Desensitization in Kidney Transplantation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Desensitization in Kidney Transplantation (NCT00908583), a non-randomized phase 4 study. The primary outcome is Number of Living Donor Transplant Candidates That Are Transplanted.

2. Clinical Question

The clinical question was whether desensitization strategies could help living donor kidney transplant candidates with preformed anti-HLA antibodies reach transplantation. The registry describes the intended primary outcome as the number of candidates who converted to a negative flow T- and B-cell crossmatch through desensitization and were subsequently transplanted. The outcome timeframe was 1 year post baseline.

The registry’s brief summary frames the study as assessing whether deletional strategies would provide effective desensitization. The condition is HLA sensitization, and the official title identifies preformed anti-HLA antibodies in kidney transplantation as the focus. The record does not define further eligibility characteristics or describe the participants’ clinical profiles, so the population should not be generalized beyond the stated candidate group.

The interventions listed are plasmapheresis, bortezomib, rituximab, and methylprednisolone. The phase descriptions indicate that regimens varied: some describe plasmapheresis, and the bortezomib schedules differ across phases. The available descriptions are incomplete, so they do not establish every treatment detail or the exact regimen received by each participant.

This was not a randomized comparison. The registry classifies the study as nonrandomized, unmasked, and single group, while also listing treatment phases with separate safety counts. These features mean the central question is descriptive: how many candidates met the transplant outcome under the study’s desensitization approach? The record does not report that number, so the question cannot be answered from its posted outcome results.

3. Trial Design

The registry identifies NCT00908583, titled “Desensitization in Kidney Transplantation,” as a Phase 4 study sponsored by the University of Cincinnati. It lists the study as completed, with an enrollment of 44. The recorded start was 2009-05 and the primary completion was 2012-11.

The design classifications are nonrandomized allocation, no masking, and a single-group model. There is no randomized control group identified. The record lists Phase 1 through Phase 5, with descriptions distinguishing two-stage phases from single-stage phases. The safety results are also separated by these phase labels. The presence of phase-specific groups does not make them randomized comparison groups; the registry itself cautions that the arms are not a like-for-like control comparison.

The treatment descriptions include rituximab and bortezomib across the listed phases, with plasmapheresis included in the descriptions for Phase 1 and Phase 2. Phase 3’s description names rituximab and bortezomib. The available descriptions for later phases specify denser bortezomib dosing, but the text is incomplete. Methylprednisolone is listed as an intervention, although the available phase descriptions do not establish its use or schedule.

The registry record does not report how participants entered particular phases, whether protocol changes were triggered by earlier results, or whether analyses were planned between phases. It also does not report a statistical analysis plan, a sample-size justification, or details of a control strategy. Those omissions limit reconstruction of how the study evolved and how its overall enrollment was intended to support the primary outcome.

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.

Before assignment: 44 subjects received 52 treatments in this study. 7 subjects were enrolled in multiple phases. Four patients received treatment in two study phases (two patients were enrolled in Phases 1 and 2, one patient was enrolled in study Phases 1 and 3, and one patient was enrolled in Phases 2 and 3). One patient was enrolled in Phases 1, 2 and 4.

Phase 1

Reasons for not completing this period:

Phase 2

Reasons for not completing this period:

Phase 3

Reasons for not completing this period:

Phase 4

Reasons for not completing this period:

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: Forty-four patients received 52 desensitization courses (7 patients enrolled in multiple phases): Phase 1 (n=20), Phase 2 (n=12), Phase 3 (n=10), Phase 4 (n=5), Phase 5 (n=5). "n" refers to the number of patients. Since patients were enrolled in multiple phases the numbers reported show the total enrollment of each phase.

6. Primary Endpoint

The registry lists the primary outcome as Number of Living Donor Transplant Candidates That Are Transplanted, measured over 1 year post baseline.

The primary endpoint is the number of living donor transplant candidates who converted to a negative flow T- and B-cell crossmatch via desensitization and were subsequently transplanted. The registry gives its unit as participants and its timeframe as 1 year post baseline. It is a count of candidates meeting the combined crossmatch-and-transplant description, rather than a continuous measurement or a time-to-event endpoint.

