Safety and Efficacy of ACZ885 in Adult Patients With Established Rheumatoid Arthritis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of ACZ885 in Adult Patients With Established Rheumatoid Arthritis (NCT00504595), a randomized phase 2 study. The primary outcome is Response to Treatment (ACR20) in Adult Patients With Established Rheumatoid Arthritis (RA).

2. Clinical Question

3. Trial Design

The registry describes a Phase II, randomized, multicenter, double-blind, placebo-controlled, parallel-group study. Its official title identifies a 12-week study. Masking is recorded as quadruple, and the enrollment is 80. The record lists rheumatoid arthritis as a condition and identifies Novartis as sponsor. The study status is completed, with a start recorded as 2007-05 and primary completion recorded as 2008-09.

ACZ885, also called canakinumab in the arm descriptions, was compared with placebo. In rheumatoid arthritis patients, each arm is described as receiving intravenous study medication on Day 1, Day 15, and Day 43. The record separately describes healthy volunteers receiving a single administration on Day 1. It does not explain how the healthy-volunteer cohort related to the rheumatoid arthritis treatment comparison, so the cohorts should not be treated as interchangeable.

The primary outcome was ACR20 response in adults with established rheumatoid arthritis, assessed at 6 weeks and 12 weeks. Secondary outcomes concerned response measured with the Simple Disease Index and the Disease Activity Score (DAS28). The record lists 3 outcome measures, but the secondary outcome names alone do not provide their results or analysis details.

Randomization and masking can help limit systematic differences in treatment assignment and outcome assessment. They do not, by themselves, establish that the groups were comparable in every respect or show the size or precision of a treatment effect. The allocation ratio, randomization procedure, concealment details, and full statistical analysis plan are not reported in the registry record. Primary outcome counts and a sponsor-reported analysis are also not reported, so the registry’s design information cannot substitute for a results comparison.

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: The Safety Analysis Set consisted of all subjects who received at least one dose of study medication. The analysis used last observation carried forward (LOCF) imputation for missing values.

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 Response to Treatment (ACR20) in Adult Patients With Established Rheumatoid Arthritis (RA), measured over 6 weeks and 12 weeks.

The primary endpoint is the number of participants who met the ACR20 response definition at 6 weeks and 12 weeks. The registry defines a responder as having at least 20% improvement in both tender and swollen 28-joint counts, together with 20% improvement in at least 3 of 5 other measures. Those measures are the patient’s pain assessment, patient’s global assessment of disease activity, physician’s global assessment of disease activity, patient self-assessed disability measured with the Health Assessment Questionnaire, and the acute phase reactant high sensitivity C-reactive protein.

ACR20 turns several clinical measurements into a binary classification: a participant either meets the response definition at an assessment or does not. That makes the endpoint interpretable as a response count or proportion, while combining joint counts with patient, clinician, function, and laboratory measures. It does not describe the full amount of change in each component, and the threshold does not distinguish a response just meeting the criterion from a larger response.

The registry gives two assessment times, 6 weeks and 12 weeks, rather than a single endpoint time. This matters because response status can differ across visits, and each time point requires its own interpretation. Primary outcome counts and comparisons for these visits are not reported in the registry record. The endpoint definition therefore explains what was intended to be measured, but does not establish the observed response in either arm.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, double-blind, placebo-controlled, parallel-group Phase II study. Randomization is intended, in general, to reduce systematic differences between treatment groups at assignment. Blinding is intended, in general, to reduce the influence of treatment knowledge on care, reporting, and assessment. These design features can strengthen a comparison, but their presence alone does not show that bias was eliminated. Details of the randomization procedure, concealment, and masking implementation are not reported in the registry record.

What does the primary endpoint count?

The primary outcome is a binary response: whether each participant met the ACR20 criterion at an assessment. The registry specifies improvement thresholds for joint counts and additional measures. In general, a binary endpoint simplifies a complex clinical response into a classification that can be counted by treatment group. This is easy to communicate, but it discards information about the size of change within each component and about changes that do not cross the response threshold.

The outcome is assessed at 6 weeks and 12 weeks. Results at separate visits should be understood as separate assessments, not as interchangeable estimates. A result at one visit would not automatically describe the other visit. The registry does not report the arm-level outcome counts or the statistical comparison at either assessment, so no response proportion, treatment contrast, confidence interval, or p-value can be stated.

How should uncertainty be understood?

In general, an estimate describes the effect observed in a study, while a confidence interval describes the range of values reasonably compatible with the data under the model used. A narrow interval indicates more precision than a wide interval; neither guarantees that the model or study design is free of bias. A p-value, when reported, addresses compatibility between observed data and a specified null model, not the probability that a treatment is effective. The registry record does not report a confidence interval, p-value, or sponsor analysis for the primary outcome. Because the outcome data are absent, uncertainty around the intended treatment comparison cannot be assessed from this record.

