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 Early Conversion From Tacrolimus to Efalizumab Maintenance Therapy in Kidney Transplant Recipients (NCT00472082), a na phase 1, phase 2 study. The primary outcome is Efficacy Will be Determined by Change in Renal Function as Measured by Cold Iothalamate Glomerular Filtration Rate(GFR)3 Months After Enrollment, and Acute Rejection Episodes Within the First 6 Months Post Enrollment..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00472082 |
| Phase | Phase 1, Phase 2 |
| Condition | Kidney Transplantation, Chronic Kidney Failure |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Emory University |
| Results posted | Yes |
2. Clinical Question
Population
Primary renal transplant recipients with mild impairment of renal function were the intended population, according to the study summary. The registry record lists kidney transplantation and chronic kidney failure as conditions. It reports enrollment of 5, but further eligibility details and characteristics of the enrolled participants are not reported in the registry record.
Intervention
The study aimed to replace tacrolimus with efalizumab early after transplantation. The arm description places efalizumab in a triple-drug regimen that includes mycophenolate mofetil and prednisone. The exact timing of conversion and the full administration schedule are not reported in the registry record.
Comparator
There is no separate control group in the listed single-group design. The record gives allocation as not applicable and masking as none. It therefore does not describe a randomized comparison with continued tacrolimus or another treatment strategy.
Primary question
The primary outcome description identifies change in renal function measured by cold iothalamate glomerular filtration rate, with assessment 3 months after enrollment, and acute rejection episodes during the first 6 months after enrollment. The listed timeframe is 6 months from conversion. Outcome values and analyses are not reported in the registry record.
The clinical rationale in the record is that toxicity of calcineurin inhibitors is a factor limiting renal transplantation success. The study sought to examine early replacement of tacrolimus in recipients with mild renal-function impairment. That rationale describes the question motivating the pilot; it does not establish that conversion improved renal function or prevented toxicity.
The registry record identifies safety outcomes as well, including post-transplant infections, malignancies, morbidities, hypertension, glucose intolerance, serum cholesterol and triglycerides over time, and development of new anti-donor antibodies. These outcomes broaden the question beyond renal filtration and acute rejection. Their definitions, assessment schedules and results are not reported in the registry record.
3. Trial Design
The registry describes an open-label, single-center pilot study, with Phase 1 and Phase 2 listed. Its official title specifies primary renal transplant recipients. The listed model is single-group, allocation is not applicable, and masking is none. Enrollment is recorded as 5. The status is terminated; the reason for termination is not reported in the registry record.
The study summary says the protocol aimed to replace tacrolimus with efalizumab early after transplantation, in recipients with mild impairment of renal function. The arm description identifies efalizumab as part of a triple-drug regimen including mycophenolate mofetil and prednisone. It mentions a test dose of efalizumab, but the remaining schedule is incomplete in the registry record. The exact conversion timing and duration of treatment are not reported in the registry record.
A single-group design can describe what happened among participants receiving the study regimen, but it does not provide a concurrent comparison group. In general, without such a comparator, changes over time cannot by themselves separate a treatment effect from the natural course after transplantation, changes in other care, or differences in participant characteristics. The record does not identify a tacrolimus continuation group or another control condition.
The listed primary outcome combines a renal-function measure and acute rejection episodes, with the outcome timeframe described as 6 months from conversion. Its detailed description also places the GFR assessment 3 months after enrollment and rejection assessment within the first 6 months after enrollment. The record does not explain the relationship between enrollment and conversion timing. Start is listed as 2007-05, and primary completion as 2009-04; these dates do not establish when each participant began or completed treatment.
The registry lists two outcome measures and no analyses. A protocol-level statistical plan, recruitment history, analysis population, and reasons for termination are not reported in the registry record. The design information therefore supports a description of the study structure and intent, but not a reconstruction of how outcomes were ultimately analyzed.
