UARK 2006-15: A Study of Tandem Transplants With or Without Bortezomib and Thalidomide: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for UARK 2006-15: A Study of Tandem Transplants With or Without Bortezomib and Thalidomide (NCT00574080), a randomized phase 3 study. The primary outcome is Event Free Survival.

2. Clinical Question

3. Trial Design

The registry identifies NCT00574080 as a randomized Phase III study with a parallel-group design and no masking. Participants were assigned to Arm A or Arm B. The treatment contrast was whether VTD was included with the transplant regimens: the Arm B description includes VTD with Melphalan/DPACE at Transplant 1 and with BEAM at Transplant 2, while the Arm A description does not. Both descriptions include DPACE induction and consolidation, dexamethasone maintenance, and interim dexamethasone between treatment phases.

The study concerned multiple myeloma and listed the University of Arkansas as sponsor. The registry gives a start of 2006-07 and primary completion of 2011-03. Its current status is terminated. Enrollment is listed as 20, and the primary outcome description states that the study terminated with <10% of target accrual enrolled. The target number and the reason for termination are not reported in the registry record.

Randomization is intended, in general, to make treatment groups comparable on average by assigning participants through a chance-based process. It does not guarantee balance, especially in a study that stopped with enrollment far below its target. The registry does not report details of the randomization sequence or allocation concealment. With no masking, participants and study personnel could know the assigned treatment; whether outcome assessment was blinded is not reported in the registry record.

The registry lists one primary outcome measure, event-free survival, with a timeframe of up to 3 years 8 months. It reports no primary endpoint analysis and no analyses overall. Therefore the design information describes the intended comparison, but does not support an estimate of the treatment contrast or a conclusion about its precision.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: no analysis, participants either died or were withdrawn by PI. study terminated with \<10% of target accrual enrolled.

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 Event Free Survival, measured over Up to 3 years 8 months.

Event-free survival measures the time from study registration until either disease progression or death. It is a time-to-event endpoint: rather than recording only whether an event occurred by a particular visit, it uses the time until the first qualifying event. The registry lists a timeframe of up to 3 years 8 months.

In general, a time-to-event measure can represent both how often events occur and when they occur, while allowing follow-up time to vary across participants. The event definition must be applied consistently, and participants who have not had an event by the end of their observed follow-up need appropriate handling as censored observations. The registry record does not report the censoring rules or details of event ascertainment.

The endpoint is described as time from registration until disease progression or death. The posted primary outcome contains no numerical estimate, comparison, or analysis. Its population note says that participants either died or were withdrawn by the principal investigator and that the study terminated with <10% of target accrual enrolled. Thus the endpoint's intended meaning is clear, but its observed treatment contrast cannot be assessed from the registry results. No median event-free survival, hazard estimate, confidence interval, or significance test is reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods details that can be established are limited. The registry describes a randomized, parallel-group Phase III study with no masking. It names event-free survival as the primary outcome and defines it as time from registration until disease progression or death. It reports no analyses. A detailed statistical analysis plan, including the specific method intended for the primary endpoint, is not reported in the registry record.

What does randomization contribute?

General statistical explanation: Randomization assigns treatment by a chance-based procedure. When implemented as planned, it can reduce systematic differences in baseline prognostic factors between groups, supporting a fair comparison. It does not ensure that groups will be balanced on every characteristic, and small or incomplete enrollment can leave substantial chance imbalances. The record identifies randomization but does not describe sequence generation, allocation concealment, stratification factors, or checks of baseline balance. Those details are not reported in the registry record.

How is a time-to-event outcome usually analyzed?

General statistical explanation: Time-to-event data include a time origin, an event definition, and each participant's observed follow-up. A participant without a recorded event by the end of available follow-up is commonly treated as censored, rather than assumed to have remained event-free indefinitely. Kaplan–Meier estimates are one general way to describe event-free survival over time; regression methods such as a Cox model can estimate a relative event rate under additional assumptions. These are examples of general methods, not methods confirmed for this trial. The registry record does not report which method, if any, was used or specify censoring rules, model assumptions, covariate adjustments, or a primary effect measure.

A confidence interval, in general, expresses the uncertainty around an estimated effect under the model used. A narrow interval indicates greater precision than a wide interval; it does not by itself establish clinical importance. No primary endpoint estimate or confidence interval is reported in the registry record, so precision cannot be evaluated. Similarly, a significance test cannot be interpreted when the record supplies no test statistic or p-value.

What can the planning assumptions tell readers?

