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 Fludarabine and Busulfan vs. Fludarabine, Busulfan and Total Body Irradiation (NCT01366612), a randomized phase 3 study. The primary outcome is To Compare the Relapse Rate at 1 Year of Patients With Myeloid Malignancies Receiving Each Treatment.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01366612 |
| Phase | Phase 3 |
| Condition | Myeloid Malignancies, Acute Myelogenous Leukemia, Chronic Myelogenous Leukemia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 53 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Hackensack Meridian Health |
| Results posted | Yes |
2. Clinical Question
Population
Patients with myeloid malignancies who were eligible for allogeneic hematopoietic stem cell transplantation. The registry lists acute myelogenous leukemia, chronic myelogenous leukemia, myeloproliferative disorders, and myelodysplastic syndrome among the conditions of interest. The primary outcome description specifies that the relapse rate was analyzed in 34 patients with AML.
Intervention
Fludarabine and busulfan followed by low-dose total body irradiation. The registry describes this as a conditioning regimen for patients receiving an allogeneic stem cell transplant.
Comparator
Fludarabine and busulfan without the addition of low-dose total body irradiation. This is identified as Group 1, while the regimen including irradiation is Group 2.
Primary question
To compare the relapse rate at 1 year between patients with myeloid malignancies receiving each treatment. The posted outcome concerns patients with AML, and the registry reports the rate separately for the two groups. It does not report a statistical test or an estimate of the uncertainty around the difference between groups.
The study was designed as a randomized comparison of conditioning regimens in people undergoing allogeneic transplantation. Its clinical question concerns whether the addition of low-dose total body irradiation is associated with a different one-year relapse rate in this setting. Relapse is an outcome of interest because it captures return or progression of the underlying disease after transplantation, while the trial description also identifies transplant-related toxicity as something to assess during follow-up.
The registry’s primary outcome is narrower than the full range of conditions listed for the study: its population note says relapse was analyzed in patients with AML. The reported arm counts for that outcome are 18 and 16. Those counts should be understood as the populations represented in the posted relapse results, not automatically as the number randomized to each arm or the total number enrolled.
3. Trial Design
This was a phase III, randomized, parallel-group study with no masking reported. Participants were assigned to one of two conditioning regimens before allogeneic hematopoietic stem cell transplantation: fludarabine and busulfan, or fludarabine and busulfan with low-dose total body irradiation. The registry describes the study as single institution and identifies Hackensack Meridian Health as the sponsor.
The study description states that 80 subjects were planned for enrollment at The John Theurer Cancer Center at Hackensack University Medical Center. The registry’s enrollment figure is 53. The record does not explain the difference between the planned and recorded enrollment, and the study status is terminated. A reason for termination is not reported in the registry record.
The registry lists a study start of 2010-06-16 and a primary completion date of 2020-08-17. These dates describe the registered study timeline; they do not establish when each participant was enrolled, treated, or followed. The brief description says participants would be followed until 1 year after transplantation to assess relapse and transplant-related toxicity.
The random assignment and parallel design support a treatment-group comparison in principle. However, the registry does not report details such as the randomization procedure, allocation ratio, concealment, masking of outcome assessment, or the timing and conduct of any interim analyses. These design details should not be inferred from the phase or from the fact that the trial was randomized. The registry also does not report a protocol or a detailed statistical analysis plan.
For the primary relapse outcome, the record reports results for 34 patients with AML. It separately records safety populations of 25 and 22 participants at risk in the two groups. The available descriptions do not explain how participants entered these outcome populations or how they relate to the total enrollment. The distinction matters: the enrollment figure, primary-outcome group counts, and safety denominators refer to different reported quantities and should not be treated as interchangeable.
