This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study to Evaluate the Safety and Efficacy of Satralizumab in Participants With Neuromyelitis Optica Spectrum Disorder (NMOSD) (NCT04660539), a na phase 3 study. The primary outcome is Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04660539 |
| Phase | Phase 3 |
| Condition | Neuromyelitis Optica Spectrum Disorder |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 119 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Hoffmann-La Roche |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns participants with neuromyelitis optica spectrum disorder (NMOSD) who had completed the open-label extension period of studies BN40898 and BN40900. The registry lists 119 participants enrolled in the current study. The primary safety outcome uses a broader all-participants-treated population: participants who received at least one dose of satralizumab during either a parent study or the current study, whether or not they enrolled in the current study. That population contains 166 participants.
Intervention
Participants received satralizumab subcutaneously every 4 weeks. Treatment could be satralizumab alone or satralizumab with azathioprine, mycophenolate mofetil, or oral corticosteroids, according to the study summary. The record does not report how many participants received each background treatment.
Comparator
There was no concurrent comparison group. The study is listed as single-group, with allocation recorded as NA and masking recorded as NONE. Consequently, the posted safety counts describe participants treated in this study program; they are not a randomized comparison with another treatment or with no treatment.
Primary question
The primary outcome counts participants with adverse events (AEs) and serious adverse events (SAEs), from baseline up to 523 weeks. The central question is descriptive: how many participants in the defined treated population were recorded as having these events? The registry also lists relapse, disability, suicidality, serious infection, and hepatotoxicity outcomes, but their results are not reported in the registry record.
3. Trial Design
This is a phase 3, multicenter, single-arm, open-label study of satralizumab in participants with NMOSD. The registry lists the study as completed. Its start date is 2021-03-02, and its primary completion date is 2024-05-28. The planned enrollment listed for the current study is 119. Those design details describe the current study, while the primary safety population extends to participants treated with satralizumab in the parent studies as well.
Participants were eligible after completing the open-label extension period of studies BN40898 and BN40900. The study summary describes satralizumab as either monotherapy or treatment combined with azathioprine, mycophenolate mofetil, or oral corticosteroids. The arm description specifies subcutaneous satralizumab every 4 weeks. The registry does not give the number receiving each treatment combination, nor does it report a randomized allocation between those treatment options.
Single-arm and open-label describe important features of how the evidence was collected. A single-arm study has no concurrent control arm for direct comparison, and open-label means masking is absent. The registry records allocation as NA and masking as NONE. These features do not invalidate descriptive safety counts, but they limit what can be attributed to satralizumab alone: events can be counted during treatment, while a contrast against what would have occurred under another condition is not available from this design.
The registry reports 18 outcome measures overall. Named secondary outcomes include suicidality assessed using the Columbia-Suicide Severity Rating Scale, serious infections and hepatotoxicity, investigator-assessed protocol-defined relapse, relapse-free status, annualized relapse rate, and disability measures based on the Expanded Disability Status Scale. Results for those outcomes are not reported in the registry record. The statistical analysis plan, including any planned interim analyses, is 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: Participants from NCT02028884 and NCT02073279 enrolled in this study to receive satralizumab treatment. Participants were permitted to use azathioprine (AZA) or mycophenolate mofetil (MMF) or oral corticosteroids during the study as background immunosuppressive treatments.
Overall Study
| Stage | Satralizumab |
|---|---|
| STARTED | 166 |
| COMPLETED | 106 |
| NOT COMPLETED | 60 |
Reasons for not completing this period:
| Reason | Satralizumab |
|---|---|
| Adverse Event | 10 |
| Lack of Efficacy | 4 |
| Lost to Follow-up | 5 |
| Non-Compliance With Study Drug | 3 |
| Reason not Specified | 12 |
| Pregnancy | 2 |
| Protocol Violation | 2 |
| Switch To Commercial Satralizumab | 1 |
| Withdrawal by Subject | 21 |
Analysis population for the primary outcome, as defined in the registry: All Participants-treated population included participants who received at least one dose of satralizumab at any time either during the parent studies or this study, irrespective of enrollment in current 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.