The registry's sample-size assumptions describe a planning illustration, not the study's original design calculation. They specify a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. For time-to-event illustrations, the stated quantity is the total number of events using the Schoenfeld approach; for other outcomes, it is participants per arm. The registry record does not report the trial's own sample-size justification, and the planning assumptions must not be read as observed power.

These assumptions do not supply a treatment effect estimate. The primary outcome has no analysis, and the registry identifies the outcome as not reduced to one comparison. No particular planning illustration can therefore be treated as a trial result. In general, sample-size calculations are conditional on their chosen effect, allocation, significance level, and statistical assumptions. They describe a hypothetical design requirement, not the certainty or validity of an estimate from the enrolled participants.

Why can over-dispersion matter?

General statistical explanation: Over-dispersion occurs when outcome variability is greater than a model assumes. If ignored, standard errors can be too small and confidence intervals too narrow, making statistical evidence appear more precise than it is. It is relevant to some count-data models, but the registry record does not report a count-based primary endpoint or a model that would allow an assessment of over-dispersion. It would be inappropriate to infer that the trial used such a model.

More broadly, a statistical method is only as informative as the data and assumptions supporting it. In this study, no primary endpoint results are posted, and the registry's outcome note records death or withdrawal by the principal investigator. Without event times, censoring information, analysis details, or estimates, readers cannot reproduce an analysis or judge its assumptions. The missing methodological information should not be filled in by assuming a conventional analysis was used.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies event-free survival as the primary outcome, but it does not report an analysis. It also lists no analyses overall. The registry record does not report a multiplicity plan, such as how testing across secondary outcomes, time points, or other comparisons would be handled. The outcome description does not present results across several categories or time points for an analysis, and no single comparative estimate is available.

In general, multiplicity arises when researchers make multiple statistical comparisons. Repeated testing can increase the chance of finding an apparently notable result by chance, so a prespecified strategy may be used to control that risk. This is general context; the registry does not say whether any such strategy was planned or applied. No p-values or other inferential results are posted for the primary endpoint.

The primary outcome note says participants either died or were withdrawn by the principal investigator. Details about the timing, reasons, and distribution of withdrawals are not reported in the registry record. The record does not describe an analysis population, handling of missing outcome data, censoring rules, or sensitivity analyses. In general, missingness can affect estimates if the people with unavailable outcomes differ systematically from those with observed outcomes. Without the relevant details, the direction or size of any such effect cannot be assessed.

The registry's statement about participants who died or were withdrawn is not enough to determine how every participant's follow-up was treated in an analysis. Death is part of the event-free survival definition, while withdrawal may limit observation; the record does not give further endpoint-processing rules. It also does not report whether analyses followed assigned groups or used another population definition. These omissions prevent a fuller assessment of attrition, missing data, and multiplicity.

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 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: death (20.0%), embolus (10.0%).

For serious adverse events, the registry lists 10 at risk and 4 affected for VTD + DPACE/Melphalan, and 10 at risk and 3 affected for DPACE/Melphalan. For other adverse events, it lists 10 at risk and 0 affected in each group. These are the posted counts and should be read as safety entries, not as a comparison of the primary event-free survival endpoint.

The record lists death, 20.0%, and embolus, 10.0%, as the top serious-event terms. It does not report the basis for these percentages or provide a group-specific breakdown for those terms. The deaths field for each group is null, so group-specific death counts are not reported in the registry record. The listed serious-event term percentages cannot be assumed to be arm-specific risks.

In general, adverse-event counts need context: the reporting period, event definitions, exposure time, severity grading, and whether counts refer to people or events can all affect interpretation. These details are not reported in the registry record. The listed at-risk and affected counts do not establish that an event was caused by treatment, and the small enrolled population and early termination limit what can be learned from these entries. No comparative safety analysis is reported.

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

The registry record documents a randomized comparison of tandem transplant regimens with and without VTD during the transplant phases. It also records the stated primary outcome, event-free survival, and reports some adverse-event counts. These registry entries describe the study's question and the information posted about safety; they do not answer whether adding VTD changed event-free survival.

There is no primary endpoint estimate, effect size, confidence interval, or statistical test in the posted results. Consequently, the record does not show the direction or magnitude of a treatment difference, nor how precisely a difference could be estimated. A lack of a reported result must not be interpreted as evidence of no difference or equivalence. Equivalence or non-inferiority would require an appropriate design and analysis, neither of which is reported as a result.

Enrollment is listed as 20, and the primary outcome note states that the study terminated with <10% of target accrual enrolled. This makes the absence of a completed comparative analysis especially important: the record does not provide the information needed to assess how the intended question performed in the enrolled participants. It also does not give a reason for termination, so the cause should not be inferred.

