A Placebo-controlled Phase 2 Trial to Investigate the Safety and Efficacy of Secukinumab in Giant Cell Arteritis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Placebo-controlled Phase 2 Trial to Investigate the Safety and Efficacy of Secukinumab in Giant Cell Arteritis (NCT03765788), a randomized phase 2 study. The primary outcome is Percentage of Participants in Sustained Remission Until Week 28.

2. Clinical Question

The trial was designed to investigate both efficacy and safety, including maintenance of remission during corticosteroid tapering through Week 28 and follow-up through 52 weeks. The primary endpoint addresses whether participants remained free of a flare while following the planned taper. This is a joint clinical and protocol-based outcome: absence of flare alone was not enough if the participant did not adhere to the tapering regimen.

The question is comparative, but the registry record describes a relatively small phase 2 study. Its results therefore need to be read as estimates from this trial rather than as a definitive answer for every person with giant cell arteritis. The endpoint definition, analysis population, and rules for classifying participants who did not complete or could not be assessed all affect what the reported counts mean.

3. Trial Design

This was a randomized, parallel-group, double-blind, placebo-controlled, multicenter phase 2 trial. The registry record lists an enrollment of 52 participants and a completed study. The trial began on 2019-01-30, and primary completion was recorded on 2021-06-08. The sponsor was Novartis Pharmaceuticals.

Participants were assigned to secukinumab or placebo. Both groups also received a 26-week prednisolone tapering regimen. Secukinumab was administered as a 300 mg subcutaneous injection at Baseline and Weeks 1, 2, 3, and 4, then every 4 weeks through Week 48. The placebo arm followed the corresponding injection schedule. The treatment schedules mean the comparison concerns adding the assigned injection regimen to a shared prednisolone taper, not secukinumab in the absence of corticosteroids.

The primary analysis included 27 participants in the secukinumab arm and 25 in the placebo arm. This is consistent with the registry definition of the Full Analysis Set, which included randomized participants who received at least one dose of assigned study treatment. The endpoint classified participants as non-responders under several circumstances, including failure to achieve remission within 12 weeks of Baseline, entering the escape arm before Week 28, early discontinuation of study treatment before Week 28, or lack of information needed to evaluate sustained remission.

The registry record does not report the original sample-size justification or the detailed statistical plan for the trial. It also does not report the method used for randomization, the allocation concealment procedure, or additional operational details of blinding. These details should not be inferred from the randomized, double-blind labels alone.

The study included secondary outcomes addressing remission at Week 12, time to first flare after clinical remission, cumulative prednisolone dose, remission through Week 52, prednisolone dose, physician and patient assessments, and fatigue. The registry lists 13 outcome measures and one analysis. Details of which other planned analyses were conducted 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.

Before assignment: The screening period began once patients had signed the study informed consent. Screening evaluations were performed up to 6 weeks before the beginning of the Treatment period.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Full Analysis Set (FAS) comprised all patients to whom study treatment had been assigned by randomization and who received at least one dose of randomized study treatment (secukinumab or placebo).

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: The Full Analysis Set (FAS) comprised all patients to whom study treatment had been assigned by randomization and who received at least one dose of randomized study treatment (secukinumab or placebo).

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants in Sustained Remission Until Week 28, measured over Until week 28.

The primary endpoint is the number and percentage of participants in sustained remission until Week 28. Remission was defined as absence of a flare. Sustained remission required absence of flare through Week 28 while adhering to the protocol prednisolone taper regimen. The outcome therefore captures a course over time, rather than a single assessment at the end of the period.

A flare was determined by the investigator. It was defined as recurrence after remission of signs or symptoms of giant cell arteritis, and/or an erythrocyte sedimentation rate of at least 30 mm/hr, and/or C-reactive protein of at least 10.0 mg/L attributable to giant cell arteritis. Because the definition allows clinical signs or symptoms and inflammatory-marker criteria, it combines investigator assessment with laboratory information.

This endpoint is used to assess whether remission is maintained while corticosteroids are tapered. That focus matters to the trial question because the study was designed to evaluate remission maintenance alongside corticosteroid tapering. However, the endpoint is not simply the presence or absence of symptoms at Week 28: adherence to tapering and the specified non-responder rules also contribute to the classification.