What do the posted safety counts represent?

The safety entries give numbers at risk and numbers affected for serious and other adverse events, with separate entries for healthy volunteers and rheumatoid arthritis patients. These entries are descriptive. General comparisons of adverse-event counts require attention to the population, exposure, event definition, observation period, and completeness of reporting. The record does not supply sufficient detail to establish whether those considerations were handled comparably across groups. Counts should not be converted into a causal treatment effect or used to claim a difference without the relevant analysis and context.

The registry also lists selected serious adverse event terms with percentages. A term-level percentage is not the same as a complete account of all events, and the record does not explain the basis for each term’s percentage or link the terms to a specific treatment group. The group-specific fields and term list therefore answer different descriptive questions and should not be combined into a new estimate.

What do the planning illustrations mean?

The stated sample-size assumptions describe a planning illustration based on the observed effect, not the trial’s own design. The assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and a target effect defined as a stated fraction of the observed effect. In general, such an illustration estimates the participants per arm that might be needed under those assumptions. It is not the study’s observed power, a retrospective test of whether the trial succeeded, or proof that the original design was adequate.

Since the primary outcome result is not reported, no observed effect can be interpreted from the registry information. The planning assumptions alone do not supply an effect estimate, a variance, or a clinical conclusion. The sample-size justification and the trial’s original statistical planning are not reported in the registry record. The assumptions should therefore be read only as hypothetical inputs for a planning calculation, not as a description of the sponsor’s protocol.

More broadly, a statistical analysis depends on the outcome definition, population, missing-data handling, model, and planned comparison. Some of these details are present in the registry, including the ACR20 definition, the named analysis set, and LOCF. Other details—including the testing procedure and adjustment for multiple comparisons—are not reported in the registry record. Without those details and the primary results, the statistical evidence for the main question cannot be reconstructed.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is assessed at 6 weeks and 12 weeks, and the registry also names secondary outcomes using SDAI and DAS28. Considering several outcomes or assessment times can create multiplicity: in general, the chance of at least one apparently notable finding can increase when many statistical tests are performed. Planned test hierarchy, multiplicity adjustment, and the statistical criteria for interpreting the outcomes are not reported in the registry record. The record therefore does not establish how the investigators intended to handle multiple comparisons.

The registry says the primary outcome analysis used last observation carried forward (LOCF) for missing values. In general, LOCF carries a participant’s most recently observed value forward to a later assessment. This can preserve an analysis record for participants with a missing visit, but it relies on assumptions about what the unobserved later value would have been. If participant status changes after the last recorded assessment, carrying the earlier value forward may not represent that change. The record does not report the amount or pattern of missing data, reasons for missingness, or sensitivity analyses that might test the influence of this method.

The primary outcome population is described as the Safety Analysis Set, defined as subjects who received at least one dose of study medication. The registry does not report whether an intention-to-treat population, per-protocol population, or other analysis set was used for efficacy comparisons. It also does not report participant flow or the handling of withdrawals beyond the LOCF statement. These omissions limit assessment of how the analyzed population relates to the randomized groups.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: deafness neurosensory (2.0%), ear infection (2.0%), sinusitis (2.0%), musculoskeletal chest pain (2.0%).

The registry separates safety entries for healthy volunteers and rheumatoid arthritis patients, and distinguishes serious from other adverse events. For serious adverse events, the entries are 0 affected among 10 at risk for ACZ885 healthy volunteers, 0 among 10 for placebo healthy volunteers, 2 among 50 for ACZ885 rheumatoid arthritis patients, and 0 among 10 for placebo rheumatoid arthritis patients. For other adverse events, the corresponding entries are 6 among 10, 4 among 10, 12 among 50, and 8 among 10. These are counts recorded in the registry, not adjusted comparisons.

The group sizes and populations differ, so the counts should be read within their stated groups rather than compared as if the cohorts were identical. The registry does not report exposure-adjusted rates, a formal safety comparison, or a detailed event-collection method. It lists Deafness Neurosensory, Ear Infection, Sinusitis, and Musculoskeletal Chest Pain as serious adverse event terms, each recorded as 2.0%, without enough context to assign those terms to a particular group. Death counts are not reported in the registry record. Absence of a posted count is not evidence that no event occurred.

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

The record establishes what investigators planned to study: a randomized, placebo-controlled Phase II comparison involving ACZ885 in adults with established rheumatoid arthritis, with ACR20 response assessed at 6 weeks and 12 weeks. It also provides the response definition, the recorded treatment schedules, and selected safety entries. Those details make the intended clinical question understandable, but they do not answer it.

