Evaluation of Efficacy and Safety of Sarilumab in Patients With GCA: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Efficacy and Safety of Sarilumab in Patients With GCA (NCT03600805), a randomized phase 3 study. The primary outcome is Percentage of Participants Who Achieved Sustained Disease Remission at Week 52.

2. Clinical Question

The registry describes this as a randomized, quadruple-masked, parallel-group Phase 3 study. It lists 83 participants enrolled and a terminated status. The primary objective was to evaluate sustained remission with sarilumab versus placebo in combination with corticosteroid tapering. The secondary objectives included clinical responses over time, cumulative corticosteroid exposure, safety and tolerability, serum concentrations, and glucocorticoid toxicity. The posted primary comparison is specifically between the 200 mg sarilumab group with a 26-week taper and the placebo group with a 52-week taper; it should be interpreted as a comparison of those treatment regimens, not as a comparison in which taper duration was held constant.

3. Trial Design

The registry identifies this as a randomized, quadruple-masked, parallel-group Phase 3 study of sarilumab in people with giant cell arteritis. The listed interventions include sarilumab, sarilumab-matching placebo, prednisone, and prednisone-matching placebo. The arm descriptions specify sarilumab or matching placebo every 2 weeks, alongside protocol-scheduled prednisone and matching placebo. The registry record gives an enrollment of 83 and a status of terminated. The study start is listed as 2018-11-20, and primary completion as 2020-11-24. A reason for termination is not reported in the registry record.

Four treatment groups appear in the primary outcome results: placebo with a 52-week taper, placebo with a 26-week taper, sarilumab 150 mg every 2 weeks with a 26-week taper, and sarilumab 200 mg every 2 weeks with a 26-week taper. The primary comparison is between the 200 mg sarilumab group and placebo with the 52-week taper. Thus, the compared groups differ in assigned study drug and taper schedule. The registry lists the primary outcome population as the Week 52 analysis set, consisting of randomized participants who had the opportunity to complete the 52-week treatment period; the record defines that group by randomization before October 16th, 2019.

The posted primary outcome is a percentage, and the arm summaries give the number analyzed and the percentage achieving sustained remission. The record lists 22 outcome measures and 20 posted secondary outcomes, but comparative analyses for the posted results are not reported in the registry record. The registry does not report the original sample-size justification, the planned statistical analysis methods, the approach to missing data, or the reason the study was terminated. These absences limit what can be concluded about how the study was intended to handle design and analysis decisions.

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: Participants were randomized to 4 treatments arms in 2:1:1:2 ratio by interactive response technology stratified by starting dose of prednisone at Baseline (less than \[\<\] 30 milligrams per day (mg/day) or greater than or equal to \[\>=\] 30 mg/day).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis was performed on Week 52 analysis set population that included randomized participants who had opportunity to complete the 52-week treatment period (randomized prior to October 16th, 2019).

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: Analysis was performed on randomized population.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants Who Achieved Sustained Disease Remission at Week 52, measured over At Week 52.

The primary endpoint is the percentage of participants who achieved sustained disease remission at Week 52. The registry defines remission as resolution of GCA signs and symptoms together with normalization of C-reactive protein (CRP) to <10 mg/L. Sustained remission requires several conditions: remission must be achieved no later than Week 12; disease flare must be absent from Week 12 through Week 52; CRP must remain normalized over that interval, without successive elevations to >=10 mg/L; and participants must successfully adhere to the prednisone taper over that interval.

This is a composite outcome: meeting the endpoint depends on satisfying all of its specified components, rather than only having a favorable result on one measure. It therefore reflects disease signs and symptoms, an inflammatory marker, flare status, and adherence to the taper together. A participant who meets some components but not all does not meet the stated sustained-remission definition.

The registry uses this outcome to address the primary objective of evaluating sarilumab in combination with corticosteroid tapering. Requiring sustained remission over time makes the endpoint distinct from remission at a single visit. It also makes the result dependent on the taper-related component, so the treatment-regimen context matters when interpreting group differences. The primary population is the Week 52 analysis set, not the full enrollment figure. The registry does not report the primary endpoint’s missing-data handling or an alternative endpoint definition.

7. Results Posted in the Registry

• Sarilumab 200mg q2w+26 Week Taper: 46.2% (6/13) versus 30.0% (3/10) on control; risk difference 16.2 percentage points (95% CI -23.1 to 55.4), risk ratio 1.54 (0.50–4.69); unadjusted two-proportion z-test p = 0.431.

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.

Number of Participants With Achievement of Disease Remission up to Week 12: Week 52 Analysis Set

• 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:
  • Sarilumab 200mg q2w+26 Week Taper: 53.8% (7/13) versus 70.0% (7/10) on control; risk difference -16.2 percentage points (95% CI -55.4 to 23.1), risk ratio 0.77 (0.40–1.47); unadjusted two-proportion z-test p = 0.431.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sarilumab 200mg q2w+26 Week Taper and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants With Achievement of Disease Remission up to Week 12: Intent-to-treat (ITT) Population

• 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:
  • Placebo+26 Week Taper: 42.9% (6/14) versus 57.1% (16/28) on control; risk difference -14.3 percentage points (95% CI -46.0 to 17.5), risk ratio 0.75 (0.38–1.49); unadjusted two-proportion z-test p = 0.382.
  • Sarilumab 150mg q2w+26 Week Taper: 64.3% (9/14) versus 57.1% (16/28) on control; risk difference 7.1 percentage points (95% CI -23.9 to 38.2), risk ratio 1.13 (0.68–1.86); unadjusted two-proportion z-test p = 0.657.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Placebo+26 Week Taper and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sarilumab 150mg q2w+26 Week Taper and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants With Absence of Disease Flare From Week 12 Through Week 52: Week 52 Analysis Set

• 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:
  • Sarilumab 200mg q2w+26 Week Taper: 53.8% (7/13) versus 70.0% (7/10) on control; risk difference -16.2 percentage points (95% CI -55.4 to 23.1), risk ratio 0.77 (0.40–1.47); unadjusted two-proportion z-test p = 0.431.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sarilumab 200mg q2w+26 Week Taper and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover related but distinct aspects of disease activity and treatment: achievement of remission by Week 12, absence of flare during later intervals, CRP normalization, adherence to the prednisone taper, cumulative corticosteroid exposure, safety, serum concentrations, and glucocorticoid toxicity. The posted secondary data include some remission and flare results in both the Week 52 analysis set and the intent-to-treat population. These outcomes can help describe the components and time course relevant to the primary sustained-remission definition, but they are not interchangeable with the primary composite endpoint.

Across the posted binary results, the group patterns are not uniformly in one direction. The primary percentages favor a higher observed proportion in the sarilumab 200 mg plus 26-week taper group than in the placebo plus 52-week taper group, while the Week 52 analysis-set count for remission by Week 12 is equal in those groups. Other posted results include different group and population contrasts. The displayed secondary results therefore do not independently settle the uncertainty in the primary comparison, especially because populations, outcome definitions, and follow-up intervals differ.

The registry lists 20 posted secondary outcomes, but comparative analyses are not reported in the registry record. Some recalculated comparisons are available from the posted summaries, and their unadjusted p-values should be viewed as exploratory descriptions rather than as sponsor-confirmed tests. When multiple outcomes are examined, the opportunity for chance findings increases unless a strategy for multiplicity is specified and applied. The multiplicity strategy and any hierarchy for secondary outcomes are not reported in the registry record.

The secondary outcomes are most useful as context for what was measured and how the observed results varied across measures. They should not be counted as a set of independent confirmations: several are conceptually related, use overlapping participants, or assess parts of the primary endpoint. Nor should a difference in one secondary measure be taken as proof of a difference in sustained remission. The primary result remains uncertain, and the secondary results do not remove the limits imposed by the small analysis groups, differing taper schedules, and unreported analysis details.

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

• Number of Participants With Achievement of Disease Remission up to Week 12: Week 52 Analysis Set
• Number of Participants With Achievement of Disease Remission up to Week 12: Intent-to-treat (ITT) Population
• Number of Participants With Absence of Disease Flare From Week 12 Through Week 52: Week 52 Analysis Set
• Number of Participants With Absence of Disease Flare From Week 12 Through Week 24: ITT Population
• Number of Participants With Normalization of C-Reactive Protein From Week 12 Through Week 52: Week 52 Analysis Set
• Number of Participants With Normalization of C-Reactive Protein (CRP) From Week 12 Through Week 24: ITT Population
• Number of Participants With Successful Adherence to the Prednisone Taper From Week 12 Through Week 52: Week 52 Analysis Set
• Number of Participants With Successful Adherence to the Prednisone Taper From Week 12 Through Week 24: ITT Population

9. Statistical Interpretation

10. Statistical Methods Explained

What does the percentage measure?

A percentage endpoint expresses the share of participants in an analysis group who meet a defined outcome. Here, the outcome is sustained remission, a composite requiring remission by Week 12, no flare from Week 12 through Week 52, continuing CRP normalization, and successful prednisone-taper adherence. The arm percentages therefore summarize the proportion meeting the full definition, not the proportion meeting any one component. The numbers analyzed in the primary outcome are 10 for placebo plus a 52-week taper and 13 for sarilumab 200 mg every 2 weeks plus a 26-week taper.

For a binary outcome such as meeting or not meeting the endpoint, a risk difference compares the two group proportions by subtraction. A positive risk difference in the posted comparison is oriented toward a higher observed proportion in the sarilumab 200 mg group; a negative value would be oriented toward a higher proportion in the placebo group. The registry’s recalculated risk-difference interval includes both negative and positive values. This indicates that the observed data do not tightly locate the contrast on one side of no difference.

What does the p-value say?

The posted p-value for the primary comparison is an unadjusted re-calculation from the group summaries. In general, a p-value measures how unusual data at least as discrepant as those observed would be under a specified null hypothesis and the calculation’s assumptions. It is not the probability that the null hypothesis is true, and it does not quantify the clinical importance of an effect. The registry record does not report a sponsor-conducted comparative analysis for this endpoint, so the recalculated value should not be mistaken for a reported trial-model result. The original analysis plan and its testing threshold are not reported in the registry record.

In general, an unadjusted analysis considers a comparison without accounting for the fact that many outcomes or comparisons may be examined. When many hypotheses are tested, the chance of at least one apparently unusual result can increase. That is why isolated unadjusted results, especially among secondary endpoints, are normally interpreted cautiously. The registry record does not report a multiplicity adjustment or a prespecified hierarchy for interpreting these outcomes.

Why is the confidence interval important?

In general, a confidence interval gives a range of effect estimates compatible with the observed data under the method used to construct it. It conveys precision as well as direction. A narrow interval indicates more precise estimation; a wide interval indicates that substantially different effects remain compatible with the data. For this primary comparison, the interval crosses no difference, and the group sizes are small. The interval therefore does not establish a clear direction or a precise magnitude for the between-regimen contrast. It should not be read as a guarantee that the true effect lies within its bounds.

The registry also lists relative measures for the primary comparison, but the interpretation focuses on the risk difference because it describes the contrast in group proportions directly. Relative measures can be especially unstable when based on small groups or sparse binary outcomes. General statistical practice is to consider the estimate, its interval, the outcome definition, and the analysis population together rather than treating one statistic as decisive.

What are the analysis populations?

The primary outcome uses the Week 52 analysis set, defined in the record as randomized participants with an opportunity to complete the 52-week treatment period. That opportunity is operationalized as randomization before October 16th, 2019. The record also reports some secondary outcomes in an intent-to-treat population and others in the Week 52 analysis set. These populations answer related but not identical questions. An intent-to-treat analysis generally retains participants according to randomized assignment, while the Week 52 analysis set restricts inclusion to those meeting the stated opportunity-to-complete criterion. The registry does not report the exact analysis rules for every outcome or how participants with incomplete data were handled.

Different population definitions can change both the denominators and the interpretation of a result. Comparing results across populations or time windows is not equivalent to repeating the same analysis. In this record, the primary endpoint’s analysis set is smaller than the enrollment figure, and the secondary remission results include both a Week 52 analysis set and an intent-to-treat population. Those distinctions should be kept in view when looking across the posted outcomes.

