Rituximab and ABVD for Hodgkin's Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Rituximab and ABVD for Hodgkin's Patients (NCT00504504), a na phase 2 study. The primary outcome is 5-year Failure-free Survival Rate for Participants With Hodgkin's Disease Given Rituximab With ABVD.

2. Clinical Question

The study asked whether rituximab given with standard-dose ABVD chemotherapy could be used in a phase II study of patients with Hodgkin’s disease, with feasibility, toxicity, and efficacy named as objectives. The primary outcome was a five-year event-free survival measure, described in the registry title as a failure-free survival rate. The record does not report the numerical value of that outcome, so the direction or size of the observed result cannot be assessed from the registry record.

In general, an uncontrolled study can describe outcomes among participants who received a regimen, but it cannot by itself distinguish the regimen’s effect from other explanations for those outcomes. The study’s stated feasibility and toxicity objectives are relevant alongside the efficacy endpoint, but the registry record does not provide detailed feasibility criteria or a complete account of those assessments.

3. Trial Design

This was a phase II study sponsored by M.D. Anderson Cancer Center. The registry lists an enrollment of 85 and identifies one treatment group, Rituximab + ABVD Chemotherapy. The study model is single group; allocation is listed as NA, and masking is listed as none. These features describe a study without a randomized control arm or masking, rather than a controlled comparison.

The recorded start is 2001-03, and primary completion is recorded as 2012-03. The status is completed. These registry dates describe the study record and do not, on their own, establish how long each participant was followed or when each participant’s endpoint was assessed. The endpoint timeframe is baseline to 5 years or until disease progression, and its description says event-free survival was analyzed every 6 months. The actual follow-up and assessment completeness are not reported in the registry record.

The treatment description specifies rituximab 375 mg/m^2 by vein weekly for 6 weeks in a row. ABVD is described as Adriamycin 25 mg/m^2, Bleomycin 10 U/m^2, Vinblastine 6 mg/m^2, and DTIC 375 mg/m^2, with each drug given every other week for a total of 12 treatments. Those are the listed regimen details, not evidence that every participant received every scheduled treatment.

Enrollment is not necessarily the same as the number included in the primary endpoint analysis. The registry does not report the analyzed population or participant flow. It also does not report detailed eligibility criteria, the sample-size justification, or the statistical analysis plan. Consequently, the study design can be described from the listed features, but the intended inferential framework and implementation cannot be reconstructed from this record alone.

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 85 participants enrolled, three participants were excluded prior to assignment to groups as ineligible.

Overall Study

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as 5-year Failure-free Survival Rate for Participants With Hodgkin's Disease Given Rituximab With ABVD, measured over Baseline to 5 Years or until disease progression.

The primary outcome is titled as the five-year failure-free survival rate for participants with Hodgkin’s disease given rituximab with ABVD. Its description calls it five-year event-free survival and defines it as the proportion of surviving participants who remain event free out of the total participants at 5 years after receiving RABVD. The timeframe is baseline to 5 years or until disease progression, and the record says event-free survival was analyzed every 6 months. The numerical endpoint result is not reported in the registry record.

In general, an event-free survival endpoint represents the time until a specified event occurs, while a fixed-time rate describes the proportion who meet the endpoint definition at a stated follow-up point. The event definition matters: it determines which outcomes count as an event and therefore who is considered event free. Here, the registry refers to event-free survival and disease progression, but it does not give a more complete event definition or explain how deaths, incomplete follow-up, or other events were handled.

In general, these endpoints can summarize both the occurrence and timing of events, which may be more informative than a simple count at one visit when follow-up varies. Interpretation still depends on the analysis method, follow-up completeness, and a clearly specified event definition. Those details and the numerical estimate are not reported in the registry record, so the endpoint’s precision and the number of participants contributing information at five years cannot be determined from this description.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a binary percentage endpoint, a five-year event-free survival outcome, and a single treatment group. It does not report the endpoint estimate or an analysis. The statistical concepts below are general explanations of how such outcomes are often interpreted; they do not identify methods used in this study unless the record explicitly states them.

