A Study of Tocilizumab With or Without Methotrexate in Patients With Rheumatoid Arthritis.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Tocilizumab With or Without Methotrexate in Patients With Rheumatoid Arthritis. (NCT01010503), a na phase 4 study. The primary outcome is Percentage of Participants Adherent to Original Treatment.

2. Clinical Question

The study also listed disease activity and patient- and physician-reported measures as secondary outcomes. Those measures can describe different aspects of rheumatoid arthritis, but their presence does not create a control group or establish a treatment effect. The main focus described in the registry is adherence and persistence in the local clinical environment, rather than a randomized estimate of comparative efficacy.

3. Trial Design

This is a Phase 4, open-label, single-group, non-randomized study sponsored by Hoffmann-La Roche. The registry lists the study as completed, with a start date of 2009-06 and primary completion in 2010-05. Enrollment was 32. The record describes a target sample size of 20-50 patients and an anticipated treatment duration of 6 months.

Participants received tocilizumab 8 mg/kg as an intravenous infusion once every 4 weeks. The treatment could be given with methotrexate or, for participants intolerant to methotrexate, as monotherapy. Since the design has a single group and no random allocation, differences between treatment options are not estimated by the listed study design. Nor is there a contemporaneous control group against which changes in adherence, persistence, or disease activity can be compared.

Masking is listed as none, so the study was open-label. In general, open-label treatment means participants and study personnel know the treatment being given. That can be relevant when outcomes involve treatment continuation, decisions about changing doses, or assessments reported by participants or clinicians. The registry record does not describe methods intended to reduce any such influence.

The primary outcome is the percentage of participants adherent to original treatment at Week 24. The registry defines the relevant population as enrolled participants who received at least one dose, while its endpoint description specifies how treatment continuation and changes are handled. The outcome result itself is not reported. The record lists secondary measures including DAS28, global assessments of pain and disease activity, joint counts, ESR, and CRP. It does not report an analysis for these outcomes.

The registry does not report a statistical analysis plan, a justification for the target sample size, or details of any interim analyses. Those aspects of the trial should therefore not be inferred from its Phase 4 label, its enrollment, or the stated target range.

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: Intent-to-treat population (ITT), all enrolled participants who received at least one dose of study drug

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: All participants who received at least one dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants Adherent to Original Treatment, measured over Week 24.

The primary endpoint is titled “Percentage of Participants Adherent to Original Treatment” and has a timeframe of Week 24. It is intended to describe the proportion of the defined study population meeting the registry's operational definition of adherence to the original treatment pathway. Adherence and persistence are relevant in a study focused on whether participants remain on prescribed therapy over the study period, rather than only on a clinical measurement at a visit.

The endpoint description says that the adherence rate includes participants who received study drug beginning from Week 8 and remained until the end of the study. It also says the number represents participants with no changes in treatment protocol, participants with treatment discontinuation, and participants with dose reduction, but not participants who withdrew from the study prematurely. Because the definition includes treatment changes, discontinuation, and dose reduction, its label alone does not convey precisely how each treatment trajectory contributes to the numerator. The registry record does not provide further operational detail that resolves this wording.

The stated population is the intent-to-treat population, described as all enrolled participants who received at least one dose of study drug. That is the registry's stated analysis population; it should not be reinterpreted as a conventional randomized-population definition because the design is non-randomized. The primary percentage and its uncertainty are not reported in the registry record. Without the result and more detail on endpoint classification, readers cannot determine the observed adherence rate or how precisely it was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the study as open-label, non-randomized, and single-group. It does not report a statistical analysis plan. This distinction matters: the design labels tell readers how participants were assigned and whether treatment was masked, but do not specify the statistical methods used to analyze outcomes. Methods such as adjustment for baseline characteristics, handling of missing values, or construction of confidence intervals are not reported in the registry record.

What does a single-group design allow?

In general, a single-group study can describe outcomes observed among the participants who entered and received treatment. It does not directly estimate a contrast against a separate group. Without random allocation to a comparator, observed changes cannot be attributed to treatment by comparison with the course that would have occurred under a different treatment. Participants' characteristics, clinical care, and events over time may also contribute to what is observed. This is why descriptive evidence from a single group has a different interpretation from a randomized treatment comparison.

Here the registry lists no comparator and no randomization. It describes tocilizumab treatment, with methotrexate when used and monotherapy in cases of methotrexate intolerance. The record does not report a statistical comparison between those treatment pathways. It would therefore be inappropriate to interpret the study as a randomized comparison of combination treatment and monotherapy.

What does an estimate and its confidence interval convey?

In general, an estimate is a calculated summary of the observed data. A confidence interval conveys the statistical uncertainty around that estimate under the assumptions of the analysis: narrower intervals indicate greater precision, while wider intervals indicate less precision. An interval does not remove design limitations, such as the absence of a control group, nor does it guarantee that the analysis assumptions are appropriate.

