A Study of MabThera (Rituximab) in Elderly Patients With Untreated Follicular Non-Hodgkin's Lymphoma (NHL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of MabThera (Rituximab) in Elderly Patients With Untreated Follicular Non-Hodgkin's Lymphoma (NHL) (NCT01144364), a na phase 3 study. The primary outcome is Percentage of Participants With Disease Progression or Death.

2. Clinical Question

The study's stated clinical question concerns outcomes after a brief induction course and the subsequent maintenance strategy. Its title frames the question as a comparison between rituximab maintenance and no further therapy. That framing alone does not establish that the registry record supports a valid treatment comparison: its design fields identify a single-group model and no allocation information, and its own caution says the groups are not a like-for-like control comparison.

The record describes progression-free survival from randomization as the primary measure. It defines this as time from randomization until documented progression, relapse, or death from any cause. The primary measure is expressed as a percentage of participants with progression or death, with estimates specified for 12, 24, and 34 months. The actual estimates, event counts for this endpoint, and uncertainty intervals are not reported in the registry record. The clinical question can therefore be described, but the size and precision of the observed primary outcome cannot be assessed from these details.

3. Trial Design

The registry identifies this as a Phase 3, open-label study with no masking. It lists 234 participants as enrolled, and its model field describes a single-group study. Allocation is recorded as NA. Although the official title describes a randomized comparison of maintenance therapy with no further therapy, the registry specifically cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. These design details limit interpretation of any apparent difference between follow-up groups.

The study description concerns brief induction with a chemotherapy regimen containing rituximab, followed by either rituximab maintenance or no further therapy. The listed intervention is rituximab; the arm-description field is blank. Details of the chemotherapy regimen, maintenance schedule, eligibility criteria, and treatment assignment process are not reported in the registry record. The brief summary states that anticipated time on study treatment was 1-2 years and gives a target sample size of 100-500 individuals. The reasoning behind that target is not reported in the registry record.

The primary endpoint is progression-free survival from randomization, with specified time points of 12, 24, and 34 months. The record also lists secondary outcomes concerning progression, disease-free survival, overall survival, response during induction, molecular response, and duration of response. There are 11 outcome measures and 9 analyses listed. Detailed analysis results for these outcomes are not reported in the registry record.

For adverse-event follow-up, the record gives separate group labels for induction and follow-up phases. The induction group lists 233 participants at risk. The maintenance and observation follow-up groups each list 101 at risk. The record does not explain how participants entered those follow-up groups or whether their membership was assigned by a randomized process. The listed group counts should not be treated as evidence of comparable treatment groups.

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.

Induction Phase

Reasons for not completing this period:

Follow-Up/Maintenance Phase

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: ITT population

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: Intention-to-Treat (ITT) population: all participants who were randomized to the maintenance or observation arm. IP population: all enrolled participants who started the induction phase (Months 1-8 of the study)

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Disease Progression or Death, measured over 12, 24, and 34 months.

The primary endpoint is the percentage of participants with disease progression or death, based on progression-free survival from randomization. The registry defines progression-free survival as the time from randomization to documented disease progression, relapse, or death from any cause. It specifies assessment at 12, 24, and 34 months and identifies the intention-to-treat population.

Time-to-event outcomes such as progression-free survival account for both whether an event occurred and how long participants were followed before an event or censoring. This can make the measure useful when participants have different follow-up durations. The registry says the progression-free survival function was estimated with the Kaplan-Meier product-limit method. Participants who responded and participants lost to follow-up were censored at their last assessment date, as described in the record.

In general, censoring means that an event has not been observed by the last known assessment; it does not establish that the participant remained event-free afterward. Kaplan-Meier estimates rely on assumptions about how censoring relates to the chance of the event. The registry record does not report diagnostic checks or further details about those assumptions.

The outcome estimates at the specified time points, event counts, confidence intervals, and p-values are not reported in the registry record. Consequently, the endpoint definition and estimation method are identifiable, but the observed progression-free survival and its precision cannot be evaluated from the record details.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a time-to-event endpoint measure?