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 | Efalizumab Conversion |
|---|---|
| STARTED | 5 |
| COMPLETED | 0 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | Efalizumab Conversion |
|---|---|
| Study prematurely terminated | 5 |
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 | Efalizumab Conversion |
|---|---|---|
| Participants analysed | 5 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 4 |
| Age, Categorical: >=65 years | Participants | 1 |
| Age, Continuous | years | 48 (SD 21) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 3 |
| Region of Enrollment: United States | participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Efficacy Will be Determined by Change in Renal Function as Measured by Cold Iothalamate Glomerular Filtration Rate(GFR)3 Months After Enrollment, and Acute Rejection Episodes Within the First 6 Months Post Enrollment., measured over 6 months from conversion.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome description focuses on change in renal function measured by cold iothalamate glomerular filtration rate (GFR), assessed 3 months after enrollment, and acute rejection episodes during the first 6 months after enrollment. The listed timeframe is 6 months from conversion. The registry does not report a GFR value, a change estimate, the number of rejection episodes, or an analysis of either outcome.
In general, GFR is used to assess how effectively the kidneys filter blood. A measured change can help characterize renal function over time, although its interpretation depends on the measurement schedule, baseline values, variability and clinical context. Cold iothalamate GFR is the measurement named in the record; measurement procedures and quality-control details are not reported in the registry record.
In general, acute rejection is a clinically relevant transplant outcome because it reflects an episode of immune activity directed against the transplanted organ. It is not interchangeable with a continuous measure of filtration: GFR describes renal function, while rejection episodes are event outcomes. The record does not specify the rejection definition, adjudication process, or whether rejection was biopsy-confirmed.
Because the record lists two different outcome dimensions and gives no results, it is not possible to determine whether renal function changed, whether rejection occurred, or how precisely either outcome was estimated. The listed timing also leaves the enrollment-to-conversion relationship unclear, so the outcome window should be read using the registry's stated wording rather than an assumed schedule.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a small, single-group pilot and records enrollment of 5. It does not report efficacy analyses, GFR results, or acute rejection results. Consequently, the record does not support an estimate of renal-function change or a conclusion about the frequency of rejection in this study. The absence of a result in the registry record is not evidence that an outcome did or did not occur.
The design limits what can be inferred even if within-group outcome values were available. In general, a single-group study can describe observed measurements among participants receiving the regimen, but it lacks a concurrent counterfactual: what would have happened to comparable participants under another strategy. Without random allocation or a control group, observed changes could reflect treatment, the course of recovery or decline after transplantation, other care, or chance. No randomized comparison is listed.
Precision is also a central concern. In general, estimates from a small pilot tend to be sensitive to individual observations, and their uncertainty can be substantial. The record does not provide a numerical estimate or confidence interval for either primary outcome, so the degree of precision cannot be assessed. Enrollment alone does not indicate what was observed or how reliably an effect was estimated.
The registry lists 2 outcome measures and no analyses. It does not give a statistical analysis plan, analysis populations, missing-data handling, or multiplicity approach. These omissions make it impossible to establish whether the planned outcome descriptions were fully assessed, how any available measurements were summarized, or how selective reporting may have been addressed. The primary outcome timeframe also uses both enrollment-based wording and a timeframe from conversion; the timing relationship is not explained.
The record labels the study terminated, but the reason is not reported in the registry record. Termination alone does not identify whether the study stopped for recruitment, safety, feasibility, administrative, or other reasons. Nor does it establish that the intervention caused harm or that a planned endpoint was reached.
The sample-size assumptions describe a planning illustration based on an observed effect, not the trial's own design. The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a fraction of the observed effect. Such planning calculations are hypothetical and should not be read as observed power or as evidence about the study's actual outcomes. The record does not report a trial-specific sample-size justification.
Overall, the registry is informative about the study's intent, design, listed endpoints and limited safety counts. It does not provide the efficacy results needed to quantify a treatment-associated change. Even a reported within-group change would require cautious interpretation because the design does not offer a like-for-like control comparison.