Participants were classified as non-responders if they did not reach remission within 12 weeks of Baseline, entered the escape arm between Baseline and Week 28, discontinued study treatment early, or lacked information to assess sustained remission through Week 28. The posted counts therefore reflect the endpoint’s full classification rule, not only observed flares among participants with complete follow-up.

7. Results Posted in the Registry

• Secukinumab: 70.4% (19/27) versus 24.0% (6/25) on control; risk difference 46.4 percentage points (95% CI 22.4 to 70.4), risk ratio 2.93 (1.40–6.14); 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 Participants in Remission at Week 12

• 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:
  • Secukinumab: 81.5% (22/27) versus 48.0% (12/25) on control; risk difference 33.5 percentage points (95% CI 9.0 to 57.9), risk ratio 1.70 (1.09–2.65); unadjusted two-proportion z-test p = 0.011.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Secukinumab than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Percentage of Participants With GCA Who Had Sustained Remission Until Week 52

• 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:
  • Secukinumab: 59.3% (16/27) versus 8.0% (2/25) on control; risk difference 51.3 percentage points (95% CI 29.9 to 72.6), risk ratio 7.41 (1.89–29.02); 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 Secukinumab than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The two secondary remission outcomes with numeric results show a pattern in the same direction as the primary endpoint: more participants in the secukinumab arm met the remission criteria at the reported follow-up points. This provides related evidence about remission at an earlier assessment and sustained remission over a longer period, but these outcomes are not interchangeable with sustained remission through Week 28. Their definitions and time horizons differ, so they complement rather than replace the primary result.

The registry also lists secondary outcomes concerning time to first flare after clinical remission, cumulative prednisolone dose over 28 and 52 weeks, prednisolone dose, physician and patient assessments of disease activity, and fatigue. Numeric results for most of these listed outcomes are not reported in the registry record. As a result, the broader pattern across steroid use, flare timing, assessments, and fatigue cannot be determined from the posted results. A consistent direction across the two reported remission measures should not be taken to imply that every secondary outcome followed the same pattern.

The posted secondary comparisons are unadjusted. When several outcomes are evaluated, the chance of at least one apparently notable result due to chance can increase unless the analysis plan addresses multiplicity. The registry record does not report a multiplicity-control strategy. For that reason, secondary findings generally carry less weight than a prespecified primary result and should be interpreted as supportive or exploratory, especially when many outcomes were assessed and the adjustment plan is unknown.

Secondary outcomes can still help characterize different aspects of the trial question. Remission at an earlier time point, sustained remission at a later time point, steroid exposure, flare timing, and patient- or physician-reported assessments each address a different dimension. Their usefulness depends on clear definitions, complete reporting, and appropriate consideration of multiple testing. The registry’s limited numeric reporting prevents a comprehensive assessment across all listed domains.

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

• Percentage of Participants in Remission at Week 12
• Time to First GCA Flare After Clinical Remission
• Total Cumulative Prednisolone Dose Over 28 Weeks and 52 Weeks
• Percentage of Participants With GCA Who Had Sustained Remission Until Week 52
• Number of Participants on Prednisolone Dose ≤ 5mg/Day
• Physicians Global Assessment (PhGA) of Disease Activity: Change From Baseline Score Via Visual Analogue Scale (VAS)
• Patients Global Assessment (PGA) of Disease Activity: Change From Baseline Via Visual Analogue Scale (VAS)
• Change From Baseline in FACIT-Fatigue Scale

9. Statistical Interpretation

10. Statistical Methods Explained

General statistical explanation: a randomized comparison aims to make the treatment groups comparable on average at the point of assignment. Randomization can reduce systematic differences between groups, while masking can reduce the influence of expectations on care and assessment. These design features do not eliminate chance variation, missing data, or limitations in how outcomes are defined and measured. The registry identifies the study as randomized and double-blind but does not report the detailed procedures used to implement these features.

What does a binary endpoint mean?

General statistical explanation: a binary endpoint classifies each participant into one of two categories, such as meeting or not meeting a response definition. The registry’s primary outcome is reported as counts of participants meeting sustained remission criteria. The arm counts are 19 of 27 for secukinumab and 6 of 25 for placebo. Interpreting these counts requires attention to the registry’s definition of sustained remission and its rules for treating participants without a qualifying assessment as non-responders.

