Nitrite Infusion in Islet Cell Transplantation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nitrite Infusion in Islet Cell Transplantation (NCT03544242), a randomized phase 2 study. The primary outcome is Prior to Infusion Blood Glucose Serum Levels.

2. Clinical Question

In statistical terms, the intended question concerns measurements made around a specific point in the islet-cell transplantation process, in a randomized, parallel-group study. The available record is not sufficient to establish how the glucose measurements were summarized or whether the primary question was framed as a difference between particular arms, a change over time, or another contrast. The registry explicitly says the study did not reach sufficient enrollment power for statistical analysis. It also records no analyses. Consequently, the trial record does not provide an estimate of the size or precision of any treatment-group difference. The intervention labels indicate timing around isolation, but do not by themselves establish the exact procedures or comparisons used in practice.

3. Trial Design

NCT03544242, titled “Nitrite Infusion in Islet Cell Transplantation,” is recorded as a phase 2, randomized, double-masked, parallel-group trial sponsored by the University of Alabama at Birmingham. The registry lists enrollment of four and status as terminated. The record gives a start date of 2017-05-07 and a primary completion date of 2019-06-27. It does not state why the trial was terminated.

The listed arms are Control, Pre-Isolation Infusion, and Post-Isolation Infusion. The brief summary describes the investigation of nitrite administration to pancreatic islet cells removed from a patient for autotransplantation. The primary outcome timeframe refers to the interval between induction and the time immediately before infusion of either nitrite or saline. Beyond these labels and descriptions, the registry does not report the detailed treatment procedures, the allocation ratio, or how the masking was implemented. The descriptions for the arms are blank, so the exact contents of each arm are not specified in the registry record.

Randomization is a design method intended to make assigned groups comparable, on average, with respect to measured and unmeasured factors. Masking is intended to limit the influence of treatment knowledge on care, measurement, and interpretation. These are general purposes of the design features; the registry does not provide enough detail to assess their execution in this trial. A parallel design assigns participants to groups that remain separate rather than crossing participants between treatments, but the record does not describe the treatment schedule or follow-up in sufficient detail to characterize it further.

The recorded enrollment is very limited, and the registry states that enrollment was insufficient for statistical analysis. Thus, the design labels describe how the trial was intended to be organized, not a basis for drawing a reliable treatment comparison from the posted results. The registry does not report a sample-size justification, recruitment targets, reasons for stopping, or protocol deviations.

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: The study did not reach sufficient enrollment power for statistical analysis.

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 Prior to Infusion Blood Glucose Serum Levels, measured over Between the time of induction and the time immediately prior to infusion of either nitrite or saline.

The primary outcome is titled “Prior to Infusion Blood Glucose Serum Levels.” It concerns blood serum glucose measured from a blood sample collected between induction and immediately before infusion of either nitrite or saline. The record describes a sample amount of 3-5 cc. This endpoint therefore captures glucose at a specified procedural time, rather than reporting a later clinical outcome.

As a general statistical matter, defining an endpoint and its measurement time before examining results helps make clear what quantity a study is intended to assess. A measurement close to an intervention can describe the state of the measured variable at that point, but interpretation depends on the planned comparison, the measurement scale, and the analysis method. The registry gives no unit, summary statistic, threshold, or numerical glucose result. It also does not state whether the intended analysis used a single measurement, repeated measurements, or a change from another time point.

The study summary concerns nitrite administration in the context of islet-cell autotransplantation, while the named primary endpoint is a blood measurement before infusion. The registry does not explain how that measurement was expected to relate to a later outcome or to a proposed biological mechanism. Such a rationale is not reported in the registry record. The record says the study did not reach sufficient enrollment power for statistical analysis, and it contains no reported analysis of this endpoint. Accordingly, the endpoint can be described, but its result and any between-group contrast cannot be interpreted from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies randomization, double masking, and a parallel model, but it does not report a statistical analysis plan or any completed analyses. The explanations below describe general statistical principles and distinguish them from methods documented for this trial. No particular test or model can be attributed to the trial unless the registry record states it.

What does randomization contribute?

General: random assignment is intended to reduce systematic differences between treatment groups at the point of allocation. It does not guarantee identical groups, especially when enrollment is limited. It also does not correct problems that arise after assignment, such as incomplete outcome measurement, departures from the assigned procedure, or selective reporting. The registry does not describe the random sequence, allocation concealment, or the process used to assign participants. Therefore, the design label alone does not allow assessment of those implementation details.

Double masking is also listed. General: masking can reduce the chance that knowledge of assignment affects participant experience, clinical management, outcome measurement, or interpretation. The registry does not say who was masked, how masking was maintained, or whether it was assessed. The term should therefore be read as a reported design characteristic, not as evidence that masking was successful throughout the trial.

What can be inferred from the endpoint description?

The primary outcome concerns serum glucose measured before infusion, with a timeframe between induction and immediately prior to infusion of nitrite or saline. The registry describes a blood sample of 3-5 cc. It does not state the units, planned summary measure, target contrast, handling of repeated measurements, or a model for analysis. General: a statistical analysis needs a clear definition of the outcome, the comparison of interest, and the participants or observations included. The endpoint title and timeframe identify some of that structure, but not enough to reconstruct a complete analysis.

