Allogeneic Islet Cells Transplanted Onto the Omentum: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Allogeneic Islet Cells Transplanted Onto the Omentum (NCT02213003), a na phase 1, phase 2 study. The primary outcome is A1c </= 6.5% and no Severe Hypoglycemia.

2. Clinical Question

The study addresses the transplantation site, rather than a randomized comparison between treatments. Its stated rationale is that transplantation into the liver has limitations, including inflammation, procedure-related risks, exposure to potentially toxic substances, difficulty retrieving transplanted islets, and graft dysfunction. The registry summary proposes the omentum as an alternative site and anticipates that it could support engraftment and functional outcomes comparable or superior to the traditional intrahepatic site. Those statements describe the rationale; they are not findings established by the registry record.

The primary question combines a glycemic measure with freedom from severe hypoglycemia. This asks whether participants met both conditions during the stated follow-up window, not whether either condition alone was achieved. The observed proportion for this composite outcome is not reported in the registry record. No treatment-effect estimate against a comparator is available in the record, so the study cannot establish a comparative effect from the information reported.

3. Trial Design

The registry record lists this study as Phase 1 and Phase 2, with a single-group model, no masking, and allocation recorded as NA. It reports enrollment of 3 and a completed status. The start is recorded as 2014-09, and primary completion as 2024-06-30. These registry entries describe the study structure and administrative record; they do not supply an outcome analysis.

Participants received allogeneic islet transplantation onto the omentum. The arm description specifies at least 5000 islet equivalents/kg of body weight. Because the design is single-group, the record does not describe a concurrent control group for a direct treatment comparison. The registry also explicitly notes that the study is not a randomized comparison and that its arms are not a like-for-like control comparison. A before-and-after comparison, if conducted, would require its own analysis details, which are not reported in the registry record.

The primary endpoint is defined over the period from day 28 to day 365 after transplantation. The registry lists two outcome measures, but detailed results for the primary endpoint are not reported in the registry record. The record lists no analyses. It does not report the allocation process beyond NA, how masking was handled beyond NONE, or whether the protocol changed during the study.

In a single-group study, outcomes can describe what was observed among participants who received the intervention, but they do not by themselves separate intervention effects from other influences. Without a concurrent comparator and a reported analysis, the registry information supports a description of the design and endpoint, not a causal estimate of comparative benefit or harm. The small enrollment also means the study record offers little basis for precise population-level estimates, even if outcome counts were available.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as A1c </= 6.5% and no Severe Hypoglycemia, measured over From day 28 to day 365 after omentum islet transplant.

The primary endpoint is the proportion of participants who had an HbA1c level at or below 6.5% and were free of severe hypoglycemic events after omentum islet transplantation. The assessment period is from day 28 to day 365 after transplant. As a composite outcome, it requires both the glycemic threshold and absence of severe hypoglycemia; satisfying only one condition would not meet the stated definition.

A proportion is appropriate for an endpoint that classifies each participant as meeting or not meeting a specified condition over a defined period. The composite reflects two clinically relevant aspects named in the registry: a laboratory measure of glycemia and the occurrence of severe hypoglycemia. Combining them gives a single summary of participants meeting both criteria, but it can conceal different patterns within the components. For example, the composite alone would not show how many met the HbA1c criterion but experienced severe hypoglycemia, or how many avoided severe hypoglycemia without meeting the HbA1c threshold.

The registry describes the endpoint but does not report its observed proportion, component counts, or an uncertainty interval. Therefore, the endpoint’s actual result and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a proportion measure?

For a binary endpoint, each participant is classified according to whether the defined event or condition occurred. A proportion expresses the number meeting the definition relative to the number assessed. In this study, the event is not simply an HbA1c result or a severe hypoglycemic event: it is meeting the stated HbA1c threshold while also having no severe hypoglycemic events during the specified period. The registry record does not report the primary endpoint proportion or the underlying endpoint counts.

General explanation: a proportion is easy to interpret, but its precision depends on the amount of information in the data. With few observations, a single participant’s classification can materially change the estimate. Reporting a confidence interval alongside a proportion helps readers distinguish the observed estimate from the uncertainty around it. A confidence interval is not a guarantee that the true value lies within the interval; it is an interval produced by a method with stated statistical properties under its assumptions. No such interval is reported for the primary endpoint in the registry record.

Why does the composite definition matter?

The endpoint combines two criteria. A participant must satisfy both to count as meeting the composite. This can be useful when a study aims to describe a joint clinical target, but a composite result does not automatically describe each component separately. Component-specific results can reveal whether the overall pattern reflects the HbA1c criterion, freedom from severe hypoglycemia, or both. Those component results are not reported in the registry record.

The follow-up window also forms part of the endpoint definition. The record specifies assessment from day 28 to day 365 after transplantation. It does not explain how events outside that period were treated, how incomplete observation within the period was handled, or whether the timing of HbA1c measurements was standardized. Such details matter because endpoint classification depends on the operational rules used to decide whether the criteria were met.

What does a single-group design allow?

A single-group study can describe outcomes among people receiving the intervention. It does not, by itself, provide a direct comparison with another intervention or with no intervention. Differences from an external benchmark or a participant’s earlier status could be affected by differences in who was included, how outcomes were measured, and what happened over time. The registry record does not report a comparator or a comparative analysis.

General explanation: random allocation in a controlled trial is intended to make comparison groups similar, on average, with respect to known and unknown factors. That rationale does not apply as a between-group comparison when the study is listed as single-group. Consequently, an observed post-transplant outcome should not be described as an effect attributable to transplantation without supporting design and analysis information.

How should the planning illustration be read?

The registry text describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also describes planning for a stated fraction of the observed effect. These assumptions belong to a planning exercise, not a record of the study’s observed power. The record does not report the planning illustration’s numerical results in the registry record for this explanation, nor does it say that those assumptions were the trial’s own design basis.

General explanation: a sample-size calculation asks how many observations a future study might need under assumptions about the effect, variability, significance level, and desired power. Changing the assumed effect changes the planning result. An illustration using a fraction of an observed effect is therefore conditional on that chosen fraction and on other assumptions; it is not proof that a study with a particular enrollment had adequate power. The posted planning assumptions also describe equal allocation between two arms, while this registry record identifies a single-group study. That distinction is important: planning scenarios are not evidence that the completed study included the groups assumed in a calculation.

What is not described about the analysis?

The registry lists no analyses. It does not report whether the primary endpoint was assessed with a specific statistical test, whether any estimates were adjusted, or whether an uncertainty interval was calculated. It also does not provide endpoint counts or a numerical result. Without those details, readers cannot reproduce an analysis or assess whether its assumptions were appropriate.

General explanation: statistical methods should match the endpoint and design. For a binary outcome, methods may estimate a proportion and its uncertainty. If a comparison is intended, the analysis must account for the groups and allocation structure actually used. A model cannot compensate for the absence of a suitable comparator, and a small data set may limit the stability of more complex adjustment. These are general considerations, not claims about analyses performed in this study.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Islet Transplantation.")
n      <- c(3)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Islet Transplantation.  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures and no analyses. It does not report a multiplicity strategy, such as whether one endpoint was designated as the sole confirmatory test or whether adjustments were planned for testing multiple outcomes. Multiplicity concerns arise when several outcomes or hypotheses are examined, because repeated testing can increase the chance of finding an apparently notable result by chance. The record does not provide enough information to determine whether or how that issue was addressed.

Missing-data handling is also not reported in the registry record. There is no description of how absent HbA1c measurements, incomplete follow-up, or unknown severe hypoglycemia status would affect endpoint classification. The record does not state whether missing values were excluded, imputed, or treated under another rule. These choices can affect a proportion, especially when the endpoint requires information about both criteria across a follow-up period.

The analysis population is not described. The registry does not state whether results were intended for all enrolled participants, participants who received transplantation, or a defined subset. Although enrollment is reported as 3, no primary-outcome denominator or participant flow is reported. The status of participants for the primary endpoint is therefore not reported in the registry record.

General explanation: multiplicity, missing data, and analysis-population definitions are related to interpretation because each affects what an estimate represents and how much confidence to place in it. Their absence from the registry record does not prove that no plans existed; it means the record does not report them. No assumptions should be made about these procedures.

12. 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.

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 3 participants at risk for serious adverse events. It also reports 3 participants at risk for other adverse events and 3 affected by other adverse events. Deaths are recorded as 0. These figures are counts, not a detailed account of event types, timing, duration, severity beyond the serious/non-serious grouping, or relationship to transplantation.

The figures should be read descriptively. The record does not identify the specific other adverse events or provide participant-level detail. It also does not report how events were collected or monitored. Accordingly, the other-event count cannot be interpreted as evidence about the nature or clinical importance of those events.

General explanation: observing no serious events in a small study does not establish that the risk is absent. A limited number of observations provides limited information about uncommon events, and the study record’s safety counts cannot by themselves compare risk with another treatment or site. The registry does not report a control group or a comparative safety analysis. These counts therefore describe what the record reports for this group, rather than demonstrating a safety advantage or resolving the possibility of serious harm.

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

The registry record describes an investigation of allogeneic islet transplantation onto the omentum and defines a primary outcome combining HbA1c at or below 6.5% with no severe hypoglycemia during the stated follow-up period. It also records enrollment, design features, completion status, and adverse-event counts. These details establish what the study set out to examine and what limited safety information is available.