Combining the crossmatch conversion with subsequent transplantation makes the endpoint more specific than measuring antibody-related change alone: it requires both the stated laboratory condition and a transplant. The registry does not explain why this endpoint was selected, whether crossmatch conversion was assessed at prespecified visits, or how a participant who converted but was not transplanted within the timeframe would be classified. Those operational details are not reported in the registry record.

As a count, the endpoint can describe the number of candidates who met the stated outcome. Interpreting that number as a rate would require a denominator and a clear definition of the eligible population at risk for the outcome. The registry gives the overall enrollment, but does not report the primary outcome count or an endpoint-specific analysis population. No confidence interval or other measure of uncertainty for the primary endpoint is reported in the registry record.

Consequently, the endpoint is clinically interpretable in concept, but its result cannot be assessed from the posted outcome information. The record identifies what was meant to be counted and when, but does not report how many participants met the definition.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count describe?

The primary endpoint is a binary-outcome count: each candidate either meets the registry’s combined definition or does not. The reported measure is intended to be the number of participants meeting that definition, not a mean change or a comparison of average values. In general, a count is easiest to interpret when its denominator is clear: the reader needs to know which participants were eligible for assessment and which had outcome data. The registry record does not report the primary endpoint count or its analysis denominator.

Even when a count is available, it does not by itself express precision. A confidence interval is a range of values compatible with the observed data under a specified statistical method. In general, a narrow interval indicates greater precision than a wide interval, while neither interval alone resolves design limitations such as nonrandom allocation. No confidence interval for the primary endpoint is reported in the registry record.

What can the study design establish?

The registry classifies allocation as nonrandomized, masking as absent, and the model as single group. In general, random allocation helps balance measured and unmeasured characteristics across comparison groups, while masking can reduce some forms of ascertainment or management bias. Those protections are not identified for this study. The phase labels and their separate safety counts should therefore not be interpreted as randomized treatment groups.

A difference between phase-specific results, if reported, would not alone show that a change in treatment caused the difference. Participants could differ across phases, and treatment schedules also vary in the descriptions. The registry does not report an analysis accounting for such differences. There is no randomized control comparison identified, and the registry cautions that the arms are not a like-for-like comparison.

How should planning illustrations be read?

Planning estimates are hypothetical calculations about what a future comparison might require under stated assumptions. They are not observed results and are not evidence that the study had a particular probability of detecting an effect. The stated planning assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. For non-time-to-event outcomes, the planning convention is participants per arm.

In general, a sample-size calculation depends on the outcome, the effect to detect, the chosen error rate, allocation, and statistical model. Changing an assumption changes the planning result. A hypothetical equal-allocation comparison does not describe the actual nonrandomized, single-group design or establish that the original enrollment was adequate. The registry record does not report its own sample-size justification. Planning quantities should not be called observed power, which is not a substitute for interpreting the observed estimate and its uncertainty.

Why can binary outcomes require care?

A binary outcome records whether an event or qualifying state occurred. For the primary endpoint, the qualifying state combines crossmatch conversion with subsequent transplantation. General statistical practice distinguishes the number of participants meeting a definition from the proportion meeting it; a proportion requires a specified denominator. For a proportion, uncertainty depends in part on the amount of information in the data. The registry reports neither a primary count nor a corresponding interval.

Over-dispersion is a general issue for count data when variability exceeds what a basic model assumes. It can make standard errors and intervals too optimistic if ignored. The primary endpoint is defined as a participant count, and the registry does not report a model, a dispersion estimate, or an adjustment for over-dispersion. It would be inappropriate to infer that any such method was used.

What analyses are documented?

The record lists zero analysis entries. That means no statistical analysis is documented in the registry record; it does not establish that investigators performed no analysis outside the record. No test statistic, p-value, adjusted estimate, confidence interval, or analysis population for the primary outcome is reported. The record also does not report whether covariates were considered, whether an interim analysis was planned or conducted, or whether missing observations were handled using a particular method.

