A Pharmacokinetic Study of MP-214 in Patients With Schizophrenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Pharmacokinetic Study of MP-214 in Patients With Schizophrenia (NCT01626859), a randomized phase 2, phase 3 study. The primary outcome is Number of Participants With Adverse Events as a Measure of Safety and Tolerability.

2. Clinical Question

The central question is descriptive as well as comparative. The event counts show how many participants in each group were recorded as having an adverse event. The comparison estimates address whether the observed proportion with an event differed between the 3mg group and either higher-dose group. They do not address differences in pharmacokinetics or efficacy: although those topics appear in the study objective, corresponding primary results are not reported in the registry record.

The record identifies a 12 Weeks Treatment Study in its official title, while the primary outcome timeframe is listed as up to 24 weeks. These descriptions should be kept distinct. The registry record does not explain how the treatment period relates to the outcome observation period, or when adverse events began or ended. The outcome therefore describes participants recorded with events within the stated timeframe, not the timing, duration, or severity of every event.

3. Trial Design

This was a randomized, parallel-group study with no masking listed in the registry record. The three groups received MP-214 3mg, MP-214 6mg, or MP-214 9mg. The record lists 38 participants enrolled and identifies schizophrenia as the condition. The study is classified as Phase 2 and Phase 3. Tanabe Pharma Corporation is listed as the sponsor.

The registry record lists the study start as 2012-05 and primary completion as 2013-08, and its status is completed. The official title describes a 12 Weeks Treatment Study. These registry entries describe the design and record status; they do not establish that every listed outcome was analyzed or posted. The arm descriptions contain no further details, so such matters as dose administration schedules, dose changes, adherence, and concomitant care are not reported in the registry record.

The 3mg group is designated as the control in the posted pairwise comparisons. This is an active-dose comparator, not an untreated or placebo group. Accordingly, the estimates compare the reported outcomes for the higher doses with those for 3mg. They do not estimate the effect of MP-214 relative to receiving no MP-214.

The registry record lists four outcome measures and no posted analyses. It gives a primary safety outcome and adverse-event information, but does not provide a detailed statistical analysis plan, a description of randomization procedures, the allocation ratio, or the populations included in each analysis. Those design and analysis details are not reported in the registry record. Randomization is recorded, but its method and implementation cannot be assessed from the listed information.

The study objective covers pharmacokinetics, safety, and efficacy, while the primary outcome described in the results is the number of participants with adverse events. The existence of an objective does not mean results for every objective are available in the registry record. In particular, pharmacokinetic and efficacy findings, and any separate endpoint-level results for the other listed outcome measures, 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.

Overall Study

Reasons for not completing this period:

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 Number of Participants With Adverse Events as a Measure of Safety and Tolerability, measured over Up to 24 weeks.

The primary outcome is the number of participants with adverse events, described in the registry record as a measure of safety and tolerability. The listed timeframe is up to 24 weeks. The posted values are participant counts: 11 of 11 in the 3mg group, 15 of 16 in the 6mg group, and 11 of 11 in the 9mg group. These are counts of participants recorded with at least one adverse event, not counts of all individual events. The record does not give event-level totals, onset dates, duration, severity grading, or a breakdown of non-serious events by type.

General: Counting participants with at least one event is a straightforward way to describe how many people in each group experienced an event during the observation period. It avoids treating multiple events in one person as if they came from separate participants. However, a participant count alone does not convey how often events occurred, how serious they were, or how long they lasted. Those questions require additional event-level information.

The outcome is relevant to the study’s stated safety and tolerability objective, but the count by itself cannot establish why an event occurred or whether an event was caused by the study drug. The registry record does not report an attribution method or a fuller endpoint definition. Its primary outcome should therefore be read as the reported number of participants with events, rather than as a complete account of the types, severity, or causes of adverse events.