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: Of the 53 consented, Forty-Seven patients with myeloid diseases were randomized into Flu/Bu4 (25 patients) or Flu/Bu4/TBI (22 patients)
Overall Study
| Stage | Group 1 | Group 2 |
|---|---|---|
| STARTED | 25 | 22 |
| COMPLETED | 25 | 22 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Relapse Rate was analyzed in 34 patients with AML
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: Of the 53 consented, Forty-Seven patients with myeloid diseases were randomized into Flu/Bu4 (25 patients) or Flu/Bu4/TBI (22 patients)
| Characteristic | Unit | Group 1 | Group 2 | Total |
|---|---|---|---|---|
| Participants analysed | 25 | 22 | 47 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 25 | 22 | 47 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | Years | 48.4 (23 to 62) | 48.8 (22 to 63) | 48.6 (22 to 63) |
| Sex: Female, Male: Female | Participants | 11 | 8 | 19 |
| Sex: Female, Male: Male | Participants | 14 | 14 | 28 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 3 | 3 | 6 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 21 | 19 | 40 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 3 | 0 | 3 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 2 | 3 |
| Race (NIH/OMB): White | Participants | 18 | 19 | 37 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 3 | 1 | 4 |
| Region of Enrollment: United States | participants | 25 | 22 | 47 |
6. Primary Endpoint
The registry lists the primary outcome as To Compare the Relapse Rate at 1 Year of Patients With Myeloid Malignancies Receiving Each Treatment, measured over 1 year.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percent |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the relapse rate at 1 year among patients with myeloid malignancies receiving each conditioning regimen. Relapse is a clinically relevant outcome in a transplantation study because the treatment comparison concerns disease control after transplantation. The registry’s outcome description specifies that the posted relapse analysis involved patients with AML, even though the study conditions also include other myeloid malignancies.
The outcome is recorded as a percentage, with the reported value representing the relapse rate for each group. Group 1, which received fludarabine and busulfan, has a reported value of 38.9%. Group 2, which also received low-dose total body irradiation, has a reported value of 18.8%. The corresponding group counts for this outcome are 18 and 16, respectively. No confidence interval or formal between-group test is reported.
A fixed follow-up horizon can make outcome summaries easier to interpret by relating them to the same stated time point. In general, however, a rate at a specified time needs a clear definition of the outcome, the population included, and the handling of participants whose outcome status is unavailable. Those details are not fully described for this endpoint in the registry record. The record does not say whether the percentages are based on a time-to-event method or a direct proportion, nor does it give a detailed definition of relapse for this analysis.
The brief study description also mentions transplant-related toxicity, but that does not change the registered primary endpoint. The primary outcome reported is relapse at 1 year, and the posted result should be interpreted as a descriptive summary for the specified AML analysis population.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary-outcome values are 38.9% for Group 1 and 18.8% for Group 2. Group 1 received fludarabine and busulfan; Group 2 received those agents with low-dose total body irradiation. Thus, the reported relapse rate is lower in the group whose regimen included irradiation. This is a descriptive comparison of the values in the registry, not evidence by itself that the observed difference is statistically reliable or attributable to the additional treatment.
The outcome population is described as 34 patients with AML, with group counts of 18 and 16. The registry does not report a confidence interval, standard error, p-value, adjusted estimate, or formal test for the treatment comparison. Without an estimate of uncertainty, readers cannot judge how precisely the group values estimate the underlying rates or how compatible the results are with a range of possible treatment effects. The registry also does not report enough detail to determine the method used to calculate the one-year rates.
The result should be kept distinct from the overall enrollment figure of 53 and from the safety populations. The primary outcome population is specifically described as patients with AML, whereas the study was intended to include a broader set of myeloid malignancies. The record does not explain why the outcome population is restricted to AML or how the remaining enrolled participants contributed to outcome analyses. It also does not report whether all participants had complete follow-up through the stated time point.
The treatment arms were randomized, which is relevant to the design of a comparative study, but randomization alone does not supply the missing analysis details. The method of allocation, analysis population, handling of missing outcomes, and any covariate adjustment are not reported in the registry record. These features affect how a treatment contrast should be estimated and interpreted.
The result therefore supports a limited reading: the registry posts two one-year relapse-rate values, and the value for the regimen including low-dose total body irradiation is lower. The result does not establish the size or precision of a causal treatment effect, demonstrate statistical significance, or settle whether the groups differed beyond chance variation. The sponsor’s analysis is not reported, and there is no basis in the registry record for replacing the posted values with a recalculated inferential comparison.
The trial status is terminated, and the recorded enrollment is 53 compared with a planned enrollment of 80 described in the study summary. The record gives no reason for termination and no sample-size justification. Those gaps limit assessment of whether the observed outcome population and available follow-up were adequate for the planned comparison. They do not change the descriptive values, but they constrain what can be concluded from them.