9. Statistical Methods Explained
Statistical interpretation starts with the question the design can answer. This study is listed as single-group, open-label, and without a comparator. Those features mean the registry does not describe a randomized treatment contrast. Any within-group summaries, if available, would characterize participants in the efalizumab conversion group; they would not, on their own, estimate how outcomes would differ under continued tacrolimus or another strategy.
What does a single-group result represent?
In general, a before-and-after comparison describes measurements at different times in the same study group. It can show the direction and size of observed change if baseline and follow-up data are reported. Such a change is not automatically attributable to treatment. Transplant recipients may experience changes over time for reasons unrelated to the study regimen, and other aspects of care can also change. A concurrent comparator helps address these alternative explanations, particularly when treatment allocation is randomized. No such comparison is listed in this record.
Here, the registry specifies cold iothalamate GFR and acute rejection episodes as primary outcome components, but gives no outcome values or analyses. Without baseline and follow-up GFR summaries, the direction, magnitude and variability of renal-function change cannot be evaluated. Without rejection counts or a defined analysis, the event outcome cannot be characterized. These are missing results in the registry record, not estimates that can be reconstructed from the design description.
Why does uncertainty matter?
In general, an estimate describes the observed data, while a confidence interval describes the range of values reasonably compatible with those data under the model used. Wider intervals indicate less precision; narrower intervals indicate greater precision, subject to the model and data quality. The registry record does not report estimates or confidence intervals for the primary outcomes, so precision cannot be quantified. A small pilot can be useful for feasibility and descriptive information, but its estimates can be unstable and may not represent outcomes in a broader population.
A p-value, when reported, addresses compatibility between data and a specified null model under particular assumptions. It does not measure the size or clinical importance of an effect, and it does not establish causality. No p-values or inferential analyses are listed in this record. In a single-group study, a test of change over time would still not replace a controlled treatment comparison: statistical significance of change would not rule out time trends or other explanations.
How should the planning assumptions be read?
The stated sample-size assumptions describe a planning illustration rather than the study's own design. The illustration is based on an observed effect, uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, and considers an effect defined as a fraction of the observed effect. These assumptions describe a hypothetical future comparison framework. They do not indicate that this single-group study used equal allocation, and they do not convert the study into a randomized comparison.
In general, a planning calculation asks how much information a future study may need to detect a chosen effect under specified assumptions. Its result depends on the effect size, outcome variability, significance level, allocation, and analysis method. If the effect used as a planning reference is uncertain or exaggerated, the resulting planning estimate can also be uncertain. Planning illustrations are not observed power, and they do not describe the probability that the completed study established an effect. No trial-specific sample-size justification is reported in the registry record.
What is the role of outcome scale?
GFR is a quantitative measurement, so useful reporting generally includes the measurement scale, summaries at relevant times, and a change estimate with uncertainty. The meaning of a change depends on the baseline level, the timing and reliability of measurements, and how missing observations are handled. The record names the measure and a follow-up time but does not report those summaries or measurement details.
Acute rejection is an event outcome. In general, interpreting an event count requires a clear event definition, the number of participants assessed, and the observation period. If follow-up differs between participants, time at risk can matter. The record identifies a timeframe but does not state event definitions, adjudication procedures, participant-level follow-up, or an analysis. It is therefore not possible to evaluate event rates or compare risk across strategies.
Safety outcomes can also be described by whether participants experienced an event and by event counts, severity, timing, and relatedness. These are distinct summaries: a participant count is not necessarily the same as an event count if participants can experience repeated events. The registry's safety figures should therefore be read as the categories and counts it reports, without inferring unreported event totals or causation.