What does the sample-size illustration represent?

The sample-size figures are planning illustrations based on observed effects, not the original study design. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning row considers detecting a stated fraction of the observed effect. For these non-time-to-event outcomes, figures are participants per arm. The illustrations do not show the number enrolled in this trial or the number analyzed in the posted endpoint. They also do not indicate the probability that the completed study detected an effect. The registry’s original sample-size assumptions and justification are not reported.

These explanations describe general statistical concepts. The registry record does not report enough detail to determine whether its original analysis used the same methods as the recalculations, how protocol deviations were handled, or how missing outcome data were treated.

11. Confidence Intervals and Precision

The primary endpoint percentages are based on small analysis groups: 10 participants in the placebo plus 52-week taper group and 13 in the sarilumab 200 mg plus 26-week taper group. The observed sustained-remission proportions were 30.0% and 46.2%, respectively. With small groups, each participant’s outcome can have a noticeable influence on the group percentage, so these figures should not be treated as precise estimates of the underlying proportions.

The recalculated confidence interval for the risk difference extends from -0.231 to 0.554 in the registry calculations, but the upper endpoint has more than three decimal places and is therefore not reproduced numerically. The interval crosses zero: it is compatible with a contrast in either direction, including no difference. Its breadth indicates considerable uncertainty around the estimated contrast. The point estimate alone would give an incomplete account because it does not convey this uncertainty.

In general, a confidence interval describes the range of values compatible with the data and the method used, under its assumptions. It is not a guarantee about where the true effect lies, and it does not correct for bias, differences in treatment regimens, or unreported analysis decisions. Here, the interval is based on a recalculation from the posted summary statistics rather than a sponsor-reported model. The registry does not report a sponsor analysis or its interval for this comparison.

Precision is also distinct from whether an estimate crosses a conventional threshold for statistical significance. The p-value is 0.431, but that single value does not show the range of plausible effects. The interval and the modest group sizes provide a clearer view of how uncertain the primary contrast remains. In particular, the result does not tightly distinguish a favorable contrast, no contrast, or a contrast in the other direction.

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, not the number of participants in the trial and not the number analyzed for the primary outcome. For the binary outcomes in this record, each figure is participants per arm, rather than a total across arms or a total number of events. The listed planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to be detected is set in turn to the stated fraction of the observed effect. The trial’s original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column represents the number of participants per arm that the planning calculation estimates would be needed to have an 80% chance of detecting the specified effect under the stated assumptions. The 90% power column uses a higher target chance of detecting that effect and therefore generally calls for a larger planned group. These are prospective planning quantities, not properties measured from the completed study. This is not observed power.

The rows for planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect show how the assumed target effect changes the planning requirement. Smaller effects need more participants to detect, all else equal. The displayed figures are illustrations using the observed contrast as a starting point; the observed contrast is uncertain, particularly given the small primary analysis groups and broad confidence interval. They should not be interpreted as evidence that the original investigators planned the study using these assumptions, or as evidence about the probability that the actual trial detected an effect.

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 = 0.300; treatment proportion p₁ = 0.462; average p̄ = 0.381.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6867 = 1.3459.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6771 = 0.5699.
4. n = (1.3459 + 0.5699)² / (0.1615)² = 140.7, rounded up to 141 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 <- 0.3                          # control proportion
p1 <- 0.461538461538462                          # 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(3600805)
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 = 141 (80% power), 188 (90% power)
 75% of observed effect: n per arm = 246 (80% power), 329 (90% power)
 50% of observed effect: n per arm = 540 (80% power), 722 (90% power)
power.prop.test: 140.7 
Simulated power at n = 141 per arm: 0.803 (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. Multiplicity, Missing Data and Analysis Populations

The registry record lists many outcome measures and secondary outcomes, but it does not report a prespecified multiplicity strategy, a testing hierarchy, or whether any adjustment was applied to secondary comparisons. This matters because examining multiple outcomes can produce apparently notable results by chance even when there is no underlying effect. The unadjusted recalculations should therefore be interpreted cautiously, particularly when considered alongside the full set of outcomes rather than one result in isolation.