9. Statistical Methods Explained
The registry identifies a randomized, parallel-group, phase III trial. Randomization is a design method intended to make treatment groups comparable in expectation with respect to factors known and unknown at assignment. In general, randomization does not guarantee that every characteristic will be balanced in a particular trial, especially when the groups are small. The registry does not report the sequence-generation procedure, allocation concealment, or any stratification factors, so those aspects of the method cannot be assessed from this record.
What does the reported rate describe?
The primary outcome is relapse at 1 year, reported as a percentage. The posted values are 38.9% for Group 1 and 18.8% for Group 2. The outcome description says the analysis involved 34 patients with AML, and the arm counts are 18 and 16. The registry does not provide a formula for the rate or state whether a time-to-event estimator was used. In general, a simple proportion and a time-to-event estimate can differ when follow-up varies or when participants are censored, so knowing the calculation method is important to interpreting a fixed-time outcome.
The outcome description identifies a follow-up horizon but does not define the relapse event in detail, state how competing events were handled, or describe whether the analysis included all randomized participants. These details are not reported in the registry record. They should not be inferred from the use of the word rate or from the stated timeframe.
How should uncertainty be assessed?
A confidence interval is a statistical range reflecting uncertainty in an estimated quantity under a specified method. In general, intervals communicate both the direction and the precision of an estimate; a narrow interval indicates greater precision than a wide one. The registry does not report confidence intervals for the relapse rates or for a treatment contrast. As a result, the precision of the reported values and the uncertainty around the difference between groups cannot be evaluated from the posted outcome alone.
A hypothesis test can assess how compatible observed data are with a specified null hypothesis under a statistical model. A p-value is not a measure of the probability that a treatment works, and it does not describe the size or clinical importance of an effect. No p-value or test result for the primary comparison is reported. The record lists no posted analyses, and the endpoint is classified as a count outcome that is not reduced to one comparison. A formal analysis cannot be reconstructed reliably from the summary values alone.
Why can a count outcome require special care?
Counts and rates can have distributions that differ from the assumptions of simple comparison methods. In general, over-dispersion occurs when the observed variability in count data exceeds what a chosen model assumes. If present, it can make standard errors too small and confidence intervals too narrow unless the analysis accounts for it. The registry does not identify a count model, report a dispersion estimate, or describe whether over-dispersion was assessed. This general issue is relevant to count outcomes, but the record does not establish that over-dispersion occurred in this trial.
The registered result is expressed as a percentage, but the registry also classifies the endpoint as a count outcome and does not provide a model or analysis details. Those entries do not reveal how the result was derived. The reported arm values should therefore be read as posted summaries, not as a fully specified model-based analysis.
What can planning illustrations tell readers?
Planning calculations can illustrate the number of participants that a future study might need under stated assumptions. In general, such calculations depend on a target effect, a significance level, allocation, and a statistical approximation. They are not measures of the probability that a completed study detected an effect. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. The calculations are planning illustrations rather than the trial’s own design justification, and they should not be described as observed power.
The registry does not report the original sample-size justification or the assumptions used to set planned enrollment. The planned enrollment of 80 appears in the study summary, while the recorded enrollment is 53. The record does not explain that difference or show whether the trial’s original design assumptions were revised. Planning scenarios based on an observed effect cannot fill that gap: they answer a different question from whether the original trial was designed adequately.
What analysis details are unavailable?
The registry does not report an adjusted analysis, subgroup analysis, interim analysis plan, statistical software, or a detailed protocol-defined analysis population. It also does not report how missing outcomes, withdrawals, or censoring were handled. These omissions prevent a detailed appraisal of model choice, assumptions, and the robustness of the reported comparison. General statistical principles can identify why these details matter, but they cannot supply trial-specific methods that are absent from the registry.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure and no posted secondary outcomes. It does not report a multiplicity plan or say whether any additional outcomes, subgroups, or interim looks were tested. When multiple hypotheses are examined, the chance of at least one apparently notable result can increase; statistical plans commonly address this issue by defining the primary comparison and specifying any adjustment or hierarchy. This is a general consideration, not evidence that multiple testing occurred in this trial.
The primary-outcome population is described as 34 patients with AML, with 18 in Group 1 and 16 in Group 2. The total enrollment is 53, and the study conditions include malignancies beyond AML. The registry does not explain the eligibility of the outcome population, why the posted analysis is limited to AML, or how participants outside that outcome population were handled. It does not state whether the primary analysis followed an intention-to-treat principle or another analysis-population definition.
Missing outcome data can affect estimates when participants lack the information needed to determine their status at the stated follow-up time. In general, the impact depends on the amount and pattern of missingness and on the analysis method. The registry does not report missing-data counts, reasons for missingness, follow-up completeness, imputation methods, or sensitivity analyses. It is therefore not possible to assess from this record whether missing data influenced the reported relapse rates.
The registry also does not report a prespecified statistical analysis plan, interim analyses, or adjustments for multiple comparisons. Their absence from the record should not be interpreted as proof that these activities did not occur; their details are not reported in the registry record.
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 |
|---|---|---|---|
| Group 1 | 18 | 25 | 72.0% |
| Group 2 | 16 | 22 | 72.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Group 1 | 6 of 25 |
| Group 2 | 8 of 22 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Group 1 | 0 of 25 |
| Group 2 | 0 of 22 |
Most frequent serious adverse event terms
| Event term | Organ system | Group 1 | Group 2 |
|---|---|---|---|
| GvHD | Immune system disorders | 9 of 25 | 6 of 22 |
| Relapse/Disease Progression | Investigations | 7 of 25 | 5 of 22 |
| Infection/Reactivation | Infections and infestations | 5 of 25 | 2 of 22 |
| Pneumonia | Respiratory, thoracic and mediastinal disorders | 3 of 25 | 2 of 22 |
| BK hemorrhagic cystitis | Infections and infestations | 0 of 25 | 4 of 22 |
| Fever | Investigations | 1 of 25 | 2 of 22 |
| Multi-system failure | Investigations | 1 of 25 | 2 of 22 |
| Shortness of Breath | Respiratory, thoracic and mediastinal disorders | 1 of 25 | 2 of 22 |
| Bowel Obstruction | Gastrointestinal disorders | 0 of 25 | 2 of 22 |
| Cardiac Tamponade | Cardiac disorders | 0 of 25 | 1 of 22 |
Serious events with the highest arm-level rate: gvhd (36.0%), relapse/disease progression (28.0%), infection/reactivation (20.0%), bk hemorrhagic cystitis (18.2%), pneumonia (12.0%).
The safety record lists 25 participants at risk in Group 1 and 22 in Group 2. Serious adverse events affected 18 participants in Group 1 and 16 in Group 2. Other adverse events affected 0 participants in either group, using the registry’s separate other-event fields. Deaths are recorded as 6 in Group 1 and 8 in Group 2.
These figures are counts, not treatment-effect estimates. The safety denominators differ from the primary relapse-outcome counts of 18 and 16, and the registry does not explain the relationship between these populations. It also does not specify in the safety summary the observation period, whether each participant could contribute more than one event, or whether the deaths were judged related to treatment, transplantation, or the underlying disease. The counts therefore should not be used to infer comparative risk or causation.
The registry lists serious-event terms and percentages, including GvHD at 36.0%, Relapse/Disease Progression at 28.0%, Infection/Reactivation at 20.0%, BK hemorrhagic cystitis at 18.2%, Pneumonia at 12.0%, and Fever at 9.1%. The denominator and calculation details for these term percentages are not reported in the registry record. The listed terms describe events recorded in the safety data; they do not establish that the treatment caused them or that their frequencies differ between arms.
12. What the Result Does, and Does Not, Mean
The registry’s primary outcome gives a descriptive one-year relapse rate of 38.9% for the fludarabine-and-busulfan group and 18.8% for the group receiving those agents with low-dose total body irradiation. The results are reported for 34 patients with AML. These values show that the posted rate is lower in Group 2, but they do not quantify the uncertainty around that contrast.
The record does not report a confidence interval, p-value, adjusted comparison, or formal test. Without those results, the observed ordering of the group values cannot be distinguished from a difference that may reflect sampling variability. The registry also does not state how the rate was calculated, how missing follow-up was handled, or whether the analysis included all randomized participants. These are important qualifications for a time-specific outcome.