Finally, statistical methods are only one part of interpretation. The design, endpoint definitions, completeness of follow-up, and transparency of reporting determine which conclusions are supportable. In this record, the design and intended outcomes are described, but efficacy analyses, outcome-level precision, and several analysis details are not reported. General statistical concepts can clarify the limits, but they cannot fill in absent results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 2 outcome measures and identifies a primary outcome with renal-function and acute-rejection components. It also lists safety outcomes spanning infections, malignancies, morbidities, hypertension, glucose intolerance, lipid profiles over time, and new anti-donor antibodies. Assessing several outcomes can raise a multiplicity issue: in general, the more hypotheses examined, the greater the chance that at least one result appears notable by chance if each is considered separately. Whether and how this issue was addressed is not reported in the registry record.
The record lists no analyses. It does not report a statistical analysis plan, a hierarchy among outcome components, multiplicity adjustment, or whether analyses were prespecified. It is therefore not possible to determine which results were intended as confirmatory and which, if any, were exploratory. The registry's endpoint description should not be interpreted as evidence that every listed outcome was analyzed.
Missing-data handling is also not reported in the registry record. There is no description of the number of participants with outcome measurements, reasons for missing observations, imputation, or sensitivity analyses. In general, missingness can affect estimates when participants without follow-up differ from those with observed outcomes. The direction and extent of any such effect cannot be assessed without information about completeness and the analysis approach.
Analysis populations are not reported in the registry record. It is not specified which participants would be included in each outcome analysis or how discontinuation or protocol deviations would be handled. The reason for termination is also not reported. These gaps prevent assessment of whether analyses followed an intended plan or whether the available observations represent the enrolled group.
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 |
|---|---|---|---|
| Efalizumab Conversion | 2 | 5 | 40.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Efalizumab Conversion | 0 of 5 |
Most frequent serious adverse event terms
| Event term | Organ system | Efalizumab Conversion |
|---|---|---|
| Hospitalization | Infections and infestations | 2 of 2 |
Serious events with the highest arm-level rate: hospitalization (100.0%).
The registry's adverse-event figures list the Efalizumab Conversion group with 5 at risk for serious events and 2 affected. For other adverse events, it lists 5 at risk and 0 affected. These are the posted counts; they do not establish that efalizumab caused an event or that the absence of a reported event means the regimen was free of risk.
Hospitalization is listed among the serious-event terms with 100.0%. The denominator and the underlying event count for that term are not reported in the registry record, so the percentage should not be translated into a count or interpreted as a participant-level risk. The record does not state whether the term describes participants, events, or another reporting unit.
In general, serious adverse-event summaries are distinct from all adverse-event summaries. A serious event classification does not by itself show treatment relatedness, and one participant may experience more than one event. The registry does not report event timing, severity beyond the serious classification, relatedness assessment, or detailed event narratives. Deaths are not reported in the adverse-event figures.
These figures should be read as limited registry safety reporting from a small, single-group study, not as a comparative safety estimate. A control group and fuller event-level information would be needed for a stronger comparative assessment.
12. What the Result Does, and Does Not, Mean
The record establishes that Emory University sponsored an open-label, single-center pilot study intended to examine early conversion from tacrolimus to efalizumab maintenance therapy in primary renal transplant recipients. It identifies a single-group design, enrollment of 5, a terminated status, and primary outcomes concerning cold iothalamate GFR and acute rejection. It also provides limited adverse-event counts. Those details describe the trial's structure and reporting; they do not establish the clinical effect of the regimen.
The registry does not report primary outcome results or statistical analyses. There is no reported GFR change estimate, uncertainty interval, rejection result, or comparative treatment effect. It is therefore not possible to say from this record whether renal function improved, worsened, or remained similar, or whether acute rejection occurred. The absence of efficacy results should not be treated as a null result.
Even if within-group changes were available, the single-group design would not establish what would have happened under another treatment strategy. In general, causal interpretation is strengthened by a suitable comparator and randomized allocation, which can reduce systematic differences between treatment groups. Neither is listed. Open-label conduct can also affect outcome assessment or care, depending on the outcome and methods; the registry does not describe safeguards against such influence.
The safety figures indicate that serious events and other adverse events were recorded in the registry, including the listed hospitalization term. They do not provide a detailed account of event timing, severity, relatedness, or comparative risk. The terminated status does not explain why the study ended, and it should not be read as evidence of either safety failure or efficacy.
The study can be understood as a pilot addressing a specific conversion strategy and recording outcomes of interest. Its registry entry does not supply enough outcome information to judge efficacy or quantify precision. Its design also limits causal conclusions. Any broader interpretation would require fuller results and methods, which are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial matters statistically because its design illustrates the distinction between describing outcomes and estimating a treatment effect. A single-group study can document measurements and events among participants receiving a regimen, but it does not provide a concurrent comparison. That distinction remains important even when the clinical question is motivated by a plausible concern about treatment toxicity.
The record also illustrates why endpoint specification and result reporting are essential. The primary outcome description includes a quantitative renal-function measure and an event outcome, with timing expressed in relation to enrollment and conversion. These outcomes require different summaries and different interpretation. Without reported values, uncertainty estimates, and clear analysis details, readers cannot determine the direction, magnitude, or precision of the results.
Pilot studies can contribute descriptive information about feasibility and can help identify questions for further study. In general, however, a pilot estimate based on a small group is vulnerable to instability, and a planning illustration based on an observed effect is not evidence that the effect is reliable. The sample-size assumptions in this record are explicitly described as a planning illustration rather than the trial's own design.
Finally, the registry's limited safety figures demonstrate why denominators, definitions, event-level detail, and comparator information matter. Counts and a percentage can be difficult to interpret when the reporting unit or denominator is not specified. Transparent reporting of outcome results, missingness, analysis populations, and study termination would make the evidence easier to assess. Those details are not reported in the registry record.
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.
Several limitations are specific to the information available for this study. The registry reports enrollment of 5 and a single-group design, without a concurrent control. The record therefore cannot support a controlled comparison, and the small enrollment limits the descriptive information available for estimating outcomes precisely.
The status is terminated, but the reason is not reported in the registry record. The entry does not explain whether termination was related to recruitment, feasibility, safety, administration, or another factor. It also does not report whether all enrolled participants completed follow-up or received the intended regimen.
The primary outcome description gives a GFR assessment 3 months after enrollment and acute rejection assessment within the first 6 months after enrollment, while the listed timeframe is 6 months from conversion. The record does not clarify the relationship between enrollment and conversion or provide the exact assessment schedule. It also does not define acute rejection or report methods for measuring GFR.
The arm description is incomplete, and the full dosing and treatment schedule are not reported in the registry record. Baseline clinical characteristics, detailed eligibility criteria, outcome results, confidence intervals, and analysis methods are also not reported. The registry gives limited safety counts but not event-level details or treatment relatedness. These omissions constrain both clinical interpretation and statistical assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Early Conversion From Tacrolimus to Efalizumab Maintenance Therapy in Kidney Transplant Recipients — NCT00472082.
- Registry record last updated 2014-01-27; status last verified 2013-12.
- Results first posted 2012-12-06.
- 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
NCT00472082 is a Phase 1 and Phase 2, open-label, single-center pilot study of early conversion from tacrolimus to efalizumab maintenance therapy in primary renal transplant recipients. Emory University is listed as sponsor. The record lists enrollment of 5, start in 2007-05, primary completion in 2009-04, and status as terminated.
The single-group study aimed to replace tacrolimus with efalizumab early after transplantation. The arm description includes mycophenolate mofetil and prednisone in the regimen. The primary outcome concerns cold iothalamate GFR and acute rejection; the registry lists no analyses or efficacy results. Safety reporting lists 2 affected among 5 at risk for serious events and 0 affected among 5 at risk for other adverse events. The reason for termination and further outcome details are not reported in the registry record.