The primary outcome is a percentage, but the registry record does not report its value or a confidence interval. It also does not identify a method for calculating uncertainty. No interval can therefore be interpreted for the primary endpoint from the posted record. The same limitation applies to the listed secondary outcomes, for which the record gives outcome names but no reported analyses.

How should the sample-size information be read?

The registry's study description states a target sample size of 20-50 patients, and the recorded enrollment is 32. A target range is not a statistical justification. The registry record does not report the assumptions behind the target, a planned power calculation, or a minimum clinically important difference. A reader should not infer these from enrollment alone.

The record also describes a separate planning illustration based on an observed effect. It states that the illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. For time-to-event outcomes, it describes total events; for other outcomes, it describes participants per arm. These are planning assumptions, not the design of this single-group trial and not a report of observed power. The record supplies no resulting sample-size figures to interpret, and the illustration does not substitute for the study's own design rationale.

Why can over-dispersion matter for event data?

In general, some statistical models for counts or proportions assume a particular relationship between the average outcome and its variability. Over-dispersion means that observed variability is greater than the model expects. If it is ignored, uncertainty can be understated and inferential results may appear more precise than warranted. The registry record does not identify a model for the primary endpoint or the adverse-event data, so there is no basis to say whether over-dispersion was assessed or whether it was relevant to the sponsor's analysis.

What is not documented?

The record lists zero analyses. It does not report a statistical plan, analysis methods, confidence intervals, or formal tests for the primary endpoint. It does not state whether any adjustment was made for baseline values or other covariates, or how multiple outcomes were handled. Nor does it describe interim analyses. These omissions do not prove that such methods were not used outside the registry record; they mean the methods are not reported in the registry record and cannot be evaluated from it.

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("Tocilizumab 8 mg/kg")
n      <- c(32)
events <- c(30)
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  Tocilizumab 8 mg/kg  32  30  93.8  79.2  99.2  79.9  98.3  79.8  98.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary adherence outcome and secondary measures including DAS28, patient global assessments of pain and disease activity, physician global assessment, swollen and tender joint counts, ESR, and CRP. It records 15 outcome measures, but zero analyses. The record does not state which outcomes were formally tested, whether any were exploratory, or whether a hierarchy was prespecified.

In general, when researchers test multiple outcomes, the chance of at least one apparently notable result can increase. Methods for addressing this issue may include designating a primary outcome, specifying a testing order, or adjusting inference. The registry record does not report a multiplicity strategy, so it is not possible to assess whether or how multiple-outcome inference was controlled. The presence of many listed outcomes alone does not establish that they were all analyzed or tested.

Missing-data handling is also not reported. The primary outcome description excludes participants who withdrew prematurely, but the record does not explain how such withdrawals were counted in the denominator, whether missing Week 24 assessments were imputed, or how other incomplete outcome data were handled. It also does not report the number of missing observations for the primary or secondary outcomes. These details matter because an endpoint based on treatment continuation may be affected by who remains under observation and how withdrawals are classified.

The stated primary population is all enrolled participants who received at least one dose of study drug. The registry calls this the intent-to-treat population, but it does not provide further analysis-population definitions or explain how deviations from treatment were handled. Since allocation was not randomized, this label should be read as the registry's description of the population, not as evidence of a randomized analysis set. The analysis population and missing-data methods are not reported in sufficient detail to evaluate possible bias.

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: crash of left foot local infection of skin and subcutaneous tissue (3.1%), bronchopneumonia (3.1%), lumbago (3.1%), congestive heart failure (3.1%).

The registry lists a tocilizumab 8 mg/kg group with 32 participants at risk for serious adverse events and 32 at risk for other adverse events. It records 3 participants with serious adverse events and 10 with other adverse events. These are descriptive counts for the study group, not comparisons between treatments. The record does not report a comparative estimate or an analysis of whether the groups differ, since there is no separate comparator group.

Four serious adverse-event terms are listed: crash of left foot local infection of skin and subcutaneous tissue, bronchopneumonia, lumbago, and congestive heart failure. Each term has a reported value of 3.1%. The registry does not explain whether terms overlap within participants, so the terms should not be added together to infer a total number of affected participants or events. The record also does not provide detail about timing, duration, severity beyond the serious-event classification, or relationship to study treatment.

The number of deaths is not reported in the registry record. The adverse-event figures do not establish that an event was caused by tocilizumab, nor do they permit a comparison with another therapy or background risk. They describe what the registry recorded in this study group.

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

The study addresses a practical question: how participants with moderate to severe active rheumatoid arthritis remained on a tocilizumab treatment pathway over the study period. The registry specifies a Week 24 adherence endpoint, describes an infusion schedule, and allows methotrexate combination treatment or monotherapy for methotrexate intolerance. This makes the study's focus on treatment persistence clear, even though the primary result is unavailable.

