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 Pilot and Feasibility Study for the Treatment of Pre-diabetes in Patients With Cystic Fibrosis (NCT00763412), a randomized na study. The primary outcome is BMI.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00763412 |
| Phase | NA |
| Condition | Cystic Fibrosis Related Diabetes, Pancreatic Insufficiency |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 31 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Arbelaez, Ana Maria |
| Results posted | Yes |
2. Clinical Question
Population
Adolescents and young adults with cystic fibrosis and prediabetes were the intended population described in the study summary. The arm descriptions state that all participants had abnormal glucose tolerance. Pancreatic insufficiency is also listed among the conditions. The registry record does not report the age range, eligibility criteria in detail, or the primary-outcome analysis population.
Intervention
The active intervention was repaglinide, described as 0.5 mg before each meal, 3-4 times a day for 2 years. The study summary describes repaglinide as a medicine that increases insulin secretion from the pancreas. This description gives the study rationale; it does not establish an effect on the outcomes.
Comparator
The comparator was placebo. The arm description specifies 1 pill before each meal, 3-4 times a day for 2 years. Participants were randomized to placebo or drug. Further details about the placebo, treatment adherence, or any other care received are not reported in the registry record.
Primary question
The primary outcome was BMI, measured in Kg/m^2 at 2 year/end of study. The study summary describes a broader aim: to gather data and experience for planning a larger trial and to investigate whether repaglinide could affect nutritional status and pulmonary function through improved glucose control. The registry record does not report a formal primary hypothesis or an inferential comparison for BMI.
In statistical terms, the posted primary outcome asks what BMI values were recorded in each randomized arm at the stated endpoint. The reported arm summaries are a mean and a full range, each based on n=4. Those summaries describe the participants included in the posted outcome data; they do not by themselves establish whether any arm difference is compatible with chance, how precisely an arm contrast is estimated, or whether the finding applies beyond those participants.
3. Trial Design
This was a randomized, quadruple-masked, parallel-group study. The registry record lists the phase as NA and reports an enrollment of 31. The interventions were placebo and repaglinide. According to the arm descriptions, participants with abnormal glucose tolerance were randomized to one of these two groups. The record does not define the four parties covered by quadruple masking, describe how randomization was generated or concealed, or state whether masking was assessed.
The planned dosing descriptions specify a pill before each meal, 3-4 times a day for 2 years. For the repaglinide arm, the dose is listed as 0.5 mg. The placebo arm is described as receiving 1 pill. These registry descriptions do not establish whether participants followed the assigned schedule throughout the study. Adherence, treatment interruptions, and use of other therapies are not reported in the registry record.
The study is identified as a pilot and feasibility study. Its stated purpose was to gather data and experience needed to design a larger, full-scale trial. The summary also describes an interest in the relationship between systemic inflammatory factors and glucose impairment. The record does not report a formal feasibility criterion or a protocol-defined decision rule for proceeding to a larger study.
The recorded start was 2006-11, primary completion was 2013-01, and status is COMPLETED. These are registry dates and status, not a description of the duration of follow-up for every participant. The primary outcome timeframe is 2 year/end of study. Although overall enrollment was 31, the posted primary outcome summaries each have n=4. The registry record does not explain how these outcome counts relate to total enrollment or provide participant flow through randomization, follow-up, and 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
| Stage | Placebo | 2. Repaglinide |
|---|---|---|
| STARTED | 8 | 8 |
| COMPLETED | 4 | 4 |
| NOT COMPLETED | 4 | 4 |
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.
Population: Patients attended the Washington University CF Clinics between 2006 and 2008.
| Characteristic | Unit | Patients Who Received Placebo | Patients Who Received Repaglinide | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 4 | 8 | |
| Age, Categorical: <=18 years | Participants | 3 | 3 | 6 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 1 | 2 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 16 (12 to 18) | 15 (12 to 22) | 15.5 (12 to 22) |
| Sex: Female, Male: Female | Participants | 2 | 3 | 5 |
| Sex: Female, Male: Male | Participants | 2 | 1 | 3 |
| Region of Enrollment: United States | participants | 8 | 8 | 16 |
| BMI | Kg/m^2 | 19.45 (14.55 to 22.96) | 18.38 (16.78 to 20.3) | 18.94 (14.55 to 22.96) |
| Wt Z score | Z score | -1.11 (-1.84 to 0.33) | -0.29 (-0.75 to 0.19) | -0.7 (-1.84 to .33) |
| Fat % | % Fat mass | 20.34 (7.36 to 38.74) | 22.06 (9.76 to 28.81) | 21.2 (7.36 to 38.74) |
| Lean % | % Lean mass | 76.71 (58.6 to 89.67) | 75 (68.22 to 87.11) | 75.9 (58.6 to 89.67) |
| Tanner stage | units on a scale | 3.75 (2 to 5) | 3.25 (1 to 5) | 3.5 (1 to 5) |
| FEV 1 | % of lung function | 97.75 (92 to 121) | 92.75 (70 to 105) | 95.25 (70 to 121) |
| Fasting Glucose | mg/dl | 99.1 (87 to 114.5) | 100 (94 to 106) | 99.6 (87 to 114.5) |
| 2 hour glucose | mg/dl | 182.4 (144 to 218.5) | 183 (140 to 206) | 182.7 (140 to 218.5) |
| Fasting C-Peptide | mg/dl | 1.2 (0.6 to 2.1) | 1.7 (1.0 to 3) | 1.45 (0.6 to 3) |
| 2 hour c-peptide | mg/dl | 9.7 (6 to 15.5) | 9.5 (5 to 12.6) | 9.6 (5 to 15.5) |
6. Primary Endpoint
The registry lists the primary outcome as BMI, measured over 2 year/end of study.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | Kg/m^2 |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is BMI, reported in Kg/m^2, at 2 year/end of study. BMI is a measure derived from body weight in relation to height. In this trial, it serves as an indicator relevant to the study’s stated interest in nutritional status among adolescents and young adults with cystic fibrosis and abnormal glucose tolerance. The registry record identifies BMI as the primary measure but does not give a more detailed rationale for selecting it as the primary endpoint.
The posted outcome is summarized as a mean and full range within each arm. The placebo arm has a mean of 19.63, with a full range from 15.56 to 22.64; the repaglinide arm has a mean of 21.19, with a full range from 20.78 to 21.8. Each arm summary has n=4. The mean describes the average among the participants represented in that arm’s posted summary. The full range describes the lowest and highest reported values; it does not show how values are distributed between those endpoints.
These descriptive summaries do not provide an adjusted or unadjusted treatment-effect estimate, a confidence interval, or a p-value. The registry record does not specify whether the primary analysis was intended to compare endpoint BMI, change from baseline, or another quantity. Baseline BMI values and a primary-outcome analysis population are not reported in the registry record. Consequently, the endpoint summaries can be described as posted, but they do not support a complete assessment of change over time or the precision of an arm comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted BMI summaries are descriptive. At 2 year/end of study, the placebo arm has a reported mean of 19.63 and full range of 15.56 to 22.64; the repaglinide arm has a mean of 21.19 and full range of 20.78 to 21.8. Both summaries are based on n=4. These figures characterize the reported observations, not a tested treatment effect.
A mean and range alone cannot show whether an apparent difference between group averages is distinguishable from random variation. The record does not post a confidence interval or p-value for BMI, and no inferential analyses are reported. It also does not report baseline BMI by arm, so the endpoint summaries cannot establish whether the groups differed in BMI change from baseline. No adjusted analysis or model specification is reported in the registry record.
The full ranges indicate the observed span of values in each arm, but do not reveal individual values, distribution shape, or how sensitive each mean is to particular observations. With n=4 in each posted arm summary, the descriptive information is limited. This does not establish why the outcome counts are small relative to overall enrollment: the registry record does not explain the relationship between enrollment and the primary-outcome data. Missingness, exclusions, and the number randomized to each arm are not reported in the registry record.
The trial’s stated purpose was to inform the design of a larger study. The results posted for BMI therefore should be read as limited descriptive information from the recorded endpoint, rather than as a definitive estimate of an intervention effect. The registry record does not report a sample-size justification, a prespecified minimum important difference, or a criterion for interpreting the observed BMI values. It also does not report an analysis plan that would clarify whether these descriptive values were the intended primary analysis.
Other registered outcomes include glucose tolerance, inflammatory markers, weight Z score, Tanner stage, FEV 1, and C-peptide. Their presence indicates that the study covered more than BMI, but the record does not post their results in the registry record. No conclusions about those outcomes can be drawn from the BMI summaries. Overall, the posted primary-outcome data convey the arm-level mean and range among a small number of participants, while leaving the uncertainty and comparative interpretation unquantified.
9. Statistical Methods Explained
Descriptive statistics and comparison
The registry reports an arm-level mean and full range for BMI. The mean is a measure of the center of the observed values. The range gives the minimum and maximum, but does not describe the distribution between them. General statistical context: a treatment comparison ordinarily needs an estimate of the contrast between arms and a measure of its uncertainty. A confidence interval gives a range of values compatible with the data and the method’s assumptions; it is not a guarantee that the true effect lies within that interval. A p-value, when used, quantifies how surprising data at least as incompatible with a null hypothesis would be under that hypothesis and the analysis assumptions. Neither a confidence interval nor a p-value for BMI is reported in the registry record.
The posted summaries do not specify a model, baseline adjustment, or whether the intended comparison concerned endpoint values or change from baseline. Those choices matter because they define the quantity being estimated and can affect precision. Without a stated analysis method and an arm contrast, the means and ranges should remain descriptive rather than being interpreted as a formal efficacy comparison.
Randomization, masking, and parallel groups
The design is recorded as randomized and parallel, with quadruple masking. General statistical context: random allocation aims to make treatment groups comparable on average with respect to factors measured and unmeasured at entry. It does not ensure identical groups, especially in a small study. A parallel-group design assigns participants to one arm for the study comparison, rather than having each participant receive both interventions in sequence. Masking can reduce the influence of treatment knowledge on behavior, outcome assessment, and reporting, but the registry record does not explain who was masked or how masking was maintained. Randomization methods, allocation concealment, and masking procedures are not reported in the registry record.
Precision and small outcome counts
Each posted primary-outcome arm summary includes n=4. General statistical context: estimates from small groups can be imprecise, and a mean may be sensitive to individual observations. A range can make the spread of the observed endpoints visible, but does not replace an uncertainty interval for a comparative effect. The full range is especially limited as a description of distribution: it does not show clustering, asymmetry, or the values between the endpoints. The registry record does not report a confidence interval, standard error, or other uncertainty measure for the arm means or their contrast.
The overall enrollment is 31, but the record does not explain why the posted primary-outcome counts are n=4 in each arm. It would be inappropriate to treat the difference between overall enrollment and these outcome counts as a particular type of missingness or withdrawal without participant-flow information. The relationship between enrollment and analyzed participants, along with reasons for any absent outcome data, is not reported in the registry record.
Planning assumptions
The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For time-to-event planning, the record says the total number of events is used; for other outcomes, it says participants per arm. These are planning illustrations, not observed power, and they are not a report of the trial’s own design justification. No sample-size justification for this trial is reported in the registry record. A planning result based on an observed effect should not be interpreted as evidence that the trial had a particular probability of finding a true effect.
General statistical context: power is a design concept tied to a specified effect, variability, analysis, and significance threshold. It is not a measure of whether the observed result is true. A calculation that uses an effect estimated from a small study can be unstable, because that effect estimate itself may be imprecise. No numerical planning sample sizes or effect fractions are stated in the registry record details described for this analysis, so no such values can be interpreted.
Distributional assumptions
General statistical context: methods based on a normal approximation rely on assumptions about how the estimate behaves, often becoming more credible with adequate information and a suitable model. An outcome with more variation than a model anticipates is described as over-dispersed. Over-dispersion can make standard errors too small and confidence intervals too narrow if the model fails to account for it. This study’s posted BMI summaries do not establish whether a normal model is appropriate, and the registry record does not identify a distributional model for the primary endpoint. The normal approximation mentioned for planning is not by itself evidence that a normal model was used to analyze the observed BMI data.
