Ocrelizumab for Preventing Clinical Multiple Sclerosis in Individuals With Radiologically Isolated Disease.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ocrelizumab for Preventing Clinical Multiple Sclerosis in Individuals With Radiologically Isolated Disease. (NCT04877457), a randomized phase 4 study. The primary outcome is Time to Development of First New Radiologic or Clinical Evidence of MS.

2. Clinical Question

RIS refers to radiological findings that meet the study's stated criteria in people being considered for the trial. The clinical question is therefore about time until a specified radiological or clinical event, rather than a change in a symptom score or a single scan finding alone. The registry identifies both lesion changes and a clinical demyelinating event as possible components of the endpoint.

The trial description says eligible participants were randomized in a 1:1 ratio to ocrelizumab or placebo. The registry records enrollment of 3, but it also states that primary efficacy data were not collected because of early termination. As a result, the clinical question is identifiable from the design and endpoint definition, but the posted record does not provide an efficacy comparison that answers it.

3. Trial Design

This was a Phase 4, multicenter, randomized, placebo-controlled study with a parallel-group design. The study description calls it double-blind, while the registry's masking entry is quadruple. The record does not explain how those masking descriptions relate to one another or identify the specific roles included in the masking designation.

Participants were to be assigned to ocrelizumab or placebo in a 1:1 ratio. The arm descriptions state that three courses of the assigned treatment were planned over the study. Placebo is described in the brief summary as standard of care. Further details about treatment administration, adherence, permitted additional care, and treatment discontinuation are not reported in the registry record.

The primary endpoint was time from baseline to the first new radiological or clinical evidence of MS. The registry gives its timeframe as “Up 4 years.” It defines radiological evidence as new T1 gadolinium-enhancing lesions and/or new or enlarging T2 lesions consistent with MS, and clinical evidence as a neurological event resulting from central nervous system demyelination with an acute or progressive syndrome consistent with MS.

The registry lists Yale University as the sponsor. It records a start date of 2022-02-15 and a primary completion date of 2023-06-12, and gives the study status as terminated. Enrollment is recorded as 3. The primary outcome entry explicitly states that data were not collected due to early termination. Consequently, the planned randomized comparison is described, but the posted record does not provide the primary outcome observations needed to assess the treatment contrast.

Several secondary outcomes are listed, including measures of T2 and T1 lesions, brain and spinal cord volume, and serum neurofilament light. The record does not report numerical results for these outcomes. It also does not explain the reason for termination or provide enough information to determine how much follow-up took place in either arm.

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: Data not collected due to early termination of study

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 Time to Development of First New Radiologic or Clinical Evidence of MS, measured over Up 4 years.

The primary endpoint is time from baseline to the first new radiological or clinical evidence of MS. The registry defines radiological evidence through new T1 gadolinium-enhancing lesions and/or new or enlarging T2 lesions consistent with MS. It also includes a clinical event: a neurological event resulting from central nervous system demyelination, evidenced by an acute or progressive syndrome consistent with MS. The recorded timeframe is “Up 4 years.”

Time-to-event endpoints are generally used when the timing of an event matters, not only whether it occurs. In general, such an endpoint can retain information about when participants experience the event during follow-up. A comparison may therefore concern the pattern of event timing between study arms, rather than simply comparing counts at a single visit. The statistical interpretation depends on complete definitions of the event, follow-up, censoring, and analysis methods.

Combining radiological and clinical evidence makes the endpoint a composite: any qualifying component can mark the first event. In general, a composite can capture different manifestations of a condition, but its interpretation depends on the components and their ascertainment. Here, the registry describes the components, but does not report component-level primary outcome results or an estimate of time to event.

Most importantly, the primary outcome record says that data were not collected due to early termination. No treatment-effect estimate, uncertainty interval, or primary endpoint comparison is reported in the registry record. Thus, the endpoint is defined, but the posted record cannot show whether or when the event occurred in either arm.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, parallel-group study with ocrelizumab and placebo arms. Randomization is generally used to make treatment assignment independent of participants' baseline characteristics, on average, so that a between-arm comparison can support causal interpretation when the study is conducted and analyzed appropriately. Randomization does not guarantee that the groups will be balanced, especially when enrollment is limited. In this record, primary efficacy data were not collected, so the planned randomized comparison cannot be evaluated from posted primary results.

What does masking mean?

Masking is intended, in general, to limit the influence of knowing treatment assignment on care, outcome assessment, or reporting. The study description calls the trial double-blind, and the registry masking entry says quadruple. The record does not define which people were masked or reconcile those labels. It would therefore be speculative to describe the specific masking procedures or assume that every person involved in the study was unaware of assignment.

Why use a time-to-event endpoint?