Population: All Participants-treated population included all participants who received at least one dose of satralizumab at any time either during the parent studies or this study.
| Characteristic | Unit | Satralizumab |
|---|---|---|
| Participants analysed | 166 | |
| Age, Continuous | years | 42.7 (SD 13.3) |
| Sex: Female, Male: Female | Participants | 142 |
| Sex: Female, Male: Male | Participants | 24 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 12 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 147 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 7 |
| Race/Ethnicity, Customized: American Indian or Alaska Native | Participants | 2 |
| Race/Ethnicity, Customized: Asian | Participants | 47 |
| Race/Ethnicity, Customized: Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race/Ethnicity, Customized: Black or African American | Participants | 17 |
| Race/Ethnicity, Customized: White | Participants | 95 |
| Race/Ethnicity, Customized: More than one race | Participants | 0 |
| Race/Ethnicity, Customized: Other | Participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs), measured over Baseline up to 523 weeks.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with adverse events and serious adverse events. An AE is defined in the registry as an untoward medical occurrence after administration of a pharmaceutical product, whether or not it is considered causally related. The definition includes an unfavorable or unintended sign, symptom, or disease temporally associated with use of the medicinal or investigational product. An SAE is an event that meets the record’s seriousness criteria, including being fatal or life-threatening, requiring hospitalization or prolonging hospitalization, causing persistent or significant disability or incapacity, involving a congenital anomaly or birth defect, or being medically significant or requiring intervention.
Counting participants is a straightforward way to describe how many people experienced an event under the endpoint definition. It is useful for safety reporting because it expresses event occurrence at the participant level rather than treating repeated events in the same person as separate affected participants. The posted primary results report affected-participant counts; they do not provide event counts per person, exposure-adjusted rates, or a comparison between treatment groups.
The timeframe is baseline up to 523 weeks. For this outcome, baseline is defined using the first dosing visit in the current study or the randomization visit in the parent studies, and all AEs from randomization in the parent studies for satralizumab-treated participants are included. This scope matters when interpreting the endpoint: it encompasses experience across the parent-study treatment history and the current study, rather than only events starting after enrollment in the current study.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary safety results describe a treated population of 166 participants. Within the satralizumab group, 44 participants are recorded as having an SAE, and 155 are recorded as having an AE other than the serious-event count shown. The death count is 0. These are participant counts, not estimates of a treatment contrast. The registry does not give a concurrent control group, so these counts cannot establish whether the events occurred more or less often than they would have under another treatment or without satralizumab.
The denominator for these safety results is not the current-study enrollment of 119. The primary outcome population includes participants who received at least one satralizumab dose during a parent study or the current study, regardless of enrollment in the current study, and its size is 166. This difference follows from the record’s population definition; it should not be read as an inconsistency in the count of current-study enrollment. The outcome also includes AEs from the time of randomization in the parent studies for satralizumab-treated participants.
The record lists pneumonia at 3.0%, influenza at 1.8%, urinary tract infection at 1.8%, uterine leiomyoma at 1.8%, cellulitis at 1.2%, and urosepsis at 1.2% among the top serious terms. These percentages are reported as serious-event terms. The registry excerpt does not specify a denominator or provide additional detail about how overlapping terms or repeated events were handled, so the percentages should be read as reported rather than converted into participant counts.
The primary outcome is safety-focused. Although the registry lists relapse and disability outcomes, their results are not reported in the registry record. It is therefore not possible from the posted results to characterize the observed relapse experience, disability changes, or the precision of those efficacy outcomes. Likewise, no confidence intervals or comparative estimates are reported for the primary safety counts.
In general, an estimate is more informative when its uncertainty is reported alongside it. A confidence interval conveys a range of values compatible with the data under the analysis assumptions; it does not by itself resolve confounding or create a control group. Here, the available primary results are counts without reported uncertainty intervals. The design and population definitions are therefore essential context: the results are descriptive observations accumulated across a broader treated population and follow-up history, not a controlled estimate of a causal effect.
The registry records no analyses. The statistical plan and any methods used to handle repeated events, missing observations, or differences in follow-up are not reported in the registry record. The absence of those details limits further statistical interpretation, but it does not change the plain meaning of the posted counts: they identify participants recorded with the defined safety outcomes in the specified treated population.
9. Statistical Methods Explained
Interpretation begins with the type of quantity reported. The primary result is a count of participants with an event, rather than a continuous measurement such as a score or a time-to-event estimate. Participant counts answer how many people in the defined population met the outcome definition. They do not, on their own, describe how many total event episodes occurred, how long each participant was observed, or how quickly events arose.
What does a participant count capture?