A comparison of proportions can be expressed in several ways. A risk difference subtracts the proportion in one arm from the proportion in the other, describing an absolute contrast. A risk ratio compares the proportions as a ratio, and an odds ratio compares the odds of the outcome. These are distinct summaries and can have different numerical magnitudes. For the primary endpoint, the posted recalculation gives a risk difference of 0.464 and a risk ratio of 2.932; its odds-ratio calculation is 7.521. These are unadjusted calculations from the posted summary counts. The sponsor reports an odds ratio from its own analysis, discussed separately.

What does the p-value convey?

General statistical explanation: a p-value summarizes how unusual data at least as incompatible with a specified null hypothesis would be if that null hypothesis and the analysis assumptions were correct. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. The posted primary recalculation gives an unadjusted p-value of <0.001. The word unadjusted matters: it describes the recalculation as posted and does not establish that it accounts for other outcomes, covariates, or analysis choices. The registry record does not report a complete statistical analysis plan that would clarify all planned inferential procedures.

How should intervals be read?

General statistical explanation: a confidence interval gives a range of estimates compatible with the data under a particular method. A narrower interval indicates greater precision for that estimate, while a wider interval reflects more uncertainty. An interval is not a list of all possible true values, and its interpretation depends on the method and assumptions used to construct it. The recalculated risk-difference interval for the primary endpoint is 0.224 to 0.704. The sponsor reports a 95% interval for its odds ratio. The confidence level for the recalculated risk-difference interval is not stated in the registry information summarized for this result, so it should not be assumed.

The reported effect measure also determines what an interval means. A risk-difference interval is on the absolute-proportion scale; an odds-ratio interval is on the odds scale. The endpoints of an interval should be read with the estimate and measure together, not as standalone values. An interval that excludes the null value for its measure is evidence against that null under the calculation’s assumptions, but it does not resolve limitations such as missing data, multiplicity, or generalizability.

Why do the endpoint rules matter?

The primary outcome counts sustained remission only when absence of flare is maintained through Week 28 and the participant adheres to the protocol taper. The flare definition combines investigator-determined recurrence of signs or symptoms with specified inflammatory-marker thresholds when attributable to giant cell arteritis. Consequently, classification may depend on clinical assessment, laboratory information, timing, and treatment adherence.

Participants who did not achieve remission within 12 weeks of Baseline were classified as non-responders. The same applied to participants entering the escape arm before Week 28, those who discontinued treatment before Week 28, and those without information to evaluate the response through Week 28. Such rules can preserve a clear assigned-group comparison and avoid counting unobserved outcomes as successes, but they also mean the endpoint combines disease status with study-course events. The registry does not report further sensitivity analyses exploring alternative missing-data assumptions.

What is and is not known about the analysis?

The registry states that the Full Analysis Set comprised randomized participants who received at least one dose of assigned treatment. This population is broader than a population restricted to participants who completed all treatment and assessments, but it is not identical to every randomized participant if someone was assigned treatment and never received a dose. The reported arm denominators, 27 and 25, are the denominators for the posted primary results.

The registry record does not report the original sample-size justification, the trial’s detailed statistical analysis plan, any multiplicity-control procedure, or whether interim analyses were planned or conducted. Those omissions do not mean that such procedures were absent; they mean they cannot be described from the registry record. The posted recalculation is a simple unadjusted recalculation from summary statistics and should be distinguished from the sponsor’s own reported analysis.

General statistical explanation: over-dispersion is a concern when observed variation is greater than a statistical model assumes. It can make standard errors too small if ignored, which in turn can make intervals too narrow and p-values too small. That issue is more commonly central for count or clustered outcomes than for a simple binary summary. The primary endpoint is reported as participant counts, and the registry does not report a model-based analysis or a specific over-dispersion assessment. It would therefore be inappropriate to claim that such an adjustment was made or required for the sponsor’s analysis.

Likewise, a method label such as logistic regression, covariate adjustment, or stratification cannot be inferred from the odds-ratio result alone. The sponsor’s method field is not reported in the registry record. Without that detail, the sponsor result can be described as the reported odds ratio and interval, but its precise model and adjustment set cannot be reconstructed from the posted summary.

