Safety and Tolerability Study of Oral OPC-34712 as Maintenance Treatment in Adults With Schizophrenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Tolerability Study of Oral OPC-34712 as Maintenance Treatment in Adults With Schizophrenia (NCT01397786), a na phase 3 study. The primary outcome is Percentage of Participants With Adverse Events (AEs).

2. Clinical Question

3. Trial Design

This was a Phase 3, multicenter, open-label, single-group trial of oral OPC-34712 as maintenance treatment in adults with schizophrenia. The registry record identifies the allocation as NA and masking as NONE. These design features mean that the study was not a randomized, blinded comparison of OPC-34712 against a concurrent control. The record gives a planned enrollment of 1044 and lists the status as completed.

The recorded study period began in 2011-09, with primary completion in 2016-01. The primary endpoint covered baseline up to 52 Weeks. These dates describe the registry timeline; they do not establish the follow-up duration for each participant. Individual exposure and observation times are not reported in the registry record.

The adverse-event results are organized into De Novo (Phase A), Prior Brexpiprazole (Phase B), Prior Placebo (Phase B), and De Novo (Phase B). These labels describe the reported groups, but do not make them randomized comparison arms. In particular, group membership and prior-treatment history may distinguish the people represented in each set of counts. The record does not give enough detail to treat differences among these groups as treatment effects.

The study purpose includes long-term safety, tolerability, and efficacy, and the registry lists secondary outcomes involving PANSS, Clinical Global Impression, Personal and Social Performance, response, and discontinuation for lack of efficacy. The primary outcome reported for this analysis is the percentage of participants with AEs. The analysis results and statistical plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Enrollment was drawn from eligible participants who could potentially benefit from monotherapy treatment with oral brexpiprazole for schizophrenia and included rollover participants from the double-blind, phase-3 efficacy trials (ie, Trial NCT01393613, Trial NCT01396421, and Trial NCT01668797) and de novo participants from select sites.

Phase A

Reasons for not completing this period:

Phase B

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety sample included those participants who had at least one post-baseline efficacy evaluation for Positive and Negative Syndrome Scale (PANSS) total score.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Adverse Events (AEs), measured over From Baseline up to 52 Weeks.

The primary endpoint is the percentage of participants with adverse events (AEs), measured from baseline up to 52 Weeks. The record defines a treatment-emergent adverse event (TEAE) as an AE that started after investigational medicinal product (IMP) treatment began. An event already continuous from baseline is also counted if it was serious, related to IMP, or resulted in death, discontinuation, interruption, or reduction of IMP.

A participant-level percentage is a way to describe how often an event was recorded in the defined safety sample. It is useful in a safety study because it gives a direct summary of the proportion of participants who experienced an event during the specified observation period. It does not, by itself, describe the event's severity, duration, recurrence, or relationship to treatment. Those are separate questions requiring further detail.

The registry defines the safety sample as participants with at least one post-baseline efficacy evaluation for PANSS total score. That definition matters when interpreting the endpoint: the population used for the primary safety measure is not necessarily identical to the registry enrollment. The reported endpoint title identifies a percentage, but an overall primary-endpoint percentage is not included in the registry record. Therefore, the posted group counts should not be treated as a complete report of that endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For a binary safety endpoint, each participant is classified according to whether the event occurred during the endpoint's observation period. A percentage summarizes the fraction of the defined population with the event. In general, this is easy to interpret, but it depends on a clear denominator and consistent event ascertainment. The registry names the primary endpoint as a percentage of participants with AEs and states the period as baseline up to 52 Weeks. It does not report the overall percentage for that endpoint.

What does the event definition include?

The record uses a treatment-emergent definition. An event qualifies if it begins after IMP treatment starts. An event that was already continuous from baseline qualifies under the stated exceptions: if serious, related to IMP, or resulting in death, discontinuation, interruption, or reduction of IMP. This rule affects which observations enter the endpoint. It is not equivalent to counting every health event, regardless of its timing or characteristics.

In general, event classification requires decisions about onset, seriousness, and treatment relationship. Consistency in those decisions matters because misclassification can change the numerator. The registry gives the definition but does not report how events were assessed, adjudicated, or attributed in practice. Such procedures are not reported in the registry record.

How should the group counts be read?

The adverse-event entries present counts of participants at risk and affected, separately for serious events and the other reported category. The counts allow a reader to see the size of each recorded numerator and its corresponding at-risk count. They should be retained as group-specific entries, not pooled or treated as parallel randomized arms. The serious-event and other-event entries for De Novo (Phase B) have different at-risk counts: 224 and 256, respectively. The reason is not reported in the registry record.