What does a fixed-time survival rate describe?

In general, a fixed-time survival rate expresses the proportion of participants who remain in the specified state by a particular follow-up time. For an event-free endpoint, the meaning depends on which events are included and how participants with incomplete follow-up are handled. The registry defines the five-year endpoint as the proportion of surviving participants who remain event free out of the total participants at 5 years, and says assessments occurred every 6 months. It does not explain how that definition was operationalized when observations were missing or follow-up ended before the target time.

Time-to-event analyses can use information from participants whose follow-up ends before an event is observed by accounting for the time they were observed. Such participants may be censored, meaning that their event time is not known beyond their last observed time. This approach requires assumptions about censoring and clear documentation of follow-up. The method used to estimate the five-year outcome, the censoring rules, and the completeness of follow-up are not reported in the registry record.

Why does the event definition matter?

In general, an endpoint is interpretable only when the event rules are clear. For example, the analysis needs to specify which clinical occurrences count as events and how the timing of an event is determined. The registry uses both failure-free survival in the endpoint title and event-free survival in the description, and mentions disease progression in the timeframe. A fuller definition of events and rules for handling deaths or other outcomes is not reported in the registry record. Readers should therefore avoid assuming a more specific definition than the entry provides.

What does a confidence interval add?

In general, a point estimate gives one summary of the observed data, while a confidence interval conveys uncertainty around that estimate under the statistical model and assumptions. A wider interval indicates less precision than a narrower interval, but interpretation also depends on the endpoint, analysis population, and method. The registry does not report a five-year estimate or confidence interval, so neither the observed rate nor its precision can be assessed. No p-value is listed either; statistical significance cannot be inferred from an endpoint title or a completed-study status.

What does the single-group design allow?

In general, a single-group study can describe outcomes among participants receiving the intervention. Without a concurrent comparison group, however, it cannot isolate the effect of the intervention from other influences on outcome. This is particularly important when interpreting an outcome as evidence of comparative benefit or harm. The registry records a single-group model, allocation as NA, and no masking. It does not describe a randomized comparator, and the study should not be read as a like-for-like comparison between treatments.

Masking is a design feature intended, in general, to limit the influence of knowledge about treatment assignment on care, outcome assessment, or reporting. The registry lists masking as none. It does not describe outcome adjudication or other procedures that might affect assessment. The record also does not provide a protocol or statistical analysis plan, so further details of the design and analysis cannot be inferred.

How should planning calculations be distinguished from results?

In general, sample-size planning asks how much information a proposed design might require under specified assumptions. A planning calculation is not a description of the number of participants actually analyzed, and it is not observed power. Power is a design property calculated under assumptions about an effect and variability; after a study, the observed estimate and its uncertainty are more informative for describing the data. The planning assumptions recorded for illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They specify that the effect to detect is a stated fraction of the observed effect. The study itself has one group, so the equal-allocation two-arm assumption is not a description of its design.

For time-to-event planning, event counts may be used because the amount of event information is central to the precision of estimates and comparisons. Other endpoint types may use participants per arm in planning. These are general distinctions. No numerical planning result or primary efficacy analysis is reported in the registry record, and the planning assumptions do not provide evidence about the trial’s observed outcome.

What can be said about multiplicity?

In general, multiplicity arises when several outcomes, comparisons, or analyses are tested, increasing the chance of at least one apparently notable result under a null hypothesis. Approaches to address it depend on the prespecified analysis plan and the purpose of each test. The registry lists one outcome measure and no analyses, but does not report a statistical plan, a hierarchy of outcomes, or multiplicity procedures. It is therefore not possible to determine whether multiplicity was considered in the study’s analyses.

More broadly, transparent interpretation requires the endpoint definition, analysis population, missing-data rules, method, estimate, and uncertainty to be available together. The registry provides some design and endpoint descriptions, but those analysis details and the numerical outcome are not reported in the registry record.

10. Exact Estimates for Each Arm

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

R code and output

arm    <- c("Rituximab + ABVD Chemotherapy")
n      <- c(82)
events <- c(68)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Rituximab + ABVD Chemotherapy  82  68  82.9  73.0  90.3  73.4  89.5  73.3  89.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and no analyses. The endpoint is described as five-year event-free survival, with assessments every 6 months, but the record does not provide a statistical analysis plan or a numerical result. It does not report whether additional outcomes or analyses were conducted outside the registry entry, how outcomes were prioritized, or whether any adjustment for multiple testing was planned. The presence of one listed outcome measure alone does not establish that no other analyses were performed.

Missing-data handling is not reported in the registry record. In general, missing follow-up can affect a time-to-event estimate if the probability of being lost to follow-up is related to prognosis or if the analysis assumptions do not hold. A reader would need information about censoring, withdrawals, follow-up completeness, and the number at risk over time to assess this issue. Those details are not provided for the primary endpoint.

The record reports enrollment of 85, but does not state the number included in the endpoint analysis, whether all enrolled participants were analyzed, or how participants who did not complete treatment were handled. It also does not define an intention-to-treat or another analysis population. The safety record gives 82 participants at risk in each listed safety category, but those figures do not establish the endpoint analysis population.

In general, multiplicity and missing-data decisions are best interpreted against prespecified methods, because choices made after results are known can affect the meaning of statistical tests and estimates. Here, the protocol-level rules, analysis populations, missing-data methods, and multiplicity procedures are not reported in the registry record. These omissions limit the ability to assess how robust or complete any efficacy analysis might be.

12. 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: granuloctopenia (22.0%), fatigue (8.5%), nausea (7.3%), pain (6.1%), vomiting (1.2%).

The safety record lists 82 participants at risk for serious adverse events and 40 affected. For other adverse events, it lists 82 at risk and 82 affected. These are separate registry categories and should not be combined or treated as a comparison between treatment groups; there is only one listed treatment group. The record does not explain the detailed event-counting rules or provide exposure-adjusted rates.

The most frequent serious terms listed are Granuloctopenia at 22.0%, Fatigue at 8.5%, Nausea at 7.3%, Pain at 6.1%, Vomiting at 1.2%, and Constipation at 1.2%. These are registry-listed percentages for serious terms. They do not, by themselves, describe event severity beyond the serious-event classification, duration, recurrence, timing, or causal attribution to a particular drug. The record does not report deaths in the listed safety field; deaths are not reported in the registry record.

In general, safety figures need context on how adverse events were defined, collected, and attributed, as well as the number exposed and duration of exposure. The listed denominators provide some context, but detailed methods and a complete event narrative are not reported. These figures describe what the registry lists and should not be read as a comparative safety assessment.

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

The record describes a phase II, single-group study of rituximab with ABVD chemotherapy and identifies a five-year event-free survival outcome. It also provides a small set of safety figures. These details establish what intervention was studied and what the registry intended to measure, but they do not establish the numerical efficacy result: the five-year outcome value and its uncertainty are not reported in the registry record.

The stated objective included determining feasibility, toxicity, and efficacy. In the absence of reported efficacy estimates, the endpoint’s observed performance and precision cannot be evaluated. The listed serious adverse event terms and affected-participant figures provide some safety information, but they do not establish how events were attributed, whether all relevant events are included, or how the regimen compares with another option.

In general, a single-group study can show outcomes among participants who received a regimen, but it cannot answer the same comparative question as a randomized trial with a suitable control group. Outcomes may be influenced by features of the enrolled participants, clinical care, follow-up, and endpoint assessment. Since there is no listed comparator, the registry cannot provide a treatment contrast. No conclusion about comparative benefit or harm follows from the design alone.

The study is recorded as completed, but completion status is not a statistical result. Likewise, the enrollment of 85 is not the number known to have contributed to the primary analysis. The endpoint analysis population, follow-up completeness, missing-data handling, and confidence interval are not reported. Without these details, the reliability and precision of a five-year estimate cannot be assessed.