The safety entries are similarly limited. They report affected counts for serious and other adverse events, but do not provide enough detail to establish event attribution, exposure-adjusted risk, or comparative safety. The serious-event terms death and embolus are listed with percentages, but their reporting basis and group allocation are not described. These entries should not be used to infer a causal effect of either regimen.

In general, a trial result is strongest when its endpoint definition, analysis population, treatment estimate, uncertainty, and missing-data handling are all available. Here, the record supplies the endpoint definition and design description but not the primary analysis. The appropriate statistical conclusion is therefore limited: the planned contrast is identifiable, while its effect on the stated primary outcome remains undetermined from the registry results.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction between a study question and an answer to that question. A randomized design can specify a meaningful comparison, but randomization alone does not produce an interpretable treatment-effect estimate. The registry names a primary time-to-event endpoint and describes the treatment arms, yet it reports no analysis of that endpoint.

The record also makes clear why enrollment and study completion matter to interpretation. Enrollment is 20, and the primary outcome note states that the study terminated with <10% of target accrual enrolled. When a study stops far short of its target, the information available may be insufficient for a precise comparison. The registry does not provide an effect estimate or uncertainty measure that would show how much information was obtained in this case.

Statistically, the absence of an analysis is not a null finding. A null result would still require an estimate and uncertainty that permit readers to assess what effects remain compatible with the data. Without those results, neither evidence for a difference nor evidence against one can be evaluated from the posted primary outcome.

The record is also a reminder that safety counts and efficacy endpoints answer different questions. The serious adverse event entries provide limited counts, while event-free survival is a time-to-event endpoint combining progression or death. One cannot substitute the safety counts for the missing efficacy analysis, or interpret a serious-event term as a comparative treatment effect.

For clinical researchers and biostatisticians, this example emphasizes the value of transparent reporting of the analysis population, event handling, censoring rules, effect estimates, confidence intervals, and reasons for missing outcomes. Those details are not reported in the registry record. Their absence narrows what readers can conclude, even when the trial design and intended endpoint are clearly described.

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 consequential limitation is that the registry reports no analysis of the primary endpoint. It gives no event-free survival estimate, treatment comparison, confidence interval, or p-value. The endpoint description and timeframe do not reveal how outcomes differed between arms or how uncertain a comparison would be.

The registry reports enrollment of 20 and states that the study terminated with <10% of target accrual enrolled. The target accrual and reason for termination are not reported in the registry record. The posted primary outcome note says participants either died or were withdrawn by the principal investigator, but does not provide counts by reason or arm, event times, follow-up completeness, or details of how withdrawals were handled.

Important design and analysis details are also absent. The registry record does not report randomization procedures, allocation concealment, baseline characteristics, event adjudication, censoring rules, the statistical model, adjustment variables, an analysis population, or sensitivity analyses. It does not report a multiplicity strategy or the study's sample-size justification. These omissions prevent assessment of whether analysis choices were prespecified and whether assumptions were appropriate.

The safety information is limited to the listed at-risk and affected counts and serious-event terms. Group-specific death counts are not reported in the registry record; the deaths fields are null. The basis of the serious-event percentages, event timing, exposure, and attribution are not described. These limitations mean the safety entries cannot support a detailed comparative assessment.

The registry identifies no analyses overall. It is not possible to determine from the posted record whether additional results were collected but not entered, or whether no further analyses were completed. Either explanation would be speculation. The record supports describing the intended design and the limited posted counts, but not filling in absent results or methodological details.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: UARK 2006-15: A Study of Tandem Transplants With or Without Bortezomib and Thalidomide — NCT00574080.
• Registry record last updated 2017-11-20; status last verified 2017-10.
• Results first posted 2011-06-30.
• 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

NCT00574080 is a randomized, parallel-group Phase III study sponsored by the University of Arkansas, with no masking, in multiple myeloma. Arm A used DPACE induction and consolidation with the described tandem transplant and dexamethasone maintenance regimen. Arm B added VTD to the transplant treatment phases. The registry lists enrollment of 20, a start of 2006-07, primary completion of 2011-03, and status as terminated.

The primary outcome was event-free survival, measured from study registration until disease progression or death, with a timeframe of up to 3 years 8 months. The registry reports no analysis of this endpoint and no analyses overall. Its primary outcome note states that participants either died or were withdrawn by the principal investigator and that termination occurred with <10% of target accrual enrolled.

Safety entries list serious and other adverse-event counts by group and serious-event terms, but do not provide a comparative safety analysis or group-specific death counts. The registry does not report the reason for termination or key analysis details. The intended treatment contrast is clear; the primary outcome result is not available in the registry record.