In general, p-values address how compatible data are with a specified statistical model and null hypothesis; they do not measure effect size or clinical importance. Confidence intervals communicate precision for an estimate, subject to their model assumptions. Neither can be reconstructed from a missing primary result without making unsupported assumptions. The interpretation should therefore remain descriptive and should not imply an inferential finding that the record does not document.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists several outcomes: the primary count of candidates transplanted after crossmatch conversion, overall safety of bortezomib, a 50% decrease in cytotoxic PRA, and acute rejection rate. When multiple outcomes or repeated statistical tests are examined, the chance of at least one apparently notable result can increase. General approaches to multiplicity include identifying a prespecified primary outcome, defining a testing sequence, or adjusting inference. The registry does not report a multiplicity strategy or a detailed statistical analysis plan. No inferential results are listed, so the record does not show whether any adjustment was applied.

Missing-data methods are also not described. The primary outcome has a 1 year post-baseline timeframe, but the record does not state how incomplete follow-up, unavailable crossmatch results, transplantation outside the timeframe, or other unobserved outcomes were handled. It does not report the number of participants with endpoint data or a flow of participants through assessment. Without these details, the risk that missingness could affect the endpoint interpretation cannot be evaluated.

The analysis population is not specified. The registry does not say whether the primary outcome was analyzed in all enrolled candidates, only candidates with a living donor, or another defined group. A prespecified population definition matters because exclusions or unavailable outcomes can change the denominator and interpretation of a count.

These omissions do not establish that the investigators lacked plans or conducted no analyses. They mean that the multiplicity procedure, missing-data handling, and analysis populations are not reported in the registry record. The posted outcomes therefore do not permit assessment of these aspects of the statistical analysis.

11. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: nausea/vomiting (40.0%), blurred vision (20.0%), headache (20.0%), diarrhea (20.0%), hypocalcemia (20.0%).

The registry reports serious and other adverse-event counts separately for each listed phase. For serious events, the at-risk and affected counts are Phase 1, Two Stages: 20 and 6; Phase 2, Two Stages: 12 and 1; Phase 3: 10 and 4; Phase 4, Single Stage: 5 and 2; and Phase 5, Single Stage: 5 and 2. The corresponding other-event counts are 20 and 2; 12 and 4; 10 and 4; 5 and 0; and 5 and 1, respectively. These are phase-specific registry counts, not randomized comparisons.

The registry also lists serious-event terms and percentages: nausea/vomiting, 40.0%; blurred vision, 20.0%; headache, 20.0%; diarrhea, 20.0%; hypocalcemia, 20.0%; and perivascular dermatitis, 20.0%. The denominator and the method used to summarize these terms are not reported in the registry record. These percentages should therefore be read as the registry’s listed values, not assumed to represent a risk for every participant or a comparative risk between regimens.

Deaths are not reported in the registry record. The safety counts do not establish causation, and the nonrandomized phase structure limits comparisons across treatment schedules. The record does not provide further information on event timing, duration, severity grading beyond the serious-event category, or exposure-adjusted rates.

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

The registry record establishes that this completed Phase 4 study examined desensitization in kidney transplant candidates with HLA sensitization. It identifies a primary endpoint focused on living donor candidates who achieved negative flow T- and B-cell crossmatches through desensitization and were subsequently transplanted within 1 year post baseline. It also records enrollment of 44 and provides selected safety counts for five phase-labeled groups.

The record does not report the primary endpoint result. It therefore cannot show how many participants met the endpoint, how precisely that outcome was estimated, or whether the observed result differed from any comparator. The listed secondary outcomes also have no numerical results in the registry record. A completed status indicates the study is recorded as completed; it does not substitute for reported outcome findings.

The safety counts describe reported events among the phase-specific at-risk groups. They do not establish that a treatment caused an event, and they do not support direct comparisons across phases. Nonrandom allocation and differences in the phase descriptions make such comparisons especially difficult to interpret. The serious-event term percentages are listed without a reported denominator, which further constrains interpretation.