The record notes that the primary outcome has several categories or time points and was not reduced to one comparison. That matters because an outcome with multiple components or measurement times can support multiple possible contrasts. The choice among those contrasts affects the statistical question. Without a prespecified primary contrast and the corresponding results, there is no single effect estimate to summarize from the registry record.

Why do estimates need uncertainty measures?

General: an estimate is a numerical summary of the data under a chosen method. A confidence interval is a range generated by a procedure that, under its assumptions, has a stated long-run coverage property. It conveys precision and the range of values reasonably compatible with the observed data and method. A narrow interval generally reflects greater precision than a wide interval, but an interval is not a guarantee that the true value lies inside it. No estimate or confidence interval for the primary outcome is reported, so precision cannot be assessed.

A p-value, when available, measures how unusual data at least as inconsistent with a specified null hypothesis would be under that hypothesis and the test assumptions. It is not the probability that the null hypothesis is true, and it does not express the size or importance of an effect. The registry reports no analysis and no p-value for the primary endpoint. Accordingly, there is no basis to characterize the primary comparison as statistically significant or nonsignificant.

What do planning calculations mean?

General: sample-size planning asks how many observations a future or ongoing study may need under chosen assumptions about the effect to detect, variability, allocation, significance level, and desired power. A planning illustration based on an observed effect is not the trial's original sample-size justification. It is also not observed power, which is not a useful substitute for reporting an estimate and its uncertainty after data collection. The planning assumptions described for this analysis specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is described as a stated fraction of an observed effect. These assumptions do not establish that the trial itself was designed using them.

The primary outcome is not reduced to one comparison in the registry-derived analysis, and no primary estimate is reported in the registry record. Therefore, a planning illustration tied to an observed effect cannot supply a missing clinical result. Any planning figure should be read as conditional on the stated assumptions, not as a summary of what happened in the trial or evidence that the trial had adequate power.

How should multiple outcomes be considered?

General: when a study examines multiple outcomes, time points, or comparisons, the chance of at least one false positive can increase if each is tested independently without an appropriate plan. Prespecifying a primary outcome and analysis, or using a justified adjustment strategy, can help clarify interpretation. The registry lists eight outcome measures but reports no analyses and does not state how multiplicity was handled. It does not report whether any adjustment was planned, or which outcome contrasts were considered confirmatory. No multiplicity procedure should be assumed.

These principles explain what a complete statistical report can address; they do not fill gaps in the record. For this study, the registry does not report an analysis plan, a model, estimates, uncertainty intervals, or hypothesis-test results. The reported design and endpoint information is not enough to recreate those missing analyses.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures and reports zero analyses. It does not report a multiplicity strategy, such as a hierarchy of outcomes, a prespecified primary contrast, or an adjustment for testing several outcomes or time points. The primary outcome record itself indicates that there are several categories or time points and that it was not reduced to one comparison. As a result, the registry does not identify a single analyzed primary contrast or describe how any multiple comparisons would have been interpreted.

General: multiplicity matters when more than one statistical question is examined. If each question is tested separately, the chance of finding at least one apparently unusual result can be greater than for a single planned test. Methods for addressing this include prespecifying a primary question, controlling error across a family of tests, or treating secondary results as exploratory. Which approach is appropriate depends on the design and scientific objectives. None is documented for this trial, so readers should not assume one was used.

The analysis population is not reported in the registry record. The record does not specify whether an intention-to-treat, per-protocol, or other population was planned, nor how participants with missing measurements or protocol deviations would be handled. Missing-data methods, the amount of missing outcome data, and reasons for missingness are also not reported. The enrollment of four and the statement that the study did not reach sufficient enrollment power for statistical analysis do not establish whether measurements were complete for every participant. In the absence of analysis populations, missingness information, and an analysis plan, the primary endpoint cannot be reconstructed or evaluated for potential selection effects.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports serious adverse-event counts separately for Control, Pre-Isolation Infusion, and Post-Isolation Infusion. The numbers at risk are 1, 1, and 2, respectively; the number affected by a serious adverse event is 0 in each group. Deaths are recorded as 0 in each group. For other adverse events, the numbers at risk are likewise 1, 1, and 2, and the number affected is 0 in each group. No serious adverse-event terms are listed.

These are event counts, not estimates of comparative risk. General: a count of zero means that no event was recorded in the stated group and registry category; it does not demonstrate that the underlying event risk is zero. With enrollment this limited, the counts provide little information about uncommon events or differences between groups. The registry does not report the duration of safety follow-up, the method of event collection, or whether all participants completed the same observation period. Those omissions limit interpretation of the zero counts. The record supports describing what was recorded, but not concluding that one treatment assignment is safer than another.

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

The trial record documents an investigation of nitrite infusion in the setting of islet-cell autotransplantation. It identifies randomized, double-masked, parallel-group design features and names blood glucose serum levels before infusion as the primary outcome. It also records four participants, termination, and no statistical analyses. These registry entries describe the study and its reporting status; they do not establish a treatment effect.