Most importantly, the registry does not report the primary ACR20 counts or a treatment comparison. It is therefore not possible to state whether more participants met the response definition in either group, how large any difference was, or how precisely a difference was estimated. The record also does not provide the sponsor’s primary analysis. No efficacy conclusion should be inferred from the trial title, study status, design, endpoint definition, or planning assumptions.

The posted adverse-event counts can be described, but should not be treated as proof of a safety difference. Counts alone do not account for the full context needed for comparison, and the healthy-volunteer and rheumatoid arthritis cohorts are distinct populations. The selected serious-event terms do not replace complete group-level safety reporting. Death counts are not reported in the registry record.

In general, a trial can inform a clinical question only to the extent that its results, methods, and uncertainty are available and interpretable. A randomized and masked design is relevant to credibility, but it cannot fill in missing outcome results. Likewise, an endpoint definition identifies what would count as a response but does not show that a response occurred. The record supports a careful description of design and reporting gaps, not a conclusion about treatment benefit or harm.

13. Why This Trial Matters Statistically

This trial is statistically interesting because its primary outcome combines several types of information into a responder classification. ACR20 requires improvement in both joint-count measures and improvement across a specified subset of other measures. That structure creates a clinically interpretable threshold, while making the result dependent on several component assessments. A participant near the threshold may be classified differently from someone with a similar pattern of change who falls just short of one criterion.

The repeated assessment at 6 weeks and 12 weeks also makes the analysis question more than a single cross-sectional comparison. The registry record identifies both times but does not report results for either or explain how inference across them was planned. The named secondary outcomes add further scope for multiple comparisons, while the record does not report a multiplicity strategy.

The missing primary outcome results illustrate a basic distinction in trial interpretation: a sound design and a clearly defined endpoint do not by themselves provide evidence about the estimated effect. Without arm-level data and uncertainty estimates, readers cannot judge the size, precision, or direction of the intended comparison. This is not remedied by the registry’s sample-size assumptions, which describe a planning illustration rather than observed power.

The safety entries also show why population and outcome context matter. Healthy volunteers and rheumatoid arthritis patients appear in separate groups, and serious and other adverse events are recorded separately. The group-level counts are useful descriptive information, but the registry record does not give the analysis details required for a formal comparative safety assessment. Taken together, the record illustrates why transparent outcome reporting, missing-data methods, analysis populations, and multiplicity plans are important for interpreting a clinical trial.

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 principal limitation is that the registry record does not report the primary ACR20 outcome counts or an analysis comparing ACZ885 with placebo. The endpoint has assessments at 6 weeks and 12 weeks, and the record does not provide results at either time. Consequently, effect size and statistical precision cannot be evaluated from the posted results.

The registry identifies LOCF for missing primary outcome values but does not report how much data were missing, when observations were missing, why they were missing, or whether sensitivity analyses were conducted. The stated analysis population is the Safety Analysis Set, but the record does not provide enough information to determine how this relates to all randomized participants or whether additional analysis sets were used.

Several details that support interpretation are not reported in the registry record: the allocation ratio and randomization procedures, the detailed statistical analysis plan, the approach to multiplicity, and the basis for the sample-size design. The record’s planning assumptions are not evidence of the trial’s original design or observed power.

The safety information is also limited. Counts are posted for healthy volunteers and rheumatoid arthritis patients, but detailed exposure, event ascertainment, and comparative safety analyses are not reported. Selected serious-event terms are listed with percentages but are not linked to a particular group in the record. Death counts are not reported in the registry record. These limitations prevent a complete assessment of efficacy or safety from the available registry information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of ACZ885 in Adult Patients With Established Rheumatoid Arthritis — NCT00504595.
• Registry record last updated 2012-08-07; status last verified 2012-08.
• Results first posted 2011-06-23.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes a completed, randomized, double-blind, placebo-controlled, parallel-group Phase II study of ACZ885 in established rheumatoid arthritis, with healthy volunteers also included in the arm descriptions. The rheumatoid arthritis regimen is recorded as intravenous study medication on Day 1, Day 15, and Day 43. The primary endpoint is ACR20 response at 6 weeks and 12 weeks, with secondary outcomes named using SDAI and DAS28.

The registry defines ACR20 and describes LOCF handling and the Safety Analysis Set. It posts group-level serious and other adverse-event counts, along with selected serious-event terms. However, primary ACR20 counts, an efficacy comparison, the sponsor’s analysis, and death counts are not reported in the registry record. The posted information therefore describes the intended study and selected safety data, but does not support an efficacy conclusion or a complete comparative safety assessment.