In general, an observed outcome and its uncertainty are needed to assess the size and precision of a result; an appropriate comparison is needed to estimate a treatment effect. Neither a missing result nor a planning illustration supplies that evidence. The planning assumptions concern a hypothetical comparison and are not observed power or a trial result.

Accordingly, the defensible reading is limited: the registry describes the study question, design classifications, intended endpoint, treatment components, and selected safety information. It does not provide enough outcome or analysis detail to establish the frequency of the primary endpoint or to draw a comparative effectiveness conclusion.

13. Why This Trial Matters Statistically

This study illustrates why registry design labels and outcome reporting are central to statistical interpretation. The record asks a clinically defined question about desensitization followed by transplantation, but identifies a nonrandomized, unmasked, single-group model and no like-for-like control comparison. That distinction determines what the data could support: a descriptive account of outcomes under the study approach is different from an estimate of how the approach compares with an alternative.

The phase-specific safety counts also highlight the importance of describing treatment cohorts carefully. Different phase labels and regimen descriptions do not create exchangeable groups. General statistical reasoning requires attention to how participants entered each group, how protocols changed, and whether follow-up and outcome definitions were consistent. Those details are not reported in the registry record, so the phase-specific counts should not be read as causal contrasts.

Endpoint definition matters as well. The primary outcome combines crossmatch conversion with subsequent transplantation in a stated timeframe. This is more informative than a laboratory change alone, but its interpretation depends on a reported count, denominator, and handling of incomplete follow-up. The record gives the definition and timeframe but no result.

Finally, a completed registration without listed analyses demonstrates the difference between a registered objective and an interpretable result. Transparent reporting of estimates, uncertainty, analysis populations, and missing-data handling is necessary for readers to evaluate precision and limitations. The record contains useful design and safety details, yet its unreported primary outcome prevents assessment of the central question.

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 that the primary endpoint result is not reported in the registry record. The number of candidates meeting the combined crossmatch and transplant definition is absent, as are its denominator and measure of uncertainty. The secondary outcomes likewise have no numerical analyses listed.

The design limits comparative interpretation. Allocation is recorded as nonrandomized, masking as absent, and the model as single group. No like-for-like control comparison is identified. The phase-specific safety counts cannot remove confounding or establish that any differences between phases are attributable to regimen differences.

Several details needed to understand the groups are not reported: how candidates were assigned to phases, how many participants were assessed for each outcome, whether all phase participants had comparable follow-up, and whether the described regimen changes were planned or reactive. The treatment descriptions are incomplete, and methylprednisolone is listed as an intervention without a corresponding regimen detail in the available phase text.

The registry does not report a statistical analysis plan, a sample-size justification, an analysis population, multiplicity handling, missing-data methods, interim analyses, or endpoint-specific estimates. For the serious-event term percentages, the denominator and calculation context are not stated. Death counts are not reported in the registry record.

These gaps do not establish that the information was unavailable to investigators; they limit what can be concluded from the registry record. The study’s enrollment and completion status do not resolve missing outcome and analysis details, and the planning assumptions do not replace observed results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Desensitization in Kidney Transplantation — NCT00908583.
• Registry record last updated 2016-04-01; status last verified 2016-03.
• Results first posted 2016-02-26.
• 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

NCT00908583 is a completed Phase 4 study titled “Desensitization in Kidney Transplantation,” sponsored by the University of Cincinnati. The registry records enrollment of 44, a start date of 2009-05, and primary completion in 2012-11. Its design is classified as nonrandomized, unmasked, and single group.

The study concerns HLA sensitization and preformed anti-HLA antibodies in kidney transplantation. Listed interventions are plasmapheresis, bortezomib, rituximab, and methylprednisolone. The primary outcome is the number of living donor transplant candidates who converted to negative flow T- and B-cell crossmatches through desensitization and were subsequently transplanted, with a timeframe of 1 year post baseline.

The record lists phase-specific safety counts and several serious-event terms. It does not report the primary outcome result, secondary outcome analyses, analysis populations, or detailed statistical methods. The registry cautions that the phase groups are not like-for-like control comparisons.