For a participant-level outcome, a person is counted as affected if the event definition is met. If an individual experiences multiple events that fall under the same outcome, the participant count does not necessarily increase for each additional episode. Event-level totals and participant-level totals answer different questions. The registry’s primary outcome is explicitly a number of participants, so its reported counts should be interpreted at that level.
The record defines an AE broadly: an untoward medical occurrence after a pharmaceutical product is administered, regardless of whether a causal relationship is judged to exist. The SAE definition uses seriousness criteria such as death or a life-threatening event, hospitalization or longer hospitalization, significant disability or incapacity, a congenital anomaly or birth defect, or medical significance requiring intervention. These definitions classify what is counted; they do not establish that the study drug caused an event.
Why does the analysis population matter?
The current-study enrollment is 119, while the primary safety population is 166. The latter includes anyone who received at least one dose of satralizumab during either the parent studies or the current study, irrespective of enrollment in the current study. The endpoint description further states that AEs from parent-study randomization are included for satralizumab-treated participants. A population definition determines who contributes to the reported count, so using the enrollment figure as the denominator for the safety count would not match the registry’s stated analysis population.
Follow-up duration also affects interpretation. The primary outcome timeframe is baseline up to 523 weeks, with baseline based on the first dosing visit in the current study or the randomization visit in the parent studies. The record does not report participant-specific follow-up durations or exposure-adjusted event rates. In general, when observation time varies, a simple count does not account for how long each person was observed. Exposure-adjusted rates can address time at risk, but no such rate is posted for this outcome.
What does the single-arm design permit?
In general, a concurrent comparison group helps distinguish changes associated with treatment from changes that could arise from the underlying condition, background care, or other factors. This study is single-group and open-label, with no control arm listed. Its safety results can describe events among treated participants, but they do not estimate a between-group difference. Nor can a single-arm count, by itself, separate treatment effects from other explanations for observed events.
Open-label status means masking is absent in the registry record. In general, knowledge of treatment assignment can affect reporting or assessment, especially for outcomes that involve judgment. That possibility is a general design consideration, not evidence that any particular event was misclassified in this study. The registry does not report procedures that would permit further evaluation of that issue.
How should uncertainty be understood?
In general, statistical uncertainty describes how much an estimate might vary because it is based on a finite set of observations. A confidence interval is one common way to express that uncertainty under specified assumptions. It does not show whether an estimate is free from bias, and it cannot compensate for a missing comparison group. The registry record does not report confidence intervals for the primary counts, so the precision of those counts cannot be assessed from the posted results beyond their stated values and population.
The record lists 0 analyses. It does not report the statistical analysis plan, an interim-analysis plan, or methods for accounting for differences in observation time. No p-values or adjusted comparative estimates are reported for the primary outcome. It would therefore be inappropriate to infer an unreported statistical model or to treat the raw counts as though they were results from an adjusted analysis.
What do the planning illustrations represent?
General sample-size calculations estimate how many participants might be needed to detect a specified effect under chosen assumptions. The registry’s planning assumptions describe an illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Those assumptions do not describe this trial’s single-group design. Any such calculations are planning illustrations, not observed power, and the trial’s own sample-size justification is not reported in the registry record.
For time-to-event planning, the record states that the illustrations use a total number of events, while other illustrations use participants per arm. These conventions describe the planning calculations, not observed outcomes. They do not supply evidence of a treatment effect, and they do not turn the single-arm study into a randomized comparison. No additional sample-size result or design rationale should be inferred from those assumptions alone.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 18 outcome measures overall, including several secondary outcomes related to relapse, disability, suicidality, serious infections, and hepatotoxicity. When a study examines multiple outcomes or multiple analyses, the chance of at least one apparently notable result can increase if each is interpreted without regard to the full set of tests. In general, multiplicity procedures can control that issue, but they must be specified and applied in the analysis. Whether such procedures were planned or used is not reported in the registry record.
The record does not report a statistical analysis plan, planned interim analyses, or results for the listed secondary outcomes. It also does not report how missing observations were handled, how incomplete follow-up was addressed, or whether sensitivity analyses were conducted. These omissions prevent assessment of whether missingness or analytic choices could influence particular endpoint estimates. They do not establish that data were missing or that an analysis was inadequate; the relevant methods are simply not reported in the registry record.
The primary safety population is explicitly defined as all participants who received at least one satralizumab dose during the parent studies or current study, whether or not they enrolled in the current study. That definition is important when reading the counts. The record does not describe further analysis populations, such as a population limited to current-study enrollees, and no such population should be assumed.
The registry records 0 analyses and provides participant counts for the primary safety outcome. No confidence intervals, p-values, adjusted comparisons, or missing-data analyses are reported. As a result, the posted primary figures support a descriptive account, but they do not permit a review of multiplicity control, statistical precision, or sensitivity to missing-data assumptions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Satralizumab | 44 | 166 | 26.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Satralizumab | 0 of 166 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Satralizumab | 155 of 166 |
Most frequent serious adverse event terms
| Event term | Organ system | Satralizumab |
|---|---|---|
| Pneumonia | Infections and infestations | 5 of 166 |
| Influenza | Infections and infestations | 3 of 166 |
| Urinary tract infection | Infections and infestations | 3 of 166 |
| Uterine leiomyoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 3 of 166 |
| Cellulitis | Infections and infestations | 2 of 166 |
| Urosepsis | Infections and infestations | 2 of 166 |
| Spinal compression fracture | Injury, poisoning and procedural complications | 2 of 166 |
| Mental status changes | Psychiatric disorders | 2 of 166 |
| Cervical dysplasia | Reproductive system and breast disorders | 2 of 166 |
| Anaemia macrocytic | Blood and lymphatic system disorders | 1 of 166 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Satralizumab |
|---|---|---|
| Nasopharyngitis | Infections and infestations | 48 of 166 |
| Upper respiratory tract infection | Infections and infestations | 46 of 166 |
| Headache | Nervous system disorders | 44 of 166 |
| Urinary tract infection | Infections and infestations | 40 of 166 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 35 of 166 |
| COVID-19 | Infections and infestations | 31 of 166 |
| Pain in extremity | Musculoskeletal and connective tissue disorders | 26 of 166 |
| Injection related reaction | Injury, poisoning and procedural complications | 24 of 166 |
| Diarrhoea | Gastrointestinal disorders | 21 of 166 |
| Nausea | Gastrointestinal disorders | 21 of 166 |
Serious events with the highest arm-level rate: pneumonia (3.0%), influenza (1.8%), urinary tract infection (1.8%), uterine leiomyoma (1.8%), cellulitis (1.2%).
The safety results list 166 participants in the satralizumab group at risk for the reported outcomes. The registry records 44 participants affected by serious adverse events and 155 affected by other adverse events; the reported death count is 0. These are participant counts over the outcome’s stated timeframe, not event rates per unit of exposure. The endpoint includes the parent-study experience for satralizumab-treated participants as well as the current study, so the counts do not apply only to the 119 participants enrolled in the current study.
The serious-event terms listed with percentages are pneumonia at 3.0%, influenza at 1.8%, urinary tract infection at 1.8%, uterine leiomyoma at 1.8%, cellulitis at 1.2%, and urosepsis at 1.2%. The percentages are reported by the registry; the denominator and handling of repeated or overlapping terms are not reported in the registry record. A term appearing on this list does not establish that satralizumab caused the event. The AE definition explicitly includes events regardless of causal relationship, and the study has no concurrent control group for comparative safety interpretation.
In general, safety counts are best read alongside the population definition, observation period, event definitions, and method for accounting for exposure. The record states the first three elements in part, but does not report exposure-adjusted rates or participant-specific follow-up. The figures therefore describe recorded experience in the stated treated population, without a direct estimate of excess or reduced risk compared with another group.
12. What the Result Does, and Does Not, Mean
The posted results support a descriptive statement about safety events recorded among satralizumab-treated participants across the parent studies and current study. The primary outcome reports 44 participants with SAEs and 155 with other AEs among 166 participants in the defined safety population, with 0 deaths recorded. The scope of that population and the extended timeframe are part of the result’s meaning: the count is not limited to current-study enrollment or to events observed only after current-study entry.
The results do not establish a causal relationship between satralizumab and any individual event. The registry’s AE definition explicitly includes events whether or not they are considered related to the product. A single-arm study also lacks a concurrent treatment group against which to compare the observed counts. This means the results do not quantify how event occurrence would differ under another treatment or under no satralizumab exposure.