In general, a count can be informative without being a comparative estimate. The groups have labels reflecting study phase or prior treatment, and the record does not establish that they were exchangeable at baseline. Differences in counts can reflect differences in group size, follow-up, participant characteristics, event ascertainment, or other factors. Because exposure time and comparable follow-up are not reported, a count should not be interpreted as an incidence rate or as evidence of a treatment difference.

What can statistical uncertainty add?

In general, a confidence interval communicates the range of values reasonably compatible with an estimate under a specified statistical model. It helps distinguish an imprecise estimate from one measured with greater precision. The registry record does not report a confidence interval or another uncertainty estimate for the primary endpoint or the adverse-event groups. No precision claim should be inferred from the counts alone.

For binary event data, statistical methods may also account for clustering, repeated events, follow-up time, or differences among participants, depending on the study question and data structure. The registry record does not report use of such methods. It also does not report a model, covariate adjustment, or inferential test for the safety results. The posted counts therefore support a descriptive reading, not a model-based conclusion.

What does the planning illustration represent?

In general, a sample-size calculation based on an observed effect is a planning illustration. It asks what sample size a future design might require under stated assumptions, such as a significance level, allocation pattern, and target fraction of an effect. It is not an observed result, and it is not observed power for the completed study. The stated assumptions for the illustrations are 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. For time-to-event illustrations, the stated quantity is total events; for other illustrations, it is participants per arm.

Those assumptions do not describe the recorded single-group trial design, which has no randomized comparator. The record does not report that these calculations formed part of the trial's original design or sample-size justification. The sample-size justification and the trial's own statistical plan are not reported in the registry record. The planning illustrations should be read as hypothetical design information rather than as evidence about the strength or success of the completed study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, including the primary AE endpoint and secondary measures of PANSS scores, Clinical Global Impression scores, Personal and Social Performance, response rate, and discontinuation for lack of efficacy. When a study evaluates multiple outcomes, general statistical practice may require a plan for how to interpret multiple tests or estimates. Such a plan can address the increased chance of finding an apparently notable result when many outcomes are examined. The registry record does not report a multiplicity adjustment or another strategy for handling multiple outcomes.

The record lists 0 analyses. It therefore does not provide inferential results for the primary endpoint or the listed secondary outcomes. Statistical analysis methods, prespecified analysis populations beyond the stated safety-sample definition, and any subgroup-analysis plan are not reported in the registry record. The absence of these details limits assessment of how the outcome results were selected, analyzed, and interpreted.

Missing-data procedures are also not reported in the registry record. The endpoint's stated observation period does not establish that every participant was observed for the same length of time, and the registry does not describe how incomplete follow-up or missing assessments were handled. The safety sample definition requires at least one post-baseline PANSS total-score evaluation, which is relevant to who is included, but it does not explain the treatment of missing AE information.

These omissions do not establish that an analysis or procedure was absent in practice; they mean that it cannot be evaluated from the registry record. No assumptions about interim analyses, imputation, censoring, or a statistical analysis plan are warranted.

11. Safety Results

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

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: schizophrenia (11.2%), psychotic disorder (1.8%), anxiety (0.9%), uterine cancer (0.5%), schizophrenia, paranoid type (0.5%).

The serious adverse-event entries report affected participants and participants at risk within each named group. The posted pairs are 4 and 226 for De Novo (Phase A), 90 and 605 for Prior Brexpiprazole (Phase B), 18 and 202 for Prior Placebo (Phase B), and 25 and 224 for De Novo (Phase B). These are counts, not rates adjusted for time at risk. No such adjustment can be made from the registry record.

The record separately reports other adverse-event counts: 0 among 226, 166 among 605, 53 among 202, and 95 among 256 for the same group order. It does not define the relationship between this category and the serious-event category in enough detail to infer that the categories are mutually exclusive. The differing at-risk counts for De Novo (Phase B) are reported as recorded and are not explained.

Listed serious terms include Schizophrenia, Psychotic disorder, Anxiety, Uterine cancer, Schizophrenia, Paranoid type, and Completed suicide, with percentages of 11.2%, 1.8%, 0.9%, 0.5%, 0.5%, and 0.5%, respectively. The registry does not report the denominator or selection method for these terms. A listed event does not by itself show that treatment caused it. Death counts are not reported in the registry record; a null entry should not be read as a count of zero.

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

The posted data describe adverse events recorded in a long-term, open-label, single-group study of OPC-34712. The primary endpoint was designed to summarize the percentage of participants with AEs during the period from baseline up to 52 Weeks, using a stated safety-sample definition. Group-level serious and other adverse-event counts are also reported, along with selected serious-event terms and percentages.