Analysis and recalculation
No inferential analyses are reported in the registry record for the primary BMI outcome. There is therefore no sponsor-reported contrast or test statistic to set alongside a recalculated comparison. The registry record also does not state whether any primary analysis was adjusted for baseline values or other covariates. No adjusted estimate should be inferred from the arm summaries. Any simple re-calculation from posted summary statistics, if presented elsewhere, would be an unadjusted calculation and would not substitute for a prespecified sponsor analysis. The registry record does not provide enough information in the registry record to assess a model-based estimate or its assumptions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six secondary outcomes: glucose tolerance, inflammatory markers, Wt Z Score, Tanner Stage, FEV 1, and C-Peptide. It also reports nine outcome measures overall. The record does not clarify how the named outcomes correspond to that total, which outcomes were formally designated as secondary, or whether additional outcome measures were included. A statistical plan for controlling the chance of false-positive findings across multiple outcomes is not reported in the registry record. No secondary outcome analyses are reported in the registry record for this analysis.
General statistical context: when many hypotheses are tested, the chance of at least one apparently noteworthy result can increase if each is judged separately. Prespecified outcome hierarchies or multiplicity-adjustment methods can address that issue, but the registry record does not describe whether either approach was planned. The absence of a reported plan does not establish which approach was used in practice.
Missing-data methods and reasons for missing outcome values are not reported in the registry record. The record gives overall enrollment of 31 and posted primary BMI summaries with n=4 in each arm, but does not explain the participant flow or the relationship between these counts. It does not report the number randomized per arm, the number completing follow-up, exclusions from analysis, or a method for handling unavailable BMI measurements.
The analysis population is not reported in the registry record. It is therefore not possible to determine from these registry entries whether the posted summaries represent all randomized participants with available measurements, a per-protocol group, or another population. Baseline characteristics by arm and a prespecified missing-data strategy are also not reported. These gaps limit assessment of how representative the endpoint summaries are of the randomized groups.
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 |
|---|---|---|---|
| Placebo | 0 | 8 | 0.0% |
| Repaglinide | 0 | 8 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Placebo | 0 of 8 |
| Repaglinide | 0 of 8 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo | 0 of 8 |
| Repaglinide | 0 of 8 |
The registry reports serious adverse event figures for placebo and repaglinide. In each arm, 8 participants are listed as at risk for serious events, and 0 as affected. The record also lists 8 participants at risk for other adverse events in each arm and 0 as affected. Deaths are listed as 0 in each arm, and no top serious-event terms are listed.
These are the posted counts, not a complete description of the safety experience. The registry record does not provide event-level narratives, follow-up time for safety, severity grading beyond the serious-event classification, or details about how events were collected and adjudicated. The number at risk in these safety summaries should not be assumed to represent the full randomized sample, because the record does not explain the relationship between these counts and overall enrollment.
General statistical context: observing zero events in a group does not prove that the underlying risk is zero. The precision of safety estimates depends on the amount of information and the duration and completeness of observation. With no comparative analysis or uncertainty estimate reported, these counts alone do not establish that the arms have equivalent safety profiles. They describe only the adverse-event figures recorded in the registry.
12. What the Result Does, and Does Not, Mean
The posted BMI results give a descriptive snapshot of the participants included in the primary-outcome summaries. At 2 year/end of study, the placebo mean is 19.63, with a full range of 15.56 to 22.64; the repaglinide mean is 21.19, with a full range of 20.78 to 21.8. Each arm summary is based on n=4. These figures show the recorded values in each arm summary, but do not quantify uncertainty around the comparison.
They do not establish whether repaglinide changed BMI relative to placebo. The registry record does not report a between-arm estimate, confidence interval, p-value, or primary analysis method. It also does not post baseline BMI by arm, so the endpoint means cannot be used to describe change from baseline. No conclusion about nutritional status beyond these BMI summaries is established by the posted data.
The trial was described as a pilot and feasibility study intended to inform the design of a larger trial. This purpose is important when interpreting the limited outcome reporting: the available primary-outcome summaries are descriptive, while the information needed for a precise comparative assessment is not reported. The record does not state a minimum important BMI difference or a threshold for success.
The posted safety counts list zero affected participants for the serious and other adverse-event categories in both arms, with 8 at risk in each arm for each category. Those counts do not prove that no risk exists or establish equivalent safety. The record does not give enough detail to assess the completeness and duration of event observation.