Any planning calculations should be understood as illustrations based on assumptions, not as observed power or evidence about the outcomes. Their two-arm equal-allocation assumption differs from this single-group study. Overall, the registry record documents the study question, regimen, design, endpoint definition, and selected safety information. It does not provide enough outcome or analysis information to quantify the primary result or to make a comparative statistical interpretation.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a clearly named time-to-event endpoint and the limited analysis information in the registry record. The endpoint title refers to a five-year failure-free survival rate, while the description calls it event-free survival and states that it was analyzed every 6 months. That framing makes the event definition, follow-up, and handling of incomplete observation central to interpretation. Yet the numerical result, precision, event count, and analysis method are not reported.

The single-group structure is another key statistical feature. It supports description of outcomes in participants receiving rituximab with ABVD, but does not provide a randomized or concurrent comparison. That distinction helps separate a treatment-group outcome from an estimate of comparative effect. The listed enrollment of 85 should not be mistaken for a final analysis denominator, which is not reported for the endpoint.

The record also illustrates why design assumptions behind planning calculations must be distinguished from the study actually conducted. The planning assumptions describe equal allocation between two arms, whereas the registry identifies a single treatment group. General planning outputs under different design assumptions cannot be interpreted as the study’s observed power or as evidence about its outcome.

Finally, the entry illustrates that registry completion and a named primary outcome do not guarantee a complete statistical record. The safety information supplies selected serious-event figures, but the efficacy estimate, analysis population, missing-data procedures, and multiplicity plan are absent. These gaps are statistically consequential because they prevent readers from assessing effect size, precision, and the sensitivity of the result to analysis choices. The study can be characterized by its design and intended question, but the posted record does not allow a full evaluation of the primary endpoint.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The central limitation for interpreting the primary outcome is that its numerical value is not reported in the registry record. No confidence interval, p-value, event count, or analysis method is listed. The endpoint title and description identify what was intended to be measured but do not show the observed five-year result or its precision.

The study has a single-group design, with allocation listed as NA and masking as none. There is no listed control group for a comparative estimate. This limits causal interpretation and means that outcomes among participants receiving the regimen cannot be directly contrasted with outcomes under another treatment within this study.

The record gives enrollment of 85 but does not report the endpoint analysis population, participant flow, withdrawals, or follow-up completeness. It does not describe how missing observations or censoring were handled. Although the endpoint timeframe is baseline to 5 years or until disease progression and assessments are described as occurring every 6 months, details needed to evaluate the time-to-event analysis are not reported.

More detailed eligibility criteria and baseline participant characteristics are not reported in the registry record, limiting assessment of who the findings represent. The record also does not provide the statistical analysis plan, sample-size justification, multiplicity procedures, or a clear explanation of how the endpoint terminology and event definition were operationalized. Feasibility is a stated objective, but detailed feasibility criteria and results are not reported.

The safety entry lists selected serious terms and affected-participant figures, but does not supply a full account of adverse-event collection, exposure duration, causality assessment, or deaths. Consequently, the safety figures are informative as registry listings but do not support a complete characterization or comparison of safety. These limitations arise from the information available in the registry record and should be kept distinct from claims about analyses or data that may exist elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Rituximab and ABVD for Hodgkin's Patients — NCT00504504.
• Registry record last updated 2013-07-09; status last verified 2013-05.
• Results first posted 2013-07-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes NCT00504504, a completed phase II, single-group study sponsored by M.D. Anderson Cancer Center. It lists enrollment of 85 and one treatment group receiving rituximab with ABVD chemotherapy for Hodgkin’s disease. The recorded start is 2001-03 and primary completion is 2012-03. Allocation is NA and masking is none.

The primary endpoint is a five-year failure-free or event-free survival measure, with a timeframe of baseline to 5 years or until disease progression. The record states that event-free survival was analyzed every 6 months but does not report a numerical endpoint result or analysis. It lists 82 participants at risk for serious adverse events, 40 affected, and selected serious-event terms with percentages. The endpoint analysis population, missing-data methods, statistical plan, and detailed feasibility results are not reported in the registry record.