The registry says that the study did not reach sufficient enrollment power for statistical analysis. It does not provide a primary-endpoint estimate, a comparison between groups, a confidence interval, or a hypothesis-test result. Consequently, the posted results do not show whether glucose levels differed by assigned group, nor do they indicate the size or precision of any difference. Lack of a reported comparison should not be read as a finding of no difference. It is an absence of evidence from a completed statistical analysis in the registry record.

General: a randomized trial can provide a useful comparative estimate when the outcomes, analysis population, and contrasts are defined and the results are reported with appropriate uncertainty. Randomization alone does not guarantee a precise estimate, and masking does not replace outcome data. When enrollment is limited and no analysis is reported, design features cannot compensate for the missing comparison. In this record, the stated design is not accompanied by enough outcome information to judge the primary question.

The safety counts show no recorded serious adverse events, other adverse events, or deaths in the listed groups. Those counts should be interpreted in light of the small at-risk numbers and the absence of reported follow-up details. They cannot establish that adverse events are impossible, or that event risks are equal across assignments.

The record does not explain why the trial was terminated, whether the posted information represents all collected data, or what conclusions investigators drew. Those details are not reported in the registry record. The defensible interpretation is therefore narrow: the registry documents the trial's design, enrollment, endpoint description, and recorded event counts, but it does not furnish an analyzed efficacy result or a comparative safety estimate.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a design and an analyzed result. Randomized, double-masked, parallel-group methods describe intended safeguards and organization. They do not by themselves produce an interpretable estimate. A useful treatment comparison also requires outcome measurements, a clearly specified contrast, an analysis population, and reporting of the estimate and its uncertainty. The registry record does not contain those analysis results.

The primary endpoint is tied to a particular procedural moment: blood serum glucose levels between induction and immediately before infusion. That specificity helps identify what was meant to be measured, while the absence of units, a summary method, and a single comparison illustrates why an endpoint label alone is not a complete analysis specification. The record states that the primary outcome has several categories or time points and was not reduced to one comparison. This makes the missing analysis plan especially relevant to interpretation.

The record also demonstrates why safety counts and efficacy results should be kept distinct. It lists zero adverse events in the reported categories, but the at-risk counts are very small and no follow-up details are given. Those descriptive counts cannot stand in for a comparative safety analysis. Similarly, a planning illustration cannot stand in for an observed estimate, and it should not be described as observed power.

Finally, the termination status and the registry's statement about insufficient enrollment are important context, but they do not explain the reason for stopping or determine the direction of any treatment effect. Statistically, the key lesson is that transparent limits matter: when the record has no analysis, conclusions must remain limited to the design and the descriptive information actually reported.

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 most direct limitation is enrollment of four, alongside the registry statement that the study did not reach sufficient enrollment power for statistical analysis. No inferential analysis is reported. The primary glucose outcome has no posted numerical result, unit, estimate, or uncertainty interval. It is therefore not possible to assess the magnitude or precision of a between-group contrast from the registry record.

The treatment descriptions are incomplete. Although Control, Pre-Isolation Infusion, and Post-Isolation Infusion are named, the arm descriptions are blank. The summary refers to nitrite administration to pancreatic islet cells removed for autotransplantation, and the endpoint timeframe refers to nitrite or saline infusion, but detailed procedures and exact arm assignments are not reported. Allocation ratio, randomization procedures, and the implementation of double masking are also not described.

The primary outcome is not reduced to one comparison because it has several categories or time points. The registry does not specify a single primary contrast, a summary measure, or a statistical model. It lists eight outcome measures but reports zero analyses; multiplicity handling is not described. The analysis population, missing-data approach, measurement completeness, and protocol deviations are not reported.

The record gives the status as terminated, but does not give the reason for termination. It does not report a sample-size justification or clarify whether the planning assumptions described for an illustration formed part of the trial's original design. Safety information is limited to event counts and numbers at risk, without follow-up duration or event-collection detail. These limitations restrict both efficacy interpretation and assessment of the safety counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Nitrite Infusion in Islet Cell Transplantation — NCT03544242.
• Registry record last updated 2020-10-29; status last verified 2020-10.
• Results first posted 2020-08-18.
• 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

NCT03544242 is a phase 2 randomized, double-masked, parallel-group trial sponsored by the University of Alabama at Birmingham. It investigates nitrite infusion in islet-cell transplantation and lists Control, Pre-Isolation Infusion, and Post-Isolation Infusion arms. Enrollment was four; the registry status is terminated. The primary outcome is blood glucose serum levels measured between induction and immediately before infusion of nitrite or saline, using a blood sample described as 3-5 cc.

The registry states that the study did not reach sufficient enrollment power for statistical analysis and reports zero analyses. It provides no numerical primary-outcome result or treatment comparison. Safety records list zero serious adverse events, zero other adverse events, and zero deaths in the named groups. The reason for termination, detailed arm procedures, analysis population, missing-data methods, and multiplicity approach are not reported in the registry record. The posted information supports a description of the design and recorded counts, but not an efficacy estimate or comparative safety conclusion.