The study summary mentions pulmonary function, glucose control, and inflammatory factors, and the registry lists secondary outcomes related to these topics. Their results are not reported in the registry record used for this analysis. The BMI summaries cannot establish findings for those outcomes or the proposed relationships among glucose impairment, inflammation, nutrition, and pulmonary function. Overall, the posted record supports a narrow description of the endpoint and safety counts; it does not support a definitive treatment-effect conclusion.
13. Why This Trial Matters Statistically
This study illustrates a recurring statistical distinction: a trial can have a randomized design while its posted results remain descriptive and limited. Randomization is relevant to how treatment groups are formed, but interpretation still depends on the outcome data, analysis population, and uncertainty around the comparison. Here, the registry reports arm-level BMI means and ranges based on n=4 in each arm, without an inferential comparison. That combination makes it important not to treat the numerical summaries as a definitive estimate of a treatment effect.
The pilot and feasibility purpose also matters. The study summary explicitly describes an aim of gathering data and experience for designing a larger trial. Pilot studies can inform later research, but the registry record does not report formal feasibility targets, a progression criterion, or a sample-size justification. The planning assumptions described in the record are illustrations, not evidence of the rationale used to design this trial and not observed power.
The difference between overall enrollment of 31 and the n=4 primary-outcome summaries underscores the value of transparent participant flow. Without an explanation of these counts, readers cannot determine from the record whether the outcome summaries represent a restricted analysis population, incomplete outcome reporting, or another circumstance. The reason is not reported in the registry record.
The record also highlights the need to distinguish a registered outcome from a reported analysis. BMI is named as primary, while several secondary outcomes are listed, but a statistical analysis plan, multiplicity approach, and missing-data method are not reported. Clear reporting of these details would help readers evaluate what was intended, what data contributed, and how much uncertainty surrounds any comparison. In their absence, a careful reading stays close to the arm-level numbers and does not infer results for unreported outcomes.
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 primary BMI summaries are based on n=4 in each arm, while overall enrollment is 31. The registry record does not explain the relationship between these counts. This limits interpretation of how many participants contributed to the endpoint summaries and whether they represent the randomized groups. Participant flow, reasons for unavailable measurements, and exclusions are not reported in the registry record.
The record reports means and full ranges, but not individual BMI values, standard deviations, standard errors, confidence intervals, or a between-arm estimate. It does not report baseline BMI by arm, an analysis of change, or an adjusted analysis. Consequently, the extent and precision of any treatment contrast cannot be evaluated from these summaries alone.
The analysis population, missing-data handling, and statistical model are not reported in the registry record. Nor are randomization procedures, allocation concealment, details of quadruple masking, adherence, or treatment discontinuation. The record does not provide a sample-size justification, interim analysis plan, or primary hypothesis. These omissions prevent a full assessment of the planned analysis and conduct.
The record lists secondary outcomes but does not report their results in the registry record used for this analysis. It does not explain how the listed outcomes correspond to the reported total of nine outcome measures or identify a multiplicity strategy. Safety counts are also limited: the record lists at-risk and affected counts but does not detail observation time or event ascertainment. These are limitations of the information reported in the registry record and should not be taken as proof that particular procedures or analyses were not performed.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pilot and Feasibility Study for the Treatment of Pre-diabetes in Patients With Cystic Fibrosis — NCT00763412.
- Registry record last updated 2017-06-05; status last verified 2017-05.
- Results first posted 2017-06-05.
- 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
The registry record identifies a completed randomized, quadruple-masked, parallel-group pilot and feasibility study comparing placebo with repaglinide in adolescents and young adults with cystic fibrosis and abnormal glucose tolerance. Enrollment is 31. The listed primary outcome is BMI in Kg/m^2 at 2 year/end of study.
The posted BMI summaries are a mean of 19.63 and full range of 15.56 to 22.64 for placebo, and a mean of 21.19 and full range of 20.78 to 21.8 for repaglinide. Each arm summary has n=4. No inferential analysis of BMI is reported in the registry record. Serious and other adverse-event counts list 0 affected participants in each arm, with 8 at risk per arm for each category; deaths are listed as 0.
The study summary describes a goal of informing the design of a larger trial and investigating glucose impairment and inflammatory factors. Statistical analysis details, participant flow, and the relationship between total enrollment and posted primary-outcome counts are not reported in the registry record.