What the record does not show is the percentage meeting the endpoint definition. It also does not report the clinical outcome analyses named as secondary measures. Thus, readers cannot use the posted information to quantify adherence, disease activity change, or patient-reported change. No conclusion about the size or precision of those outcomes can be drawn from the outcome labels alone.

The absence of a comparator sets another boundary. This single-group, non-randomized design cannot provide a direct estimate of how outcomes would differ under another treatment. Even a fully reported within-group result would describe the observed experience of participants in this study, not establish a causal treatment advantage. Open-label conduct also matters when outcomes involve treatment decisions or subjective assessments, although the record does not document the influence of that feature.

The adverse-event counts and listed terms provide descriptive safety information, but without a comparator, detailed event timing, or attribution analysis, they do not establish comparative risk or causation. They should not be treated as a complete account of safety beyond the events recorded in the registry.

In short, the registry record documents a completed Phase 4 study, its design, treatment approach, planned adherence focus, and selected adverse-event information. It does not report the primary adherence estimate, secondary analyses, uncertainty measures, or detailed statistical methods. The evidence that can be interpreted is therefore limited to the design and descriptive information actually recorded.

14. Why This Trial Matters Statistically

Adherence studies address an aspect of treatment that clinical outcome trials may not capture fully: whether participants continue along the intended treatment pathway. A treatment schedule and an outcome measured at a study visit do not by themselves describe persistence, dose reduction, discontinuation, or protocol changes. The registry's focus on adherence and persistence makes those treatment experiences central to the research question.

This study is also a useful example of why endpoint definitions need to be read closely. The primary outcome is named adherence to original treatment, while its description includes participants with discontinuation and dose reduction as well as those without treatment changes. It separately excludes participants who withdrew prematurely. Without the outcome numerator and a clearer account of classification, the endpoint label cannot be translated confidently into a simple account of treatment continuation.

The single-group, non-randomized design illustrates the difference between describing a cohort and estimating a comparative effect. Such a study can provide information about experience in its setting, but it cannot answer how outcomes compare with a different treatment on the basis of randomization. The distinction is particularly important when the record also lists clinical outcomes: outcome names are not equivalent to analyses, and within-group observations are not a controlled treatment contrast.

Finally, the registry record demonstrates the importance of accessible results and methods. Without the primary percentage, an uncertainty estimate, analysis details, or missing-data procedures, readers cannot assess the precision or robustness of the intended adherence finding. The study remains relevant as a record of a real-world treatment question and a particular design, while its reported information places firm limits on statistical interpretation.

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 primary limitation for interpretation is that the registry record does not report the result for the primary endpoint. It gives the outcome title, timeframe, population description, and operational definition, but not the percentage, numerator, denominator used in the calculation, or an uncertainty estimate. The main study question therefore cannot be answered quantitatively from the record.

The endpoint wording is not fully transparent. It describes an adherence rate while including participants with treatment discontinuation and dose reduction, and it excludes those who withdrew prematurely. The record does not explain how these categories were classified or how they relate to adherence to original treatment. This makes the outcome difficult to interpret even apart from the missing numerical result.

The study has no randomized comparator and is described as single-group and non-randomized. Consequently, the design cannot isolate treatment effects from other influences or support a direct comparison with another treatment. The open-label design may also affect treatment decisions and subjective assessments; the registry does not describe safeguards or analytic adjustments related to that feature.

Although multiple secondary outcomes are listed, analyses are not reported. Statistical methods, multiplicity handling, missing-data procedures, baseline summaries, and any interim analyses are not reported in the registry record. The number of deaths is also not reported. The serious-event terms and counts are descriptive, with no comparative estimate or treatment-attribution detail.

Finally, the stated target sample-size range is not accompanied by a design justification in the registry record. Enrollment alone does not establish whether the study was adequately sized for its primary question. The sample-size planning illustration described in the record is not the study's own design and should not be mistaken for a study-specific power calculation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Tocilizumab With or Without Methotrexate in Patients With Rheumatoid Arthritis. — NCT01010503.
• Registry record last updated 2014-08-13; status last verified 2014-07.
• Results first posted 2014-08-13.
• 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

NCT01010503 is a completed Phase 4, open-label, non-randomized, single-group study of tocilizumab in moderate to severe active rheumatoid arthritis. The registry records enrollment of 32 participants and describes treatment with tocilizumab 8 mg/kg by intravenous infusion once every 4 weeks, with methotrexate or monotherapy in cases of methotrexate intolerance.

The primary outcome was the percentage adherent to original treatment at Week 24. Its result and statistical analysis are not reported in the registry record. The record lists secondary disease activity and patient- and physician-assessment outcomes but no analyses. It records 3 participants with serious adverse events and 10 with other adverse events; four serious-event terms are listed at 3.1% each. The number of deaths is not reported.

The design supports descriptive interpretation of the study group, not a randomized comparison. The registry does not report a statistical plan, missing-data methods, or a sample-size justification.