The record names several efficacy-related outcomes, including protocol-defined relapse, relapse-free status, annualized relapse rate, and changes in disability scores. Their results are not reported in the registry record. The safety counts therefore cannot be used to conclude anything about those outcomes. The record also does not report confidence intervals or exposure-adjusted rates for the primary safety endpoint, limiting assessment of statistical precision and differences in follow-up.
In general, a study can be informative about the experience of its participants without answering every comparative or causal question. Here, the study provides a long-term treated-population safety description, while a controlled estimate of comparative safety is not available from the design. The appropriate reading is neither to treat the counts as proof of causation nor to treat the absence of a control group as proof that the observations have no descriptive value. The population definition, follow-up scope, event definitions, and unreported analytic details set the boundaries of what can be inferred.
13. Why This Trial Matters Statistically
This study is statistically notable for the way its primary safety population differs from its current-study enrollment. The registry lists 119 participants enrolled in the current study, but defines the primary safety population to include participants treated with satralizumab in the parent studies regardless of current-study enrollment. That population contains 166 participants. Recognizing this distinction is essential to interpreting the denominator and prevents a reader from assuming that the primary safety counts describe only current-study enrollees.
The outcome also spans treatment experience from parent-study randomization through a timeframe stated as baseline up to 523 weeks. Long follow-up can make a descriptive safety record useful for understanding events observed over time, but a raw count does not account for differences in individual observation time. The registry does not report exposure-adjusted rates or participant-specific follow-up, so those limitations should remain visible when interpreting the counts.
The single-arm, open-label structure illustrates a broader statistical distinction between describing events and estimating comparative effects. Participant counts can document what was recorded in the treated population, but the absence of a concurrent control group prevents a direct estimate of how those counts compare with another treatment condition. Open-label status also means masking is not part of the recorded design.
Finally, the record lists a broad set of safety and efficacy outcomes, while results are posted for the primary safety count only. The absence of reported analysis methods, precision estimates, and secondary outcome results limits evaluation of statistical uncertainty and the completeness of the evidence. These features make population definitions and transparent restraint in interpretation especially important.
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 study has no concurrent control group. Its single-arm, open-label design supports description of events among treated participants but does not provide a randomized or otherwise concurrent comparison for estimating relative safety or efficacy. Allocation is recorded as NA and masking as NONE. No causal contrast should be inferred from the primary counts alone.
The primary safety population includes participants treated with satralizumab in the parent studies or current study, whether or not they enrolled in the current study. The primary outcome also includes AEs from parent-study randomization for satralizumab-treated participants. This broader scope differs from the current-study enrollment of 119. The record does not provide a breakdown of the safety population by parent-study participation, current-study enrollment, background treatment, or duration of observation.
Although the timeframe is stated as baseline up to 523 weeks, participant-specific follow-up and exposure-adjusted rates are not reported in the registry record. The primary results are participant counts, with no reported confidence intervals or comparative estimates. The serious-event percentages are listed without a stated denominator in the record excerpt, and details about repeated or overlapping serious-event terms are not reported.
The registry does not report a statistical analysis plan, interim-analysis methods, missing-data methods, or multiplicity procedures. It lists 18 outcome measures, but results for the named secondary outcomes are not reported in the registry record. These gaps constrain interpretation of precision, completeness, and analysis choices. They do not establish that particular problems occurred; they identify information not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Evaluate the Safety and Efficacy of Satralizumab in Participants With Neuromyelitis Optica Spectrum Disorder (NMOSD) — NCT04660539.
- Registry record last updated 2024-12-27; status last verified 2024-11.
- Results first posted 2024-12-27.
- 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.
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18. Record Summary
NCT04660539 is a completed phase 3, multicenter, single-arm, open-label study evaluating long-term satralizumab safety and efficacy in participants with NMOSD who completed the open-label extension periods of studies BN40898 and BN40900. The registry lists 119 participants enrolled in the current study, with a start date of 2021-03-02 and a primary completion date of 2024-05-28.
Participants received subcutaneous satralizumab every 4 weeks, as monotherapy or with azathioprine, mycophenolate mofetil, or oral corticosteroids. The primary outcome counts participants with AEs and SAEs from baseline up to 523 weeks. Its all-participants-treated population contains 166 participants and includes satralizumab-treated participants from the parent studies regardless of current-study enrollment.
The posted primary safety counts are 44 participants with SAEs, 155 with other AEs, and 0 deaths. The study has no concurrent comparison group. Results for the listed secondary outcomes and the statistical analysis plan are not reported in the registry record.