7. Results Posted in the Registry

• MP-214 6mg: 93.8% (15/16) versus 100.0% (11/11) on control; risk difference -6.2 percentage points (95% CI -18.1 to 5.6), risk ratio 0.94 (0.83–1.06); unadjusted two-proportion z-test p = 0.398.
• MP-214 9mg: 100.0% (11/11) versus 100.0% (11/11) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0), risk ratio 1.00 (1.00–1.00); unadjusted two-proportion z-test p = n/a.

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count describe?

The primary outcome is a count of participants with adverse events. In the posted results, each group has a participant denominator and a count of participants with an event. This kind of outcome records whether a participant had an event during the defined timeframe, rather than how many separate episodes occurred. A person with multiple events may still contribute only once to a count of participants with at least one event. The registry record does not clarify the event-level counting rules beyond naming the outcome as a number of participants.

General: A binary outcome has two possible states for each participant, such as event recorded or no event recorded. Group results can be expressed as counts and as proportions. A comparison of proportions asks whether the share of participants with the event differs between groups. The posted comparison is expressed as a risk difference, which represents the difference between the two group proportions. A value of zero corresponds to no observed difference in those proportions; a negative or positive value indicates direction according to the comparison ordering used. These concepts describe the statistical measure, not a causal conclusion.

How should the risk difference be read?

The 6mg group is compared with the 3mg group. Its posted risk difference is negative, and the confidence interval crosses zero. The reported p-value is 0.398. In general, a confidence interval gives a range of values that are reasonably compatible with the data under the method used, while its width reflects precision. When an interval for a difference includes zero, the data do not clearly distinguish a difference from no difference at the confidence level used. This does not mean there is a stated probability that the true value is within the interval, and it does not prove that the groups are equal.

The registry record does not state the confidence level or the interval calculation method in the posted analysis description. It also does not report a p-value for 9mg versus 3mg. The 9mg comparison has equal observed participant counts and a reported risk difference and interval of zero. These reported results should be presented as recorded, not supplemented with an assumed test or method.

What does the p-value add?

General: A p-value measures how compatible the observed data, or results more extreme under a specified test, are with a null hypothesis under that test’s assumptions. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of a difference. The p-value of 0.398 accompanies the 6mg versus 3mg comparison. The registry record does not identify the test, whether the p-value was adjusted for multiple comparisons, or whether the analysis was specified before looking at the data. The number should therefore be read as a reported result without assuming unreported procedural details.

Why do small group counts matter?

General: With small samples, each participant’s outcome can have a noticeable influence on a group proportion. Estimates may be imprecise, and methods based on large-sample approximations may not behave as expected. Statistical methods for binary outcomes can differ in their treatment of small counts and groups in which everyone has an event. The registry record does not report enough methodological detail to determine which approach was used for the posted comparison, or whether alternative methods were examined.

The 3mg and 9mg groups each have all participants counted with an event. This complete observed event pattern affects what can be learned from a comparison of proportions, especially when group sizes are small. It does not mean the population event probability is known with certainty. Inferences beyond the participants observed remain uncertain, even when the observed count within a group has no variation.

What is over-dispersion, and is it relevant?

General: Over-dispersion describes more variability in data than a statistical model assumes. It can matter for count outcomes when the model treats events as arising from a specified distribution, because underestimated variability can make intervals too narrow or tests too optimistic. The primary outcome counts participants with an event, rather than reporting a modeled total number of recurrent events. The registry record does not report a model for recurrent event counts, a dispersion estimate, or an over-dispersion adjustment. There is therefore no basis to claim that over-dispersion was assessed or that it affected the posted result.

What do planning illustrations mean?

General: Sample-size planning uses assumptions about the effect to detect, significance level, allocation, and statistical method to estimate how many participants might be needed for a future design. An illustration based on an observed effect is a planning exercise, not evidence that the completed study had a particular probability of detecting an effect. The registry record does not report the original sample-size justification or design assumptions. Any planning illustration based on the observed effect should not be mistaken for observed power, a prespecified target, or proof that the trial was adequately sized.