The study was randomized, but the registry does not provide enough information to assess the randomization procedure or the analysis methods in detail. The outcome population is specifically described as patients with AML, while the study conditions encompass other myeloid malignancies. The record does not explain how that narrower population relates to the full study enrollment. This limits how broadly the result can be applied even as a description of the trial.
The result does not establish that either regimen is superior, that the addition of irradiation caused the difference in the posted values, or that a treatment effect is clinically important. It also does not establish that the groups were equivalent. A failure to report an inferential comparison is not evidence that no difference exists; it means the registry record does not provide the analysis needed to evaluate that question.
Safety information should be considered separately. The registry lists serious adverse event counts, other adverse event counts, deaths, and selected event terms, but the summary does not clarify the event windows, term denominators, or causal attribution. These data provide a record of reported events, not a complete comparative safety analysis.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized comparison with a clinically focused endpoint and a clearly stated follow-up horizon. The primary question concerns relapse at 1 year after transplantation, a fixed-time outcome that is readily understood in clinical terms. The two posted arm values allow readers to describe the direction of the observed difference, while the absence of inferential results illustrates why a point estimate alone is not enough for a comparative conclusion.
The record also illustrates the importance of keeping analysis populations distinct. It reports total enrollment of 53, primary relapse counts of 18 and 16 among patients with AML, and safety denominators of 25 and 22. These quantities describe different populations or outcome records, and the registry does not explain how they relate. Treating them as interchangeable could lead to an inaccurate account of who contributed to each result.
There is also a gap between the planned enrollment of 80 described in the study summary and the recorded enrollment of 53. The record is marked terminated, but the reason is not reported. These registry entries matter when considering precision and completeness, yet they do not reveal why enrollment ended or what statistical consequences followed. Those explanations cannot be reconstructed from the posted summary.
Finally, the trial emphasizes the value of a prespecified, accessible analysis plan. Details on the rate calculation, missing data, analysis population, uncertainty estimates, and multiplicity would help readers assess the strength and scope of the evidence. Their absence does not erase the reported outcome values, but it limits the conclusions that can be drawn from them.
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 primary result is confined to the AML population specified in the outcome description, although the study includes several types of myeloid malignancy. The registry does not explain why the analysis is restricted to AML or how the other conditions contributed to the study. Generalization beyond the population represented by the posted outcome should therefore be cautious.
The recorded enrollment is 53, while the study summary describes a planned enrollment of 80. The registry status is terminated, and no reason for termination is reported in the registry record. The record does not state whether recruitment stopped early, whether the enrollment target changed, or whether follow-up was complete. It is not possible to infer the cause or its effect on the result.
The primary result lacks an inferential comparison and uncertainty estimates. No confidence interval, p-value, model, or adjusted estimate is reported. The registry does not describe the calculation of the one-year rate, the handling of competing events, or the treatment of missing outcomes and censoring. Consequently, precision and sensitivity to analytic choices cannot be evaluated.
The available population counts differ across the primary outcome and safety summaries, and their relationship to the overall enrollment is not explained. The safety information also lacks detail on observation periods, event-term denominators, and attribution. The record does not report the randomization procedure, allocation concealment, outcome-assessment masking, or a detailed statistical analysis plan. These limitations are specific to the information recorded for this trial and constrain interpretation without changing the values that are posted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Fludarabine and Busulfan vs. Fludarabine, Busulfan and Total Body Irradiation — NCT01366612.
- Registry record last updated 2026-04-03; status last verified 2026-03.
- Results first posted 2022-12-16.
- 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
NCT01366612 is a phase III randomized, parallel-group study comparing fludarabine and busulfan with fludarabine, busulfan, and low-dose total body irradiation before allogeneic hematopoietic stem cell transplantation. The registry describes a single-institution study sponsored by Hackensack Meridian Health, with a planned enrollment of 80 and recorded enrollment of 53. Its status is terminated.
The primary outcome is relapse rate at 1 year. The registry says the analysis involved 34 patients with AML and reports 38.9% for Group 1 and 18.8% for Group 2. It does not report a formal treatment comparison, confidence intervals, or a p-value. Safety counts are recorded separately, with denominators of 25 and 22 at risk.
The record lists a study start of 2010-06-16 and a primary completion date of 2020-08-17. The reason for termination, the original sample-size justification, and detailed analysis methods are not reported in the registry record.