Progression-free survival is a time-to-event measure. It considers the time from a defined starting point—in this record, randomization—to the first recorded progression, relapse, or death from any cause. The primary outcome is described as a percentage of participants with progression or death at 12, 24, and 34 months. The registry record does not report the corresponding estimates.

Time-to-event methods are useful when participants may be followed for different lengths of time. A participant who has not experienced an event by the last assessment contributes information up to that point, rather than being treated as if they were followed indefinitely. The method can therefore use incomplete follow-up without pretending that later outcomes are known.

What does Kaplan-Meier estimation do?

The record states that progression-free survival was estimated using the Kaplan-Meier product-limit method. In general, this method estimates the probability of remaining event-free over time, updating the estimate when events occur and accounting for participants whose follow-up ends before an event is observed. It is a descriptive estimator; it does not, on its own, correct for differences between treatment groups or establish a causal effect.

The registry says responding participants and participants lost to follow-up were censored at their last assessment date. Censoring marks the end of observed follow-up without a recorded endpoint event by that date. It is not the same as confirming that no event occurred later. Standard interpretation depends on censoring being sufficiently independent of the event process, conditional on the analysis structure. The record does not report whether that assumption was assessed, or how response-related censoring was handled beyond the stated description.

Why does the design information matter?

A randomized comparison is intended to make treatment groups comparable at the start of follow-up, on average, so that differences in outcomes can be interpreted more credibly. Here, the title describes randomization, but the registry lists allocation as NA and the model as single group. It also cautions that the arms are not a like-for-like control comparison. The randomization procedure, group assignment details, and reasons for the group structure are not reported in the registry record. Accordingly, a difference between the maintenance and observation follow-up counts cannot be interpreted as a randomized treatment effect.

Open-label status means masking is listed as none. In general, knowledge of treatment assignment can affect care, reporting, or outcome assessment, particularly for outcomes that involve judgment. The primary endpoint includes documented progression and relapse, but the registry does not report whether assessors were independent or blinded to treatment. No further conclusions about the impact of open-label conduct can be drawn from the record.

What does the analysis population mean?

The primary endpoint description identifies the ITT population. In general, an intention-to-treat analysis aims to retain participants in the groups to which they were assigned, regardless of subsequent adherence or treatment changes. That principle depends on an assignment process and group definitions that are clear. Because allocation is NA and the record calls the study single group, the operational meaning of ITT in this study is not reported in the registry record. The number included in the primary endpoint analysis and the handling of participants without outcome data are also not reported.

What can be inferred from the reported safety counts?

The registry separately lists participants at risk and participants affected by serious and other events for induction and follow-up. In general, counts should be interpreted with attention to the group definition, time at risk, event definition, and whether participants can have more than one event. The record gives the number affected, but does not report event-level counting rules, exposure durations, or detailed event ascertainment methods. The follow-up groups are not established as randomized comparable groups, so their counts should not be treated as a head-to-head causal contrast.

The record also lists selected serious-event terms with percentages. It does not specify the denominator for each percentage, whether events were judged treatment-related, or whether the list is exhaustive. No comparative risk estimate or uncertainty interval for these terms is reported.

What statistical details are absent?

The endpoint method and censoring description are available, but a full statistical analysis plan is not reported in the registry record. Details of covariate adjustment, stratification, planned subgroup analyses, interim analyses, multiplicity handling, confidence intervals, and hypothesis tests are not reported. The record lists 11 outcome measures and 9 analyses, but those counts do not establish how outcomes were prioritized or how multiple testing was addressed.

For general interpretation, confidence intervals describe the range of estimates compatible with the data and model at a stated confidence level. They help show precision; they do not remove bias from a non-comparable design. No confidence intervals for the primary endpoint are reported in the registry record. The record also does not report an observed treatment-effect estimate that could be used to judge statistical precision or clinical relevance.