11. Confidence Intervals and Precision

For the primary outcome, the recalculated risk difference is 0.464, with an interval from 0.224 to 0.704. The interval is a measure of precision for the absolute contrast: it indicates a range of estimates compatible with the data and calculation method, rather than pinning down a single exact effect. Its width reflects uncertainty that remains even though the observed arm proportions are separated.

The observed counts are based on 27 participants in the secukinumab arm and 25 in the placebo arm. With a relatively small number of participants, the estimate can be sensitive to the outcome classification of individual participants. The endpoint’s rules add another interpretive layer because early discontinuation, escape-arm entry, failure to achieve remission within 12 weeks, and missing assessment information all result in non-responder classification.

The sponsor reports an odds ratio of 9.31 with a 95% confidence interval from 3.54 to 26.29. The recalculated unadjusted odds ratio is 7.521, with an interval from 2.188 to 25.85. These summaries use the same general odds scale but are not identical analyses: the sponsor’s method is not reported in the registry record, while the recalculation is an unadjusted calculation from the posted summary counts. The registry marks no discrepancy between the posted analysis and recalculation. The sponsor’s own analysis remains the trial’s reported analysis.

The risk-difference interval and odds-ratio interval should not be compared directly by their numeric width because they are on different scales. The reported estimates support a direction of difference in this sample, but the exact magnitude remains uncertain. Precision is also distinct from generalizability: even a relatively narrow interval would not show that the result applies to populations beyond the study eligibility and conduct.

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 based on the observed effect, not the trial’s original design justification. For these binary outcomes, the figures are participants per arm, not total events. The planning assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is set as the stated fraction of the observed effect.

The 80% power column describes the number of participants per arm that the illustration estimates would be needed for an 80% chance of detecting the chosen effect under those assumptions, if that effect were the true one and the assumptions held. The 90% power column gives the corresponding planning count for a higher target chance of detection. These are design calculations, not statements about what happened in the completed trial.

Rows planning for 100%, 75%, or 50% of the observed effect ask what the sample size might look like if a future study aimed to detect the full observed contrast or a smaller fraction of it. Smaller effects are harder to distinguish from chance variation, so the corresponding planning illustrations require more participants per arm. The estimates are sensitive to the observed effect used as their starting point; a large observed effect in a small trial can make a planning illustration look more optimistic than a future study would warrant.

This is not observed power. Observed power is not a useful substitute for interpreting the estimate and its interval after the trial. The planning figures instead illustrate how assumed effect size and target power relate to sample size under the stated calculation assumptions. The trial’s original sample-size assumptions are not reported in the registry record.

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 = 0.240; treatment proportion p₁ = 0.704; average p̄ = 0.472.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7060 = 1.3837.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6252 = 0.5262.
4. n = (1.3837 + 0.5262)² / (0.4637)² = 17.0, rounded up to 17 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 <- 0.24                          # control proportion
p1 <- 0.703703703703704                          # 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(3765788)
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 = 17 (80% power), 23 (90% power)
 75% of observed effect: n per arm = 31 (80% power), 41 (90% power)
 50% of observed effect: n per arm = 66 (80% power), 88 (90% power)
power.prop.test: 17 
Simulated power at n = 17 per arm: 0.821 (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’s reported primary analysis is an odds ratio of 9.31, with a 95% confidence interval from 3.54 to 26.29. The registry classifies this as a superiority analysis. No p-value is reported alongside that result, and the method used to estimate the odds ratio is not reported in the registry record.

The posted unadjusted recalculation from the summary counts gives an odds ratio of 7.521, with an interval from 2.188 to 25.85. It also expresses the comparison as a risk difference of 0.464, with an interval from 0.224 to 0.704, and an unadjusted p-value of <0.001. These summaries should not be collapsed into one estimate: the risk difference and odds ratio use different scales, and the recalculation is not a reconstruction of an undocumented sponsor model.

The registry does not flag a discrepancy between the reported analysis and the recalculation. The sponsor’s result is the trial’s own reported analysis, while the recalculation is a simple, unadjusted check using posted counts. Because the sponsor’s method and any adjustments are not reported in the registry record, differences in the numerical odds-ratio estimates cannot be attributed to a specific modeling choice. Both summaries show a higher observed outcome in the secukinumab arm, but the sponsor analysis and the recalculation should remain clearly distinguished.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study assesses several outcomes, time points, or comparisons. In general, the more statistical questions asked, the greater the chance that at least one result will appear unusual by chance alone. A prespecified testing hierarchy or other adjustment can address this issue, but the registry record does not report whether a multiplicity-control procedure was planned or used. The primary endpoint is clearly identified, while the registry lists multiple secondary outcomes; unadjusted secondary p-values should therefore be interpreted cautiously.

The posted primary recalculation gives an unadjusted p-value of <0.001. This describes that calculation and does not show whether the sponsor’s complete analysis plan included adjustment or a testing sequence. The sponsor’s reported primary odds ratio has no p-value posted in the registry record. The record does not report whether interim analyses were planned or conducted, so no claim about interim monitoring or any resulting adjustment can be made.

Missing information is especially relevant because the endpoint definition specifies how some incomplete or interrupted participant courses are classified. Participants without information to evaluate sustained remission through Week 28 were classified as non-responders, as were participants who discontinued study treatment before Week 28 or entered the escape arm before Week 28. Participants who failed to achieve remission within 12 weeks were also classified as non-responders. These are endpoint rules, not evidence that all missing values were handled in the same way in every other outcome.

The Full Analysis Set included randomized participants who received at least one dose of assigned study treatment. The registry record does not report the number of randomized participants who received no dose, further details about exclusions, or sensitivity analyses that test alternative assumptions about missing outcomes. Nor does it provide a detailed account of missing data for the secondary endpoints.

These reporting gaps limit independent assessment of the analysis choices. They do not establish that a procedure was omitted; they mean that the procedure is not reported in the registry record. Conclusions should stay tied to the defined analysis population, the stated endpoint rules, and the posted estimates rather than assuming additional adjustments or robustness checks.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: atrial fibrillation (4.0%), atrial tachycardia (4.0%), cardiac failure (4.0%), gastrointestinal pain (4.0%), melaena (4.0%).

The registry reports serious adverse events in 6 of 27 participants at risk in the secukinumab arm and 11 of 25 at risk in the placebo arm. It reports other adverse events in 25 of 27 and 23 of 25 participants, respectively. One death is reported in each arm. These counts describe the registry’s recorded safety outcomes; they do not by themselves establish whether an event was caused by the assigned treatment.

The listed serious-event terms each have a reported frequency of 4.0%: atrial fibrillation, atrial tachycardia, cardiac failure, gastrointestinal pain, melaena, and general physical health deterioration. The registry record does not provide enough detail to infer the timing, duration, severity beyond the serious-event classification, or treatment attribution for each term. The listed terms should not be assumed to be mutually exclusive or to account for every serious event unless the registry explicitly says so.

Safety comparisons in a trial of this size are imprecise, particularly for individual event types. The counts are useful for describing what was recorded during the study, but they are not a definitive estimate of comparative safety or evidence of causation. The registry’s aggregate event figures should be interpreted alongside the design and follow-up rather than as standalone treatment conclusions.

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

The primary result describes the proportion of participants meeting a particular sustained-remission definition during this randomized trial. Under that definition, more participants in the secukinumab arm than in the placebo arm met the endpoint through Week 28. The posted unadjusted contrast and its interval quantify the observed difference and uncertainty for this sample. The sponsor’s reported odds ratio is a separate analysis summary and should be read on the odds scale.

This result does not mean every participant receiving secukinumab achieved remission, nor that a participant’s outcome can be predicted from the group average. It also does not establish what would happen under a different corticosteroid regimen, treatment schedule, eligibility criteria, or follow-up period. Both arms received a prednisolone taper, so the comparison concerns the assigned injection regimen in that setting.

The endpoint combines absence of flare with adherence to the protocol taper, and the registry classifies some participants as non-responders based on early discontinuation, escape-arm entry, failure to reach remission within 12 weeks, or unavailable assessment information. Thus the outcome is not a pure measure of biological disease activity isolated from study conduct. The investigator-determined flare definition and laboratory thresholds also shape the result.

The findings do not establish that secukinumab is safe or unsafe in general. Serious adverse event counts, other adverse event counts, and deaths are descriptive trial data, and they do not establish causation. The study’s enrollment and the lack of detailed event-level information limit what can be inferred about uncommon events or comparative risk.

Nor do the secondary results settle the overall evidence across steroid exposure, flare timing, or patient and physician assessments. Numeric results are not reported for most listed secondary outcomes, and a multiplicity strategy is not reported. The appropriate interpretation is therefore narrow: a higher observed count meeting the defined primary endpoint in the secukinumab arm in this trial, with uncertainty and limitations that remain important.

