed data are with a specified statistical hypothesis under a model. Its interpretation depends on the hypothesis, analysis method, and assumptions. The registry lists no analyses, and statistical tests or p-values for the primary endpoint are not reported in the registry record. It would therefore be inappropriate to infer a test result or significance from the design or from the enrollment alone.
General statistical context: a p-value does not measure the size or importance of an effect, and it does not establish that a result is causal. Effect estimates and measures of uncertainty are needed to describe magnitude and precision. For this study, neither numerical endpoint estimates nor uncertainty intervals are reported.
How should the sample-size illustration be understood?
The registry's planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The assumptions also describe planning for stated fractions of an observed effect. These are planning conditions, not a description of the study's actual single-group design. The registry record does not report a sample-size justification for the study itself.
A sample-size illustration asks what enrollment could be required under specified assumptions for a hypothetical comparison. It is not a measure of the probability that a completed study found an effect. In particular, it is not observed power. Because the actual study has one group and enrollment of 2, assumptions based on equal allocation between two arms do not describe its design. The registry does not report the effect estimate underlying the illustration in the outcome results, so the numerical implications cannot be evaluated from the record alone.
Why does dispersion matter?
General statistical context: dispersion describes variation among observations. When observations vary more than a model assumes, standard errors and confidence intervals based on that model may not represent uncertainty well. This issue is often called over-dispersion in settings where a model expects less variation than appears in the data. The registry record does not report a model for the primary outcome or evidence of over-dispersion, so this is a general consideration rather than a finding about this study.
The endpoint specifies the full range as its dispersion summary, but the range is not posted numerically. No model-based uncertainty estimate is reported. Consequently, neither the amount of observed variation nor the suitability of a particular statistical model can be assessed from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies FEV1 change as the primary outcome and lists sputum results and sweat chloride as secondary outcomes. It indicates three outcome measures overall. No analysis results are listed, and the record does not provide numerical estimates for any of these outcomes.
When a study examines multiple outcomes or performs multiple statistical tests, the chance of finding at least one apparently unusual result can increase. General statistical context: multiplicity methods are sometimes used to control or describe that issue, depending on the study's aims and analysis plan. Whether the investigators planned adjustments, a hierarchy among outcomes, or other multiplicity procedures is not reported in the registry record. No testing results are available to interpret in light of such choices.
The record does not describe missing-data methods, the amount or reasons for missing outcome measurements, or whether all participants contributed data at each assessment. It does not identify an analysis population, such as a population defined by treatment received or by protocol adherence. The population field for the primary outcome is blank. No imputation approach, sensitivity analysis, or rule for handling incomplete follow-up is reported in the registry record.
These omissions mean the registry does not allow an assessment of whether missing observations or analytic choices affected the reported estimates. Since no estimates are reported, the scope of any such effects cannot be quantified. The absence of information is not evidence that missing data or multiplicity adjustments were handled in a particular way.
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 |
|---|---|---|---|
| Ivacaftor | 0 | 2 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Ivacaftor | 0 of 2 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Ivacaftor | 2 of 2 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Ivacaftor |
|---|---|---|
| Sinus congestion | Infections and infestations | 2 of 2 |
| Folliculitis | Skin and subcutaneous tissue disorders | 1 of 2 |
| palpitations | Cardiac disorders | 1 of 2 |
The safety record lists 2 participants at risk in the ivacaftor group. It records 0 participants with serious adverse events and 0 deaths. It also records 2 participants with other adverse events. The record does not list terms for serious adverse events.
These categories should be kept distinct. The serious adverse event figure concerns participants recorded as affected, while the other adverse event figure refers to a separate category in the registry. The record does not provide details of the types, severity, timing, or duration of the other adverse events. It also does not report whether any event led to treatment interruption or discontinuation.
General statistical context: a count from a very small group describes only the participants observed; it cannot characterize uncommon events or establish a reliable rate in a broader population. The absence of recorded serious adverse events or deaths in this group does not establish that such events cannot occur. Because the study has no comparator group, the safety figures also do not show how event occurrence compares with another treatment or with no treatment.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed, open-label, single-group study evaluated ivacaftor in two sisters with cystic fibrosis, two splicing mutations, and pancreatic sufficiency. It identifies FEV1 change through week 24 as the primary endpoint and lists sputum results and sweat chloride as secondary outcomes. The safety record reports no participants with serious adverse events, no deaths, and two participants with other adverse events.