The primary endpoint result is not reported in the registry record. There is no reported proportion, endpoint count, or precision estimate from which to judge how often participants met the composite definition. The record therefore cannot establish whether the target was met in the enrolled group, and it cannot support a quantitative claim about the outcome.

The study is listed as single-group, with no like-for-like control comparison. Even if an outcome estimate were available, a single-group result would describe observations among those receiving the intervention and would not by itself show what the outcome would have been under another approach. The registry summary’s expectation of comparable or superior outcomes at the omentum is a stated rationale, not a finding.

The reported adverse-event figures are also limited. Zero serious events are recorded among 3 participants at risk, while other adverse events are recorded for 3 participants at risk and 3 affected. These counts do not provide details about event types or establish comparative safety. The small enrollment further limits the precision and scope of any conclusions that could be drawn from observed counts.

General interpretation: statistical evidence is strongest when the outcome, analysis, uncertainty, and comparison all match the question being asked. Here, the endpoint is defined, but its result and analysis are not reported in the registry record. The appropriate conclusion is therefore about what was registered and reported, not about whether the intervention achieved a clinical benefit or whether it is preferable to another transplantation site.

14. Why This Trial Matters Statistically

This study is statistically notable because its clinical question is expressed as a clearly defined composite endpoint, while the registry record does not report the corresponding outcome result. That contrast illustrates why an endpoint definition alone is not enough for interpretation: readers also need the observed data, the analysis population, and a measure of uncertainty to understand what was found.

The design also highlights the distinction between describing outcomes and estimating comparative effects. A single-group study can document experience following an intervention, but it does not provide the concurrent comparison needed to isolate differences between interventions. The registry’s stated interest in comparing the omentum with the traditional intrahepatic site is therefore broader than what can be established from the reported design and results information.

Enrollment of 3 makes precision especially important. General statistical principle: when the information base is small, estimates can be sensitive to individual observations, and uncertainty should be made visible rather than hidden behind a point estimate. In this record, the primary estimate and its precision are not reported, so readers cannot judge the strength of evidence for the composite outcome.

The safety counts illustrate a related point. A zero count for serious adverse events is an observation in a small group, not proof of zero risk. Counts of other adverse events without descriptions also cannot characterize the event burden in detail. Statistical reporting is most useful when counts are accompanied by clear definitions, follow-up information, and analysis methods.

Finally, the planning assumptions described in the registry text should be kept separate from the completed study’s evidence. A sample-size illustration is conditional on its assumptions and cannot substitute for a reported outcome analysis. This distinction helps prevent planning calculations from being mistaken for observed power or for proof that a study answered its clinical question.

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 direct limitation of the registry record is that it defines the primary endpoint but does not report its result. The primary-outcome proportion, component-specific results, and uncertainty are not reported in the registry record. The listed two outcome measures are not accompanied by detailed outcome findings in the information available.

The single-group design does not provide a like-for-like control comparison. The registry explicitly identifies the study as not randomized and notes that the arms are not a comparable control comparison. The record therefore does not support a direct estimate of how transplantation onto the omentum compares with another transplantation site or treatment.

Enrollment is reported as 3, limiting the amount of information available for estimating outcomes or describing uncommon events. Participant flow, endpoint denominators, and analysis populations are not reported. The registry also does not report how missing measurements or incomplete follow-up were handled, or how severe hypoglycemic events were operationally defined for analysis.

Further limitations include the absence of reported analysis details, such as statistical methods, adjustment procedures, or multiplicity handling. The adverse-event counts do not include event descriptions, timing, or attribution. The record does not report whether outcome assessment was blinded; masking is listed as NONE. These omissions prevent detailed assessment of measurement and analysis procedures.

The registry summary presents the omentum as a proposed alternative site and describes expected comparable or superior functional and clinical outcomes. Those expectations should not be confused with demonstrated results. The completed status and stated primary completion date do not fill the gap in outcome reporting; the primary endpoint result remains not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Allogeneic Islet Cells Transplanted Onto the Omentum — NCT02213003.
• Registry record last updated 2025-08-12; status last verified 2025-07.
• Results first posted 2025-08-12.
• 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

NCT02213003 is a completed Phase 1 and Phase 2, single-group study of allogeneic islet transplantation onto the omentum. The registry record lists no masking, allocation as NA, and enrollment of 3. The intervention description specifies at least 5000 islet equivalents/kg of body weight.

The primary endpoint is the proportion with HbA1c at or below 6.5% and no severe hypoglycemia from day 28 to day 365 after transplantation. Its result is not reported in the registry record. The record reports 0 serious adverse events among 3 at risk, 3 participants affected by other adverse events among 3 at risk, and 0 deaths. Detailed event descriptions and an analysis are not reported.

The study rationale concerns transplantation onto the omentum as an alternative to the liver site. The single-group design and missing primary outcome result mean the record does not provide a comparative estimate or establish the stated expectation of comparable or superior outcomes.