18. Why This Trial Matters Statistically

This trial is statistically informative because it connects a randomized treatment comparison to a clinically structured endpoint: sustained remission during a prednisolone taper. The endpoint makes clear that remission maintenance is not just a status at one visit; it requires absence of flare over time while following the specified taper. That definition helps readers understand what the primary count represents and why participant classification rules matter.

The posted results also illustrate why effect measures should be kept distinct. A risk difference communicates an absolute contrast, while an odds ratio describes a comparison on the odds scale. The sponsor’s reported odds ratio and the unadjusted recalculation provide related but not identical summaries. Reading both alongside the arm counts and intervals is more informative than focusing on a single p-value.

The registry record highlights the importance of transparency about analysis planning. The original sample-size justification, detailed statistical plan, missing-data sensitivity analyses, multiplicity strategy, and interim-analysis information are not reported. Those details matter because they help distinguish confirmatory inference from exploratory findings and clarify how uncertainty was handled.

Finally, the limited number of participants and the incomplete numeric reporting across secondary outcomes show why statistical interpretation must combine estimates, precision, design, endpoint definitions, and reporting completeness. A result can be noteworthy without answering every question about durability, steroid exposure, safety, or generalizability. The trial is a useful example of reading a favorable-looking observed contrast without converting it into a broader treatment claim.

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 enrollment was 52, with 27 participants in the primary secukinumab analysis and 25 in the placebo analysis. This limits precision, particularly for safety outcomes and less frequent events. The interval around the primary risk difference is compatible with a range of effect sizes, so the observed contrast should not be treated as an exact estimate.

The primary endpoint depends on a compound definition involving investigator-determined flare, inflammatory-marker thresholds, adherence to a prednisolone taper, and specified non-responder rules. Classification as a non-responder for early treatment discontinuation, escape-arm entry, failure to achieve remission within 12 weeks, or insufficient information can make the result sensitive to study-course events as well as disease status.

The sponsor’s odds-ratio method is not reported in the registry record. The original sample-size justification, detailed statistical analysis plan, multiplicity approach, interim-analysis information, and missing-data sensitivity analyses are also not reported. These gaps restrict independent evaluation of how the sponsor’s analysis was specified and how robust the conclusions are to alternative assumptions.

Only two secondary remission outcomes have numeric results in the registry information; numeric findings for most other listed secondary outcomes are not reported in the registry record. This prevents a full assessment of consistency across steroid exposure, flare timing, fatigue, and patient- or physician-reported disease activity. Unadjusted secondary findings also require caution when the multiplicity strategy is unknown.

The registry describes a population with newly diagnosed or relapsing giant cell arteritis who were naïve to biological therapy. Results should not automatically be generalized beyond the study population, intervention schedules, and shared prednisolone taper. Safety counts are descriptive and do not establish causation.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: A Placebo-controlled Phase 2 Trial to Investigate the Safety and Efficacy of Secukinumab in Giant Cell Arteritis — NCT03765788.
• Registry record last updated 2023-08-21; status last verified 2023-08.
• Results first posted 2023-04-26.
• 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

The registry record describes a completed, randomized, double-blind, parallel-group, placebo-controlled, multicenter phase 2 trial of secukinumab in giant cell arteritis. Enrollment was 52. Participants received secukinumab or placebo alongside a 26-week prednisolone tapering regimen.

The primary outcome was sustained remission through Week 28, defined by absence of flare while adhering to the protocol taper. The Full Analysis Set included randomized participants who received at least one dose of assigned treatment. The posted results report 19 of 27 participants meeting the endpoint in the secukinumab arm and 6 of 25 in the placebo arm. The sponsor reports an odds ratio of 9.31 with a 95% confidence interval from 3.54 to 26.29; an unadjusted recalculation from the summary counts gives a risk difference of 0.464 with an interval from 0.224 to 0.704.

Secondary remission results are also posted for Week 12 and Week 52, while numeric results for most other listed secondary outcomes are not reported in the registry record. Safety results include serious and other adverse events and one death in each arm. Important details about the original sample-size justification, statistical plan, multiplicity, and further missing-data analyses are not reported in the registry record.