Those details describe the study's design and the posted safety counts. They do not establish the magnitude or direction of change in FEV1, because the registry record does not report numerical results for the primary endpoint. Nor does it provide numerical results for the secondary outcomes. Without estimates and measures of uncertainty, the precision of any outcome change cannot be assessed.
The single-group design also does not support a controlled comparison. Even if a change were reported, a before-and-after observation in treated participants would not by itself distinguish treatment-associated change from changes that could occur over time or for other reasons. The absence of masking is another design feature to consider, but the record does not report its consequences for measurement or reporting.
The study's enrollment of 2 supports a narrow description of the two participants, not a reliable estimate for a wider population. The registry does not report individual outcome values, a confidence interval, or statistical tests. It also does not provide enough information to assess missing data or the analysis population. Accordingly, neither the size of any effect nor its uncertainty can be characterized from the posted results.
These limitations do not negate the descriptive value of a study in a specific population. They define what can and cannot be concluded from the registry record: the design and safety counts are available, but numerical efficacy outcomes and comparative evidence are not reported.
13. Why This Trial Matters Statistically
This study is statistically notable for its narrow population and very small enrollment: it describes two sisters with cystic fibrosis and two splicing mutations. Such a study can document an investigation in a specific clinical context that may not be well represented by larger, broader studies. Its value as a description of those participants should be distinguished from its ability to estimate outcomes for other people.
The design also makes the interpretation especially dependent on recognizing the difference between within-person change and a treatment comparison. Both participants received open-label ivacaftor, and no control group is described. A change from baseline, if reported, would be informative as an observation over time, but could not by itself isolate the effect of treatment from other influences.
Another statistical lesson is the importance of reporting estimates and their uncertainty. The record identifies the primary endpoint and its summary approach, but does not report numerical FEV1 results, individual values, or confidence intervals. Without them, readers cannot judge the magnitude, variability, or precision of the outcome. The posted safety counts are also descriptive and apply only to the small group recorded.
The registry's sample-size assumptions illustrate why planning calculations need to match the design and question being studied. The stated illustration assumes equal allocation between two arms, while the actual study is single-group. Such planning assumptions are not a substitute for observed results and do not convey observed power. The study therefore offers a useful example of how design, population size, comparator availability, and complete outcome reporting shape the conclusions that statistical evidence can support.
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 principal limitation is the absence of numerical outcome results in the registry record. Although FEV1 change is named as the primary endpoint and sputum results and sweat chloride are listed as secondary outcomes, no estimates or analyses are reported. The record therefore does not permit a statistical assessment of efficacy outcomes.
Enrollment was 2, and the participants are described as two sisters. The findings, even if numerical results were available, would be limited in their ability to represent people beyond this specific pair. Shared family characteristics may also mean the participants do not provide the range of variation that would be expected in a broader group; the registry does not provide information to assess this further.
The study is open-label and has no separate comparator group. Thus, any within-participant changes could not be interpreted as a controlled treatment effect. The record does not report individual measurements, outcome uncertainty, statistical tests, missing-data handling, analysis populations, or details of multiplicity procedures. These gaps prevent evaluation of the robustness and precision of any outcome estimates.
For safety, the record provides counts but no event terms for serious adverse events and no details of the other adverse events. The small group and lack of a comparator limit conclusions about the frequency or attribution of events. Further information about adherence, protocol deviations, and measurement timing is not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: An Efficacy and Safety Study of Ivacaftor in Patients With Cystic Fibrosis and Two Splicing Mutations — NCT02934698.
- Registry record last updated 2018-08-06; status last verified 2018-07.
- Results first posted 2018-08-06.
- 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
NCT02934698 is a completed Phase 3, open-label, single-group study sponsored by the Medical University of South Carolina. It enrolled 2 participants: two sisters with cystic fibrosis, two splicing mutations, and pancreatic sufficiency. Both received ivacaftor for 6 months.
The primary outcome is absolute change in FEV1, expressed as a percentage of predicted, from baseline through week 24. Sputum results and sweat chloride are listed as secondary outcomes. The registry record does not report numerical outcome results or analyses.
The safety record lists 0 participants with serious adverse events, 2 with other adverse events, and 0 deaths. The design has no control group, and the posted record does not provide enough outcome detail to assess efficacy estimates or their precision.