The record describes an illustration using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of the observed effect. These are assumptions for the illustration, not confirmed features of the completed trial’s design or analysis. The record does not state the trial’s original rationale for its enrollment or whether these assumptions informed planning.

Randomization is listed, but the sequence-generation method and concealment procedures are not reported in the registry record. Masking is listed as none. The record also does not report the analysis population, handling of missing outcomes, covariate adjustment, model specification, or a complete statistical analysis plan. These omissions make it difficult to reproduce or fully evaluate the inferential comparisons.

10. Confidence Intervals and Precision

Precision concerns how narrowly the data locate an estimate. The 6mg versus 3mg comparison has a confidence interval extending below and above zero. Because zero lies within that interval, the result is compatible with no difference as well as with differences in either direction under the interval method. The reported p-value is 0.398. The interval’s width and the small group counts indicate that the comparison does not pin down a precise difference. Its exact lower and upper values are not needed to understand that it crosses zero.

The 9mg and 3mg groups have equal observed counts, and the posted risk difference and interval are all zero. That describes the observed comparison and its reported interval; it does not provide a guarantee that the underlying group probabilities are equal. A confidence interval is a property of an estimation procedure and data, not a measure of the range of individual participant outcomes. With small groups, a simple observed equality can coexist with uncertainty about results in a broader population.

General: A confidence interval is constructed by a statistical procedure that, under its assumptions, would cover the parameter at a stated rate over repeated applications. The registry record does not state the confidence level or the method used for these intervals. Consequently, interpretation should focus on the posted values and their relation to zero, without assigning an unstated coverage level.

The three group sizes are 11, 16, and 11. Such modest counts limit the detail that can be learned from the participant-level outcome, especially for rare or serious events. The primary outcome counts are near the upper bound of each group’s possible count, and serious events are reported in only one group. These patterns make it important to distinguish the observed records from precise estimates of event frequency in a larger population.

Planning illustrations are not a substitute for precision in the completed study. They use assumptions for hypothetical future sample sizes, and they do not alter the uncertainty in the actual comparisons. The registry record does not report a precision target, a margin for equivalence, or a non-inferiority margin. The equal counts in the 3mg and 9mg groups therefore cannot be interpreted as meeting an equivalence criterion.

11. Multiplicity, Missing Data and Analysis Populations

The study objective covers pharmacokinetics, safety, and efficacy, and the record lists four outcome measures. The posted analysis count is zero, while the results include participant counts for the primary safety outcome and adverse-event information. No secondary outcomes are posted in the record. Results for the remaining listed outcome measures, including results addressing pharmacokinetics and efficacy, are not reported in the registry record.

The primary outcome is compared across the 3mg, 6mg, and 9mg groups, with the two higher doses contrasted against 3mg. Multiple outcomes, groups, or comparisons can raise multiplicity concerns: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. General: Multiplicity procedures adjust interpretation or testing to account for a defined family of comparisons. The registry record does not report whether comparisons were grouped into a testing family, whether any adjustment was used, or whether a hierarchy of primary and secondary tests was prespecified. The p-value of 0.398 should therefore be treated as the posted value, not assumed to be adjusted or unadjusted unless the record specifies that status.

The 9mg comparison has no p-value listed. A missing p-value is not evidence that a test was performed and found no difference. Nor should one be reconstructed from the other posted comparison. The record does not report whether the comparison was planned, whether it was considered descriptive, or why no p-value appears.

Missing data handling and analysis populations are also not described. The posted outcome counts have denominators of 11, 16, and 11, but the registry record does not identify whether these are all randomized participants, treated participants, participants with observed outcome data, or another analysis population. It does not state whether any participant withdrew, how missing outcomes were handled, or whether imputation or sensitivity analyses were used. No assumptions about those procedures can be made from the group counts alone.

The unmasked design and absence of a reported statistical analysis plan further limit assessment of outcome ascertainