Evaluation of the Efficacy and Safety of Two Dosing Regimens of Olokizumab (OKZ), Compared to Placebo and Adalimumab, in Subjects With Rheumatoid Arthritis (RA) Who Are Taking Methotrexate But Have Active Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Efficacy and Safety of Two Dosing Regimens of Olokizumab (OKZ), Compared to Placebo and Adalimumab, in Subjects With Rheumatoid Arthritis (RA) Who Are Taking Methotrexate But Have Active Disease (NCT02760407), a randomized phase 3 study. The primary outcome is Percentage of Subjects Achieving American College of Rheumatology 20% (ACR20) Response.

2. Clinical Question

3. Trial Design

This was a randomized, double-blind, parallel-group, placebo- and active-controlled, multicenter Phase III study. The registry reports enrollment of 1648 and status as completed. It lists four groups: olokizumab 64 mg every 4 weeks plus methotrexate, olokizumab 64 mg every 2 weeks plus methotrexate, adalimumab 40 mg every 2 weeks plus methotrexate, and placebo every 2 weeks plus methotrexate. The registry record does not report the number of study centers.

The treatment regimens were designed to preserve blinding. The q4w olokizumab group received placebo injections at alternate times, while the other groups had injections according to their assigned regimens. Methotrexate was background therapy in all four groups, described as being maintained at a stable dose and route of administration. The registry does not report additional details about treatment changes or rescue therapy in the material describing these results.

There were 479 participants in the q4w olokizumab group, 464 in the q2w olokizumab group, 462 in the adalimumab group, and 243 in the placebo group for the primary endpoint counts. The primary outcome was assessed at Week 12. Its definition combines achieving the clinical response criteria with remaining on randomized treatment and in the study at that assessment. All randomized participants were included in the stated primary analysis population, with analyses assigned according to randomized treatment group.

The design included several questions rather than only a placebo comparison: whether each olokizumab regimen differed from placebo, and how olokizumab compared with adalimumab. The registry reports sponsor superiority analyses for the two olokizumab-versus-placebo primary comparisons and additional analyses for selected secondary outcomes. Original design details such as the planned sample-size justification and the full statistical analysis plan are not reported in the registry record.

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 (ITT) population: The ITT population includes all randomized subjects. Subjects were analyzed according to the treatment group to which they were randomized. The ITT population is the primary analysis 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.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Subjects Achieving American College of Rheumatology 20% (ACR20) Response, measured over at Week 12.

The primary endpoint was the percentage of subjects achieving an American College of Rheumatology 20% response at Week 12. The registry defines a responder as a participant who satisfied the ACR20 criteria and remained on randomized treatment and in the study at Week 12. The response criteria require improvement from baseline in both swollen and tender joint counts, together with improvement in at least three of five additional core measures: patient global assessment of disease activity, patient assessment of pain, physical ability measured by HAQ-DI, physician global assessment, and the acute-phase reactant CRP. The joint counts use 66 joints for swelling and 68 joints for tenderness.

ACR20 is a composite endpoint: it combines joint findings with patient, physician, physical-function, and laboratory measures. This is intended to represent change across several aspects of rheumatoid arthritis rather than a change in only one measure. A binary response also makes the comparison directly interpretable as the proportion meeting the criteria in each group. The primary comparison was the difference between each olokizumab regimen and placebo in this response proportion.

Requiring participants to remain on randomized treatment and in the study is part of the endpoint definition, not just a description of the joint and other clinical criteria. Therefore, the reported response counts reflect both the response criteria and that continued-treatment-and-study condition. The registry identifies the intent-to-treat population as the primary analysis population, including all randomized subjects analyzed according to their randomized group. Details about how particular missing Week 12 measurements were handled beyond the responder definition are not reported in the registry record.

7. Results Posted in the Registry

• Arm 1: Olokizumab q4w + Methotrexate: 71.4% (342/479) versus 44.4% (108/243) on control; risk difference 27.0 percentage points (95% CI 19.5 to 34.4), risk ratio 1.61 (1.38–1.87); unadjusted two-proportion z-test p = <0.001.
• Arm 2: Olokizumab q2w + Methotrexate: 70.3% (326/464) versus 44.4% (108/243) on control; risk difference 25.8 percentage points (95% CI 18.3 to 33.3), risk ratio 1.58 (1.36–1.84); unadjusted two-proportion z-test p = <0.001.
• Arm 3: Adalimumab q2w + Methotrexate: 66.9% (309/462) versus 44.4% (108/243) on control; risk difference 22.4 percentage points (95% CI 14.9 to 30.0), risk ratio 1.50 (1.29–1.76); unadjusted two-proportion z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Percentage of Subjects Achieving ACR20 Response: Olokizumab Comparison With Adalimumab

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Arm 1: Olokizumab q4w + Methotrexate: 71.4% (342/479) versus 44.4% (108/243) on control; risk difference 27.0 percentage points (95% CI 19.5 to 34.4), risk ratio 1.61 (1.38–1.87); unadjusted two-proportion z-test p = <0.001.
  • Arm 2: Olokizumab q2w + Methotrexate: 70.3% (326/464) versus 44.4% (108/243) on control; risk difference 25.8 percentage points (95% CI 18.3 to 33.3), risk ratio 1.58 (1.36–1.84); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 1: Olokizumab q4w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 2: Olokizumab q2w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Percentage of Subjects Achieving Low Disease Activity

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Arm 1: Olokizumab q4w + Methotrexate: 45.9% (220/479) versus 12.8% (31/243) on control; risk difference 33.2 percentage points (95% CI 27.0 to 39.3), risk ratio 3.60 (2.56–5.07); unadjusted two-proportion z-test p = <0.001.
  • Arm 2: Olokizumab q2w + Methotrexate: 45.3% (210/464) versus 12.8% (31/243) on control; risk difference 32.5 percentage points (95% CI 26.3 to 38.7), risk ratio 3.55 (2.52–5.00); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 1: Olokizumab q4w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 2: Olokizumab q2w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Percentage of Subjects Achieving Low Disease Activity: Olokizumab Comparison With Adalimumab

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Arm 1: Olokizumab q4w + Methotrexate: 45.9% (220/479) versus 12.8% (31/243) on control; risk difference 33.2 percentage points (95% CI 27.0 to 39.3), risk ratio 3.60 (2.56–5.07); unadjusted two-proportion z-test p = <0.001.
  • Arm 2: Olokizumab q2w + Methotrexate: 45.3% (210/464) versus 12.8% (31/243) on control; risk difference 32.5 percentage points (95% CI 26.3 to 38.7), risk ratio 3.55 (2.52–5.00); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 1: Olokizumab q4w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Arm 2: Olokizumab q2w + Methotrexate than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted secondary results extend the Week 12 response assessment to active-comparator questions and other disease-activity and function outcomes. The registry includes ACR20 comparisons involving adalimumab, low disease activity, HAQ-DI change, ACR50 response, and CDAI remission among its listed secondary outcome measures. Not all secondary outcomes have posted numerical results in the record, so the overall pattern cannot be assessed uniformly across every listed measure.

Among the secondary results with posted analyses, the sponsor reported positive superiority comparisons against placebo for adalimumab ACR20 and for both olokizumab regimens on low disease activity. The record also labels q4w olokizumab versus adalimumab on ACR20 as non-inferiority. These findings are directionally related to the primary result in that they concern response or disease activity at Week 12, but they assess different comparisons or outcome definitions. They should not be treated as repeated measurements of the same primary question.

The secondary results add context, but the primary endpoint was specifically defined as ACR20 response for each olokizumab regimen versus placebo. ACR20, low disease activity, physical function, ACR50, and CDAI remission represent distinct outcomes. Evidence on one cannot automatically establish a result on another. In particular, the registry record does not report numerical results for all six posted secondary outcomes, and it does not provide enough information to infer a complete pattern for the unreported results.

General explanation: secondary analyses often carry less inferential weight when many outcomes or comparisons are examined without a clearly reported multiplicity strategy. Repeated testing can raise the chance that some results appear statistically persuasive by chance alone. The registry reports 19 analyses across 7 outcome measures but does not report the full testing hierarchy or multiplicity adjustment. Therefore, the posted secondary p-values and confidence intervals are informative descriptions of their individual contrasts, but their evidential status should not be assumed to match that of a prespecified primary comparison.

The active-comparator result also has a distinct interpretation from placebo superiority. Non-inferiority requires a prespecified margin and testing rules, neither of which is reported in the registry record. The designation is part of the sponsor-reported analysis, but readers cannot independently reconstruct the criterion from the posted summary alone.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Percentage of Subjects Achieving ACR20 Response: Olokizumab Comparison With Adalimumab
• Percentage of Subjects Achieving Low Disease Activity
• Percentage of Subjects Achieving Low Disease Activity: Olokizumab Comparison With Adalimumab
• Improvement of Physical Ability From Baseline to Week 12, as Measured by the Health Assessment Questionnaire-Disability Index (HAQ-DI)
• Percentage of Subjects Achieving American College of Rheumatology 50% (ACR50) Response
• Percentage of Subjects With Clinical Disease Activity Index (CDAI) ≤ 2.8 (Remission)

9. Statistical Interpretation

10. Statistical Methods Explained

For a binary endpoint such as ACR20 response, each participant is classified as meeting or not meeting the response definition. The reported arm counts give the number meeting the definition and the number analyzed for that endpoint. A risk difference compares the two response proportions by subtracting one group’s proportion from the other. Positive values in the olokizumab-versus-placebo comparisons mean a higher observed response proportion in the olokizumab group. The sponsor reported risk differences of 0.270 and 0.258 for the two primary comparisons.

General explanation: a confidence interval describes statistical uncertainty around an estimated contrast. Its width is influenced by the amount of information in the data and by variability. A narrower interval indicates greater precision under the analysis model; a wider interval indicates less precision. An interval that does not include zero is consistent with a nonzero risk difference at the corresponding confidence level under the methods used. The interval alone does not resolve whether an effect is clinically important.

The sponsor’s reported primary analyses used chi-squared methods and were labeled superiority analyses. In a superiority framework, the question is whether the data support a difference in the specified direction or whether the groups differ, according to the prespecified testing approach. The registry gives p < 0.001 for both primary olokizumab-versus-placebo analyses. General explanation: a p-value is calculated under a null hypothesis and statistical model; it is not the probability that the null hypothesis is true, and it does not quantify the probability that a result will be repeated.

The registry also posts simple unadjusted re-calculations from the arm-level counts. These are useful as a transparent check of the broad contrast, but they are not a substitute for the sponsor’s own reported analysis. Re-calculation may use a different confidence-interval construction or testing approach from the sponsor analysis. The sponsor reports the primary risk differences to three decimal places and uses 97.5% confidence intervals, while the simple re-calculations use their own posted estimates and intervals. The registry does not describe enough detail to attribute every numerical difference to a particular methodological choice.

Confidence levels and p-values should be interpreted together with the analysis plan and multiplicity strategy. A confidence interval’s coverage level is the long-run property of the procedure under its assumptions; it is not a probability statement about the fixed effect after observing the data. The sponsor reports 97.5% intervals for the two primary comparisons, and the registry labels both as superiority. The full rationale for the confidence level, testing sequence, and multiplicity control is not reported in the registry record.

The primary analysis population is the intent-to-treat population, defined as all randomized subjects analyzed according to the group to which they were randomized. This preserves the randomized assignment in the analysis. General explanation: analyzing participants as randomized can help maintain the comparability created by randomization, even if some participants do not follow their assigned treatment perfectly. The endpoint itself additionally requires remaining on randomized treatment and in the study at Week 12, so the outcome definition incorporates that condition. Specific imputation rules for missing assessments, treatment discontinuations, or other intercurrent events are not reported in the registry record.

The posted study contains multiple outcomes and analyses. The registry lists 7 outcome measures, 19 analyses, and 6 posted secondary outcomes. General explanation: when many hypotheses are tested, the chance of at least one apparently positive finding can increase if each is judged independently at an ordinary significance threshold. Methods such as hierarchical testing or other multiplicity adjustments can address that issue, but the registry record does not report whether or how such procedures were used across the full set of analyses. The reported sponsor analysis types and confidence levels should therefore be distinguished from assumptions about unreported testing procedures.

The active-comparator secondary analyses include a reported non-inferiority classification for q4w olokizumab compared with adalimumab on ACR20 response. General explanation: a non-inferiority conclusion ordinarily depends on a prespecified margin that defines how much lower an effect could be while still meeting the study’s criterion. The registry reports a risk difference of 0.045 and a 97.5% confidence interval from -0.022 to 0.112 for that comparison, with the analysis labeled non-inferiority. The margin and further decision rules are not reported in the registry record, so the label alone does not permit independent evaluation of the non-inferiority criterion.

General explanation: over-dispersion is a concern when observed variation exceeds what a statistical model expects. It is especially relevant to count outcomes and some clustered data models. The primary endpoint is a binary participant-level response, and the posted sponsor method is chi-squared; the registry does not report an over-dispersion assessment. No additional statistical plan, interim-analysis details, or adjustment model is reported in the registry record.

11. Confidence Intervals and Precision

The sponsor’s primary risk-difference estimate for q4w olokizumab versus placebo was 0.270, with a 97.5% confidence interval from 0.183 to 0.352. For q2w olokizumab versus placebo, the reported estimate was 0.258, with a 97.5% confidence interval from 0.171 to 0.341. The interval endpoints are all above zero, and the sponsor labeled both analyses superiority. The p-values were each reported as p < 0.001.

General explanation: an interval communicates precision as well as direction. The range of values within each interval represents the uncertainty associated with the estimate under the statistical method and assumptions used. The q4w and q2w intervals overlap substantially; this does not by itself test whether the two dosing schedules are equal or different. A direct comparison between the two olokizumab schedules is not reported for the primary endpoint.

The intervals also reflect the particular analysis and confidence level. The sponsor used 97.5% confidence intervals for the primary comparisons. The simple unadjusted re-calculations posted from arm-level summary statistics produce somewhat different interval limits from the sponsor’s reported limits, while giving similar point estimates. Such differences can arise from methods that are not identical; specific causes are not reported. The sponsor’s own reported analysis is the formal registry result.

Precision is not the same as clinical importance or generalizability. A narrow interval can still surround an effect whose importance depends on clinical context, and an interval from a randomized study does not establish how results would apply beyond the enrolled population or the Week 12 assessment. The registry does not provide a threshold for a clinically important risk difference. The intervals quantify uncertainty about the specified contrasts, not uncertainty about every possible outcome or population.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations expressed as participants per arm for the binary outcomes in this study. They are not total event counts. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each scenario uses the stated fraction of the observed effect as the effect to detect. The trial’s own original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the illustrative participants per arm for a design intended to have an 80% chance of detecting the specified effect under the planning assumptions, if that effect and the model assumptions were correct. The 90% power column gives the corresponding per-arm planning figure for a 90% chance. These are design concepts, not guarantees: actual performance depends on the true effect, event proportions, analysis method, and other assumptions.

The rows use the observed effect, three-quarters of the observed effect, and half of the observed effect. The planning entries illustrate that a smaller effect requires more participants per arm to maintain the same target power. For example, the primary q4w-versus-placebo scenario lists 52 participants per arm for 80% power when planning for the full observed effect, compared with 215 when planning for half of that effect. These figures are hypothetical planning calculations, not the randomized group sizes reported for the trial.

The associated curve should be read as a visual version of the same planning relationship: as the target effect becomes smaller, the required sample size rises. It does not show the probability that the completed trial succeeded or the power observed after results were known. This is not observed power. It is a set of conditional planning illustrations based on the stated assumptions and effect scenarios, not a reconstruction of the trial’s original design process.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.444; treatment proportion p₁ = 0.714; average p̄ = 0.579.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6982 = 1.3684.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6717 = 0.5653.
4. n = (1.3684 + 0.5653)² / (0.2695)² = 51.5, rounded up to 52 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.444444444444444                          # control proportion
p1 <- 0.713987473903967                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2760407)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 52 (80% power), 69 (90% power)
 75% of observed effect: n per arm = 95 (80% power), 126 (90% power)
 50% of observed effect: n per arm = 215 (80% power), 288 (90% power)
power.prop.test: 51.5 
Simulated power at n = 52 per arm: 0.826 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The sponsor reported primary risk differences of 0.270 for q4w olokizumab versus placebo and 0.258 for q2w olokizumab versus placebo. Both were based on chi-squared analyses, used 97.5% confidence intervals, were labeled superiority, and had p < 0.001. These are the formal primary comparisons recorded by the sponsor.

The simple unadjusted re-calculations from the posted group counts give point estimates close to the sponsor’s estimates. The confidence-interval limits and p-value format are not identical, reflecting that the re-calculation is not necessarily the same procedure as the sponsor analysis. The registry does not provide enough methodological detail to identify the reason for every difference. Because the registry does not flag a discrepancy, these results are best understood as broadly consistent checks rather than conflicting primary conclusions.

The sponsor also reported a superiority comparison of adalimumab with placebo for ACR20 response and a non-inferiority analysis comparing q4w olokizumab with adalimumab. Those are secondary analyses, not replacements for the two placebo-controlled primary comparisons. The sponsor’s non-inferiority label should be read with the limitation that the margin and full decision rules are not reported in the registry record.

15. Multiplicity, Missing Data and Analysis Populations

The primary analysis population is clearly described: the intent-to-treat population includes all randomized subjects, analyzed according to their assigned group. This is an important specification because it identifies who contributes to the primary comparison and how assignment is handled. The primary endpoint also defines response as meeting ACR20 criteria while remaining on randomized treatment and in the study at Week 12.

Other details of missing-data handling are not reported in the registry record. In particular, the posted summary does not specify what happened to missing Week 12 assessments, participants who discontinued treatment, or participants who left the study before the assessment, beyond the endpoint’s requirement to remain on treatment and in the study. It does not report imputation methods, sensitivity analyses, or alternative estimands. The stated responder condition should therefore be distinguished from a complete account of missing-data procedures.

The registry lists 7 outcome measures and 19 analyses, with 6 secondary outcomes posted. Multiple comparisons can complicate interpretation because evaluating many hypotheses may increase the chance of at least one apparently positive result. The record does not report a complete multiplicity-control procedure, testing hierarchy, or family of hypotheses. The 97.5% confidence intervals and superiority labels on the two primary comparisons are reported, but their relationship to any broader multiplicity plan is not specified.

Several elements of the statistical plan are also not reported in the registry record, including the original sample-size justification, interim analyses, detailed analysis populations for all secondary outcomes, and the full method for the active-comparator non-inferiority analysis. In particular, the non-inferiority margin is not reported. Without those details, the sponsor’s labels can be described, but some design decisions and the full inferential framework cannot be independently assessed from the posted record.

These gaps do not erase the posted counts or sponsor estimates. They limit how completely the statistical procedures can be reconstructed and how confidently results across multiple analyses can be interpreted as a single coordinated body of evidence. The primary randomized comparison is the most clearly specified question in the record; secondary and non-inferiority findings require additional caution where their decision rules are not available.

16. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 4% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pneumonia (1.3%), urosepsis (0.8%), sepsis (0.4%), urinary tract infection (0.4%), interstitial lung disease (0.4%).

The registry reports serious adverse events for each group using the number at risk and the number affected. The q4w olokizumab group had 20 serious adverse events among 477 at risk; the q2w olokizumab group had 22 among 463; the adalimumab group had 26 among 462; and the placebo group had 12 among 243. Deaths reported were 2, 3, 1, and 1, respectively. These are counts in the registry record and should be read in relation to the listed group denominators.

The record also lists selected serious adverse-event terms and reported percentages: pneumonia, 1.3%; urosepsis, 0.8%; sepsis, 0.4%; urinary tract infection, 0.4%; interstitial lung disease, 0.4%; and transaminases increased, 0.4%. These are listed terms, not a complete description of every event or its clinical course.

Serious adverse events are distinct from the separately reported other adverse-event counts, which were 177, 183, 129, and 71 across the four groups in the same order. Counts alone do not establish comparative risk, causation, or the timing and duration of events. The registry record does not provide further details about event-level adjudication, exposure-adjusted rates, or statistical comparisons of safety between groups. These data describe reported safety events during the study and are not individualized medical guidance.

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

The primary result means that, under the registry’s Week 12 ACR20 definition and the intent-to-treat analysis population, the sponsor reported higher response proportions for each olokizumab regimen than for placebo. The reported risk differences were 0.270 for q4w and 0.258 for q2w, and both analyses were labeled superiority with p < 0.001. The confidence intervals provide information about the precision of those estimates under the sponsor’s methods.

It does not mean that every participant responded, that every person would have the same result, or that the two olokizumab regimens were directly shown to be equivalent. The primary analyses compare each olokizumab regimen with placebo. The registry does not report a direct primary comparison between the two olokizumab schedules. Nor do the primary results alone answer every question about comparison with adalimumab.

The endpoint has a specific composite definition and includes remaining on randomized treatment and in the study at Week 12. It does not represent all possible measures of disease activity, physical function, long-term outcomes, or safety. Some secondary results are posted, but the registry does not report numerical results for every listed secondary outcome, and the full multiplicity strategy is not reported.

The findings also do not establish how results apply to populations, treatment conditions, or time points not represented by the trial record. The record describes subjects with moderately to severely active rheumatoid arthritis inadequately controlled by methotrexate, and the listed regimens were given alongside methotrexate. Longer-term results and additional details about eligibility, missing data, and the original design assumptions are not reported in the registry record.

Finally, a statistically significant result is not itself a judgment of clinical importance. The registry does not specify a threshold for a clinically important risk difference. The posted statistics should be read as evidence about these randomized group comparisons under the stated endpoint and analysis, not as medical advice or as a guarantee of an individual outcome.

18. Why This Trial Matters Statistically

Statistically, this trial is useful because it includes randomized comparisons against both placebo and an active comparator while maintaining background methotrexate. The parallel-group, double-blind design helps define the intended contrasts and aims to limit bias from treatment assignment and treatment knowledge. The primary question is also clearly stated around a specified response outcome and Week 12 assessment.

The binary endpoint makes the main comparison interpretable on an absolute scale through risk differences. The sponsor’s estimates and confidence intervals describe both the direction and precision of the two olokizumab-versus-placebo contrasts. The arm counts allow a simple unadjusted re-calculation, offering a transparent check alongside the sponsor’s reported analysis, while the differences in intervals and p-value formats illustrate why the exact analysis method matters.

The design also creates broader interpretive questions. Multiple treatment comparisons and secondary outcomes require attention to multiplicity, while an active-comparator non-inferiority claim depends on a margin and testing rules that are not reported in the registry record. The distinction between a primary placebo comparison and secondary active-comparator analyses is therefore important when weighing the evidence.

Finally, the planning illustrations show how sample-size needs depend on the effect a future study aims to detect. They are not the original trial design rationale and are not observed power. Taken together, the record supports a focused reading of the Week 12 randomized contrasts while also showing why the analysis plan, missing-data procedures, and multiplicity strategy matter for a complete statistical assessment.

19. 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 several details needed to reconstruct the trial’s full statistical design. The original sample-size justification, interim-analysis plan, detailed multiplicity strategy, and complete statistical analysis plan are not reported. The planning figures available are illustrations based on observed effects, not the trial’s original design assumptions.

Although the primary analysis population is defined as intent-to-treat, the posted record does not give detailed missing-data rules or sensitivity analyses. The endpoint requires participants to remain on randomized treatment and in the study at Week 12, but additional handling of missing assessments and discontinuations is not described. That limits assessment of how attrition and unavailable measurements may have affected the response counts.

The record lists several secondary outcomes and analyses, but numerical results are not available for every listed outcome. The full analysis population and statistical procedures for each secondary endpoint are not all described in the posted information. Multiple testing is relevant given the number of outcomes and analyses, but the registry does not report a complete adjustment strategy or testing hierarchy.

The non-inferiority analysis comparing q4w olokizumab with adalimumab is labeled as such, but the margin and detailed decision rules are not reported. This restricts independent evaluation of that conclusion. Safety is also presented mainly as counts and selected serious event terms; further information such as event timing, exposure-adjusted comparisons, and detailed adjudication is not reported in the material available in the registry record.

Finally, the primary endpoint addresses a particular composite response at Week 12 in subjects with rheumatoid arthritis inadequately controlled by methotrexate. The record does not establish how results extend to other populations, outcomes, treatment contexts, or time horizons. These limitations concern the scope and reconstructability of the posted evidence and do not change the numerical results reported for the defined comparisons.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Evaluation of the Efficacy and Safety of Two Dosing Regimens of Olokizumab (OKZ), Compared to Placebo and Adalimumab, in Subjects With Rheumatoid Arthritis (RA) Who Are Taking Methotrexate But Have Active Disease — NCT02760407.
• Registry record last updated 2023-09-21; status last verified 2023-09.
• Results first posted 2021-04-30.
• 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.

23. Record Summary

NCT02760407 is a completed randomized, double-blind, parallel-group Phase III study of olokizumab in subjects with moderately to severely active rheumatoid arthritis inadequately controlled by methotrexate. The four groups received olokizumab 64 mg every 4 weeks, olokizumab 64 mg every 2 weeks, adalimumab 40 mg every 2 weeks, or placebo every 2 weeks, alongside methotrexate. The registry reports enrollment of 1648.

The primary endpoint was ACR20 response at Week 12, defined to include remaining on randomized treatment and in the study. The sponsor reported superiority versus placebo for both olokizumab regimens, with risk differences of 0.270 and 0.258, 97.5% confidence intervals above zero, and p < 0.001 for each comparison. Secondary outcomes include additional response, disease-activity, and function measures; not every listed outcome has posted numerical results.

The record identifies the intent-to-treat population but does not report the full statistical plan, detailed missing-data procedures, multiplicity strategy, or original sample-size justification. Safety information includes serious-event and death counts by group and selected serious event terms. The posted data should be interpreted within the study’s population, Week 12 endpoint, and reported comparisons.