Comparative analyses for the posted results are not reported in the registry record. The available p-values and effect comparisons are recalculations from posted summary statistics, not descriptions of a reported sponsor model. The registry record does not report the original statistical analysis plan, planned covariate adjustments, stratification factors, or the intended inferential procedures. It is therefore not possible to establish whether the recalculations reproduce the planned trial analysis.

Missing-data handling is also not reported in the registry record. The primary outcome requires information on remission, flares, CRP, and prednisone-taper adherence over time. Without the stated rules for missing visits or incomplete component data, the effect of missing observations on endpoint classification cannot be assessed. The record does not state whether missing values were imputed, treated as failures, or handled through another method; none of these approaches should be assumed.

The populations vary across outcomes. The primary endpoint uses the Week 52 analysis set, defined as randomized participants who had the opportunity to complete the 52-week treatment period, with the record specifying randomization before October 16th, 2019. Some secondary outcomes use this analysis set, while others use the intent-to-treat population. The registry does not report all analysis-population rules or explain how participants who stopped treatment or lacked follow-up were treated in each analysis.

These omissions do not invalidate the posted descriptive results, but they limit a full assessment of bias and statistical inference. They also make comparisons between outcomes harder to interpret. The analysis set, missing-data rules, and multiplicity approach would be important context for judging how robust any reported contrast is.

15. 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: neutropenia (7.4%), blindness unilateral (7.1%), retinal artery occlusion (7.1%), hiatus hernia (7.1%), pyelonephritis (7.1%).

The registry reports serious adverse events by treatment group, with the number at risk and the number affected. The placebo plus 52-week taper group had 2 serious adverse events among 28 at risk; the placebo plus 26-week taper group had 3 among 14; the sarilumab 150 mg plus 26-week taper group had 2 among 14; and the sarilumab 200 mg plus 26-week taper group had 7 among 27. The listed death counts were 0, 1, 0, and 2, in the same group order. These are descriptive counts, not adjusted comparisons.

The record also lists serious-event terms with percentages: Neutropenia, 7.4%; Blindness Unilateral, 7.1%; Retinal Artery Occlusion, 7.1%; Hiatus Hernia, 7.1%; Pyelonephritis, 7.1%; and Septic Shock, 7.1%. The registry record does not establish from these term listings which treatment group each term belongs to, or whether any event was judged related to study treatment. The figures should not be read as evidence of causation.

Safety groups have different numbers at risk, and the registry does not report a comparative safety analysis or the methods used to assess treatment attribution. The counts describe events recorded in the registry, not a reliable ranking of the regimens’ safety.

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

The primary result describes the proportion meeting a demanding, multi-component definition of sustained remission at Week 52 in two treatment groups. The observed percentages were 30.0% for placebo with a 52-week taper and 46.2% for sarilumab 200 mg every 2 weeks with a 26-week taper. The comparison is imprecise: the groups were small, the confidence interval includes no difference, and the unadjusted recalculated p-value is 0.431. These results do not establish a clear difference between the compared regimens.

The result does not isolate the effect of sarilumab from the effect of prednisone-taper duration. The primary comparison combines sarilumab with a 26-week taper and placebo with a 52-week taper. Any observed contrast could reflect the combined regimen differences, and the posted comparison cannot determine which component accounts for it. The other treatment arms offer descriptive context, but the registry does not report sponsor comparative analyses across all arms.

The registry’s terminated status does not explain why the study ended. A reason is not reported in the registry record, so the status alone cannot support a conclusion about efficacy, safety, recruitment, or any other cause. Similarly, the registry outcome summaries do not establish what would have been observed in a larger study, another population, or a study with a different taper design.

Statistical uncertainty is not the same as proof that there is no effect. An interval that crosses no difference indicates that the data remain compatible with a range of possibilities; it does not show that all possibilities are equally likely or that the regimens are equivalent. Equivalence or non-inferiority would require an appropriate design and prespecified margin, neither of which is reported in the registry record.