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 Induction, Rituximab Maintenance", "Rituximab Induction, Observation Maintenance")
n      <- c(101, 101)
events <- c(30, 35)
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 Induction, Rituximab Maintenance  101  30  29.7  21.0  39.6  21.7  39.2  21.7  39.3
ARM  Rituximab Induction, Observation Maintenance  101  35  34.7  25.5  44.8  26.1  44.3  26.1  44.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures and 9 analyses. The primary endpoint is progression-free survival from randomization, with assessments specified at 12, 24, and 34 months. Secondary outcomes include progression, disease-free survival, overall survival, response during induction, molecular response, and duration of response. The record does not report how the primary and secondary outcomes were prioritized for statistical testing, or how the number of outcomes and time points was addressed.

In general, testing multiple outcomes or time points can increase the chance of observing a nominally unusual result even when there is no underlying effect. Statistical approaches can control that risk or distinguish confirmatory from exploratory analyses. Which approach, if any, was planned or used is not reported in the registry record. No interim analyses or stopping rules are reported either.

The primary endpoint description identifies the ITT population, but the record does not report the number analyzed for that endpoint or how missing outcome information was handled. It states that responding participants and participants lost to follow-up were censored at their last assessment date. Further details about missing data, reasons for loss to follow-up, follow-up completeness, and sensitivity analyses are not reported. Censoring preserves observed follow-up information, but does not establish later event status.

Because the registry lists allocation as NA and the model as single group, the meaning of the ITT label and the membership of the follow-up groups remain unclear. The record does not report a protocol-level analysis population definition or enough detail to determine whether participants were analyzed according to an original randomized assignment. These omissions limit assessment of multiplicity, missingness, and analysis-population choices.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cholelithiasis (3.0%), hepatitis b (2.0%), myocardial infarction (2.0%), pneumonia (2.0%), angina pectoris (2.0%).

The registry reports serious-event and other-event counts separately for induction and follow-up. For the induction phase, 233 participants are listed at risk, with 19 affected by serious events and 230 affected by other events. For rituximab maintenance follow-up, 101 are listed at risk, with 19 affected by serious events and 73 by other events. For observation maintenance follow-up, 101 are listed at risk, with 17 affected by serious events and 55 by other events.

These figures describe the registry's group counts; they should not be read as direct comparative treatment effects. The induction and follow-up periods differ, and the record does not establish the two follow-up groups as randomized, like-for-like controls. It also does not report exposure duration, event-level counting rules, or a detailed definition of the “other” category. The counts do not indicate whether events were considered related to treatment.

The registry lists cholelithiasis at 3.0%, hepatitis B at 2.0%, myocardial infarction at 2.0%, pneumonia at 2.0%, angina pectoris at 2.0%, and pyrexia at 1.0% among the top serious-event terms. Denominators and comparative analyses for these percentages are not reported in the registry record. These entries identify reported terms and frequencies; they do not, by themselves, establish causation or differences in risk between groups.

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

The record establishes how the primary endpoint was defined and how the progression-free survival function was estimated. It specifies progression, relapse, or death from any cause as events and states that Kaplan-Meier estimation was used, with censoring at the last assessment for responders and participants lost to follow-up. It also identifies the ITT population and the scheduled time points of 12, 24, and 34 months.

It does not report the primary endpoint estimates, event totals, confidence intervals, or p-values. Therefore, the amount of progression-free survival observed at the specified times, and the precision of those estimates, cannot be stated from the registry entries. The absence of those values is not evidence that the outcome was favorable or unfavorable.

The record also does not establish a randomized comparison, despite the wording of the study title. Its design fields describe a single-group model and allocation as NA, and the registry warns that the arms are not a like-for-like control comparison. The follow-up group counts cannot therefore be interpreted as an unbiased estimate of the effect of rituximab maintenance versus observation. The process that determined group membership is not reported in the registry record.

The safety entries are descriptive counts and selected serious-event percentages. They do not provide a full comparative safety analysis, and the listed terms do not establish that treatment caused an event. The record does not give enough detail about denominators, exposure, event definitions, or treatment attribution to support stronger interpretation.