In general, time-to-event methods use both whether an event occurs and when it occurs during follow-up. They can also account for participants whose event has not been observed by the end of their available follow-up, provided the analysis handles censoring appropriately. The primary endpoint is time from baseline to the first qualifying radiological or clinical evidence of MS. The registry does not report a time-to-event estimate, the number or timing of events, censoring information, or the analysis method. No particular model or test can therefore be attributed to this study from the registry record.

The endpoint is composite because it includes radiological and clinical criteria. In general, an analysis of a composite endpoint treats a qualifying event in any included component as an endpoint event. Interpretation then depends on the definition and consistency of each component and on how events are assessed. The record provides the component definitions but no component-specific findings or details of event adjudication.

What do uncertainty measures tell readers?

Generally, a point estimate describes the observed treatment contrast, while a confidence interval communicates the uncertainty around that estimate under the analysis assumptions. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under a statistical model; it is not a measure of treatment importance or the probability that the null hypothesis is true. The registry reports no primary estimate, confidence interval, or p-value. Therefore, neither the size of a possible effect nor its statistical precision can be assessed.

Small or incomplete datasets can produce imprecise estimates, and estimates may be highly sensitive to individual observations. That is a general statistical concern, not a claim about an unreported analysis in this trial. Since the primary outcome data were not collected, there is no posted primary estimate to characterize as precise, imprecise, favorable, or unfavorable.

How should secondary outcomes be read?

The registry lists outcomes related to lesion counts and volumes, brain and spinal cord volume, and serum neurofilament light. These measures may describe different radiological or biological aspects of the condition. In general, secondary outcomes can help characterize a study beyond its primary endpoint, but their interpretation depends on their definitions, timing, analyses, and multiplicity handling. The registry does not report numerical results for these outcomes, nor does it report an analysis plan that would show how they were to be interpreted alongside the primary endpoint.

The record gives the number of outcome measures as 7 and the number of analyses as 0. Those entries do not reveal which statistical models were planned, whether outcomes were analyzed outside the registry, or whether any exploratory work occurred. Such details are not reported in the registry record.

What can sample-size calculations establish?

In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability or event frequency, significance level, allocation, and analysis. It is not an observed result and is not a substitute for a treatment-effect estimate. The registry record does not report a sample-size justification or the assumptions used to plan enrollment. Any illustrative calculation based on an observed effect would also require an observed effect estimate; the primary outcome entry says those data were not collected. No sample-size illustration should be interpreted as observed power or evidence that the trial detected a treatment effect.

Overall, the registry supports a description of the intended design and endpoint, and it documents the absence of collected primary efficacy data. It does not support reconstruction of a statistical analysis or a numerical efficacy conclusion.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary time-to-event endpoint and several secondary outcomes involving lesion measures, brain and spinal cord volume, and serum neurofilament light. When a study evaluates multiple outcomes or makes multiple comparisons, multiplicity can arise: in general, the chance of obtaining at least one apparently notable result may increase as the number of statistical tests grows. Methods such as a prespecified testing hierarchy or adjustment can address that concern, but the appropriate approach depends on the study's analysis plan.

Multiplicity handling is not reported in the registry record. The record gives the number of outcome measures as 7 and the number of analyses as 0, but those entries do not specify which outcomes would be tested together, whether any adjustment was planned, or how secondary results would be interpreted. Because no efficacy analyses are posted, there are no reported outcome tests from which to assess multiplicity in practice.

The primary outcome entry states that data were not collected due to early termination. A detailed missing-data policy, reasons for missingness, follow-up completeness, and the approach to participants without observed events are not reported in the registry record. These details matter generally because missingness can affect estimates, especially when the chance of having an observed outcome is related to participant characteristics or events. No missing-data mechanism or method should be assumed for this trial.

The registry record does not identify the analysis population, such as whether analyses were intended to follow randomized assignment or to include only participants meeting specified treatment or follow-up criteria. It also does not report exclusions or a participant flow description. Without those details and without primary outcome data, the analysis population and its relationship to the planned randomized comparison cannot be determined.

11. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports serious adverse events separately from other adverse events. For ocrelizumab, the serious-event figures are 0 affected among 2 at risk; for placebo, they are 0 affected among 1 at risk. The record also lists one other adverse event among 2 at risk in the ocrelizumab arm and one among 1 at risk in the placebo arm. No deaths are recorded in either arm.

These are counts from the registry record, not a complete assessment of comparative safety. The duration and completeness of safety follow-up are not reported, and the record does not describe event definitions, severity criteria for the “other” category, or how events were collected. The groups are small as recorded, and the counts alone cannot establish whether the treatments differ in risk. The absence of a recorded serious event is not proof that a treatment is free of serious harms; it means that none is listed in these registry figures.

The serious-event terms list is empty. That should be read as no serious-event terms listed in the record, rather than as evidence that all possible safety outcomes were assessed and ruled out.

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

The record establishes that a randomized, placebo-controlled Phase 4 study was planned to examine whether ocrelizumab could delay new radiological or clinical evidence of MS in people with radiologically isolated syndrome. It identifies the intervention, comparator, population criteria, masking descriptions, parallel-group design, and endpoint definition. It also records that the study was terminated and that primary efficacy data were not collected.

It does not establish whether ocrelizumab delayed the endpoint, whether the treatment arms differed, or how large or precise any effect might have been. There is no posted primary endpoint estimate, confidence interval, or statistical test. A study design can describe how a question was intended to be answered; it cannot itself provide the answer when outcome data are absent.

The reported adverse-event counts are limited registry entries. They show no serious adverse events recorded in either arm and one other adverse event recorded in each arm's at-risk group. They do not provide enough information to compare safety, characterize the nature or duration of events, or infer that a treatment has no risk.

The registry does not explain why the trial ended, how much follow-up occurred, or whether any analyses were conducted outside the record. Those unknowns cannot be resolved by interpreting the endpoint definition or the arm descriptions. The named secondary outcomes likewise indicate areas the study intended to measure, not findings, because numerical results are not reported.

The sound conclusion is narrow: the record documents a planned randomized comparison, but it does not contain the primary efficacy data required to answer the clinical question. Neither a positive nor a negative treatment conclusion can be drawn from the posted results.

13. Why This Trial Matters Statistically

This trial is statistically notable because its registry record distinguishes a clearly described planned question from the results needed to answer it. The design specifies random assignment to ocrelizumab or placebo, and the primary endpoint combines time to specified radiological findings with time to a clinical demyelinating event. Yet the record states that primary outcome data were not collected because the study ended early. This makes the boundary between design information and outcome evidence especially important.

For clinical researchers, the record illustrates why a registered endpoint and a completed analysis are not interchangeable. A precise endpoint definition can help readers understand what the trial intended to measure, but it cannot replace event observations, an effect estimate, or an account of uncertainty. Without those results, neither the size nor direction of a primary treatment contrast can be assessed.

The record also highlights the need to interpret small enrollment and limited safety counts cautiously. The posted arm-level adverse-event entries are descriptive, but they cannot carry the same weight as a complete safety analysis with documented follow-up and event ascertainment. Likewise, a list of secondary outcomes should not be read as a set of findings.

Finally, the record leaves important analysis questions unanswered, including how multiplicity, missing outcomes, and analysis populations were to be handled. These are standard considerations in clinical-trial interpretation, but no protocol or statistical plan is available in the registry record to resolve them. The main statistical lesson is therefore one of restraint: report what the design says, identify what the registry records, and do not infer efficacy where the primary data are absent.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most consequential limitation is stated directly in the registry: primary efficacy data were not collected due to early termination. The record provides no primary endpoint events, time-to-event estimate, uncertainty interval, or treatment comparison. It also does not explain the reason for termination, so the circumstances should not be inferred.

Enrollment is recorded as 3, and the record does not provide a participant flow account or explain how many people in each arm contributed follow-up to the primary endpoint. The adverse-event entries provide arm-level at-risk figures, but the duration and completeness of safety observation are not described. These limitations restrict interpretation of both efficacy and safety.

The registry does not report the statistical analysis plan, sample-size justification, analysis population, missing-data methods, multiplicity strategy, or specific time-to-event methods. It also does not report component-level primary endpoint results, secondary outcome results, or details of outcome assessment and event adjudication. Although the study description calls the design double-blind and the masking entry says quadruple, the record does not explain that distinction.

These omissions mean that the design can be described, but the intended inferential procedures and the reasons for the absence of results cannot be reconstructed. The record does not support a treatment-effect conclusion.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Ocrelizumab for Preventing Clinical Multiple Sclerosis in Individuals With Radiologically Isolated Disease. — NCT04877457.
• Registry record last updated 2024-10-09; status last verified 2024-10.
• Results first posted 2024-10-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes a Phase 4, multicenter, randomized, parallel-group, placebo-controlled study of ocrelizumab in people with radiologically isolated syndrome. Participants were to receive ocrelizumab or placebo, with three courses planned in each arm. The primary endpoint was time to first new radiological or clinical evidence of MS, with a timeframe recorded as “Up 4 years.”

The registry records enrollment of 3, a start date of 2022-02-15, a primary completion date of 2023-06-12, and a status of terminated. It states that primary efficacy data were not collected due to early termination. No primary efficacy estimate or secondary outcome results are reported. The adverse-event entries list no serious events in either arm and one other adverse event in each arm's at-risk group. The reason for termination and the statistical analysis plan are not reported in the registry record.