The findings should therefore be read as registry-reported outcomes from the analyzed groups, accompanied by substantial uncertainty and important design and analysis limitations. They do not by themselves establish treatment benefit, lack of benefit, or a causal explanation for the observed percentages.

17. Why This Trial Matters Statistically

This trial is statistically instructive because its primary outcome combines several clinically meaningful dimensions into one binary endpoint. Sustained remission requires an early remission response, continuing absence of flare, normalized CRP, and adherence to a prednisone taper. Such a composite can summarize a broader treatment goal, but its result depends on every component and can be difficult to interpret without component-level context. A participant can fail the composite despite meeting several of its parts.

The regimen comparison also highlights the importance of identifying exactly what is contrasted. The primary result compares sarilumab with a 26-week taper against placebo with a 52-week taper. It is not a drug-only contrast with a common taper schedule. This matters when assigning meaning to an observed difference: a regimen-level comparison cannot separate the effect of each regimen component.

The small analysis groups and wide interval illustrate why an observed percentage difference should be considered alongside precision. A point estimate can appear directional while the confidence interval remains compatible with no difference and effects on either side. This is particularly important for binary outcomes, where a small number of outcomes can shift the group proportion.

The registry also makes population definitions consequential. The primary analysis set is restricted to participants who had the opportunity to complete the treatment period, while some secondary outcomes are reported for an intent-to-treat population. Such distinctions affect the question answered by each result. Missing-data rules, the original analysis plan, and multiplicity methods are not reported, leaving important inferential context unavailable.

Together, these features demonstrate why registry results should be read as a combination of endpoint definition, population, treatment contrast, effect estimate, and uncertainty, rather than as a single percentage or p-value.

18. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several limitations specific to this study affect interpretation. First, the primary outcome analysis groups are small: 10 participants in the placebo plus 52-week taper group and 13 in the sarilumab 200 mg plus 26-week taper group. The resulting estimate is imprecise, as reflected by a confidence interval that crosses no difference and spans both directions.

Second, the primary comparison changes both assigned study drug and prednisone-taper duration. It therefore estimates a contrast between the two stated regimens rather than isolating sarilumab’s contribution. The other listed arms include placebo with a 26-week taper and sarilumab 150 mg with a 26-week taper, but comparative analyses for the registry results are not reported.

Third, the primary endpoint is a composite with several requirements over time. The overall sustained-remission percentage does not show which component most often prevented participants from meeting the definition. The record provides selected secondary outcomes related to remission and flare, but does not provide every component result in a comparative analysis.

Fourth, the record does not report missing-data methods, the original analysis plan, multiplicity procedures, sponsor-reported comparative analyses, or the reason for termination. The primary population is also restricted to participants with an opportunity to complete the 52-week treatment period, while some secondary results use an intent-to-treat population. These factors limit assessment of robustness and comparability across results.

Finally, the safety summaries are descriptive, and the registry does not report a comparative safety analysis or event-attribution methods. These limitations mean the posted figures should be treated as observations from the recorded populations, not as a complete assessment of the treatment regimens.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Evaluation of Efficacy and Safety of Sarilumab in Patients With GCA — NCT03600805.
• Registry record last updated 2022-03-28; status last verified 2022-03.
• Results first posted 2022-01-14.
• 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.

22. Record Summary

The registry record describes a randomized, quadruple-masked, parallel-group Phase 3 study of sarilumab in giant cell arteritis. It lists an enrollment of 83, a start date of 2018-11-20, primary completion on 2020-11-24, and a terminated status; the reason for termination is not reported in the registry record.

The primary outcome is sustained disease remission at Week 52 in the Week 52 analysis set. The central posted comparison is sarilumab 200 mg every 2 weeks with a 26-week taper versus placebo with a 52-week taper. The recorded percentages were 46.2% and 30.0%, respectively, based on groups of 13 and 10. The recalculated unadjusted comparison is imprecise and its confidence interval includes no difference.

The registry lists 22 outcome measures and 20 posted secondary outcomes. The record does not report sponsor comparative analyses, the original statistical analysis plan, missing-data procedures, multiplicity methods, or the original sample-size justification. Secondary and safety results should be interpreted descriptively in light of those limitations.