In general, statistical results are most informative when an outcome estimate is presented with its uncertainty and when the design supports the comparison being made. Those pieces are not available for the primary endpoint in the registry entries. The record supports a description of the study question, endpoint definition, and selected safety information, but not a conclusion about the size or direction of a treatment effect.

14. Why This Trial Matters Statistically

This study illustrates why a trial's title and its registry design fields need to be read together. The official title describes a randomized maintenance comparison, while the registry identifies allocation as NA, describes a single-group model, and cautions that the arms are not like-for-like controls. The contrast is important because a treatment comparison depends not only on the outcomes measured, but also on how participants entered each group.

It also illustrates the distinction between defining an endpoint and reporting its result. The record gives a clear progression-free survival definition, identifies the Kaplan-Meier method, and specifies censoring at the last assessment for certain participants. Yet the estimates for the primary time points and their uncertainty are not reported in the registry record. Without those values, readers cannot assess the observed outcome magnitude or its precision.

The record further shows why safety counts need context. Counts appear for different phases and follow-up groups, but the group structure, exposure duration, and event-counting details are not reported. Selected serious-event terms are listed with percentages, but the relevant denominators and comparative analyses are absent. Descriptive counts remain useful for understanding what the registry reports, but they do not automatically establish a treatment-related difference.

Finally, numerous outcomes and analyses are listed, while the approach to multiplicity, missing data, and interim analyses is not reported in the registry record. These details matter for evaluating how robust an apparent result would be. The statistical lesson is to separate the prespecified clinical question, the available design evidence, and the actual numerical findings. In this case, the question and endpoint are described more fully than the primary outcome results or the basis for comparing follow-up groups.

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 registry record does not report numerical results for the primary progression-free survival endpoint, including estimates at 12, 24, and 34 months, event counts, confidence intervals, or p-values. This prevents assessment of the observed outcome and its precision. The endpoint description identifies an ITT population, but the number included in the analysis and the operational definition of that population are not reported.

There is uncertainty about the study structure. The official title describes randomization, whereas the registry lists allocation as NA and a single-group model, and explicitly warns that the groups are not like-for-like controls. The assignment process and the reasons for the maintenance and observation follow-up groups are not reported. This makes a comparative interpretation particularly limited.

The registry states that responders and participants lost to follow-up were censored at their last assessment, but does not report follow-up completeness, reasons for loss, sensitivity analyses, or checks of censoring assumptions. Further details of outcome assessment, including assessor masking, are not reported. The study is listed as open-label with no masking.

For safety, the record gives counts for serious and other events, and selected serious-event terms with percentages. It does not report exposure duration, detailed event definitions, whether events could be counted more than once, treatment attribution, or denominators for the term-specific percentages. These limits prevent a complete comparative safety interpretation.

Finally, the statistical analysis plan, sample-size justification, multiplicity approach, interim analyses, and handling of missing data beyond the stated censoring rule are not reported in the registry record. The listed target sample-size range is not a justification for the design or evidence of achieved statistical precision.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of MabThera (Rituximab) in Elderly Patients With Untreated Follicular Non-Hodgkin's Lymphoma (NHL) — NCT01144364.
• Registry record last updated 2017-08-15; status last verified 2017-06.
• Results first posted 2014-12-04.
• 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 a Phase 3, open-label study of rituximab induction followed by maintenance therapy or no further therapy in elderly patients with untreated advanced follicular lymphoma. It lists 234 participants enrolled, allocation as NA, and a single-group model. The record cautions that the follow-up groups are not a like-for-like control comparison, despite the randomized-comparison wording in the study title.

The primary endpoint is the percentage of participants with progression or death, measured as progression-free survival from randomization at 12, 24, and 34 months. The record specifies Kaplan-Meier estimation and censoring at last assessment for responding participants and those lost to follow-up. Numerical primary outcome results are not reported in the registry record.

Adverse-event counts are reported for induction and follow-up groups, along with selected serious-event terms and percentages. The information available does not establish comparative treatment effects or event causation. Details about the analysis plan, multiplicity, missing data, and the group assignment process are not reported.