This is useful descriptive information about the safety experience recorded in the trial. It can help readers identify which events appear in the registry record and how the counts were organized across groups with different prior-treatment or phase labels. However, the primary endpoint's overall percentage is not reported, and the registry does not provide the analyses needed to quantify uncertainty around the posted counts.

The findings do not establish that OPC-34712 caused any listed event, nor do they establish that an event was unrelated to treatment. A single-group design has no concurrent randomized control with which to separate treatment-associated events from events that might occur for other reasons. The group labels do not create a controlled comparison. Differences in the posted counts should not be read as comparative treatment effects.

The record also does not establish that all participants had comparable follow-up, or report event timing, duration, recurrence, or detailed attribution. The stated endpoint window and event definition are important, but they do not supply those missing details. The available record therefore supports a bounded description of reported safety data, not a causal conclusion, a complete assessment of long-term risk, or a conclusion about efficacy.

13. Why This Trial Matters Statistically

This trial illustrates a common distinction in clinical research: describing events during treatment is not the same as estimating the treatment's effect on event risk. A safety-focused single-group study can document adverse events in the enrolled population, while a randomized concurrent comparison is generally needed to distinguish treatment effects from other influences. The registry identifies this study as open-label and single-group, so its safety counts should be interpreted accordingly.

The endpoint definition also matters. The TEAE rule specifies when an event is counted, including exceptions for events continuing from baseline. That makes clear that event totals depend not only on what occurred, but on how onset and qualifying circumstances are defined. The safety population definition matters as well: inclusion requires at least one post-baseline PANSS total-score evaluation. These details shape the population and events represented by the endpoint.

The registry's separate group counts and selected serious-event terms provide useful descriptive detail, but they do not substitute for a complete analysis. The primary endpoint's overall percentage, uncertainty estimates, statistical methods, and missing-data procedures are not reported in the registry record. These omissions show why interpretation requires attention to both the results and the information available about how those results were generated.

Finally, planning calculations based on an observed effect answer a different question from the trial's observed safety summary. They are hypothetical design illustrations under specified assumptions, not evidence of observed power or proof that the original study was adequately designed for a particular comparison. The distinction is especially important when the recorded study itself has no concurrent control group.

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 main design limitation for causal interpretation is the absence of a concurrent randomized control group. Allocation is listed as NA, masking as NONE, and the model as SINGLE GROUP. As a result, the registry's event counts describe what was recorded in the study groups but cannot isolate the effect of OPC-34712. The phase and prior-treatment labels do not remedy this limitation.

The registry does not report the overall result for the primary percentage endpoint, confidence intervals, hypothesis tests, or analysis methods. It also does not report a sample-size justification or the trial's statistical plan. Without those details, readers cannot assess the intended precision, inferential approach, or whether the posted summaries correspond to a prespecified analysis.

Follow-up and missingness are additional uncertainties. Although the endpoint timeframe is from baseline up to 52 Weeks, participant-level exposure and observation durations are not reported. The record does not describe how incomplete follow-up, missing AE assessments, or changes in treatment were handled. The at-risk counts differ between serious and other events for De Novo (Phase B), and the reason is not reported in the registry record.

Finally, the serious-event percentages are listed without a reported denominator or selection method, and death counts are not reported. The available detail does not show event timing, duration, recurrence, or attribution. These limits constrain interpretation of the safety profile and prevent the posted figures from serving as a complete comparative or causal evaluation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Tolerability Study of Oral OPC-34712 as Maintenance Treatment in Adults With Schizophrenia — NCT01397786.
• Registry record last updated 2017-05-10; status last verified 2017-04.
• Results first posted 2017-03-27.
• 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.

18. Record Summary

The registry record describes a completed Phase 3, multicenter, open-label, single-group trial of oral OPC-34712 as maintenance treatment in adults with schizophrenia. Registry enrollment was 1044. The recorded study period began in 2011-09, and primary completion was in 2016-01.

The primary outcome was the percentage of participants with AEs from baseline up to 52 Weeks. The TEAE definition includes events beginning after IMP treatment starts, with specified exceptions for events continuous from baseline. The safety sample required at least one post-baseline PANSS total-score evaluation.

Adverse-event counts are listed for De Novo (Phase A), Prior Brexpiprazole (Phase B), Prior Placebo (Phase B), and De Novo (Phase B). The registry also lists selected serious-event terms and percentages. The primary endpoint's overall percentage, statistical analyses, uncertainty estimates, and missing-data methods are not reported in the registry record. The design supports descriptive reading of the posted safety information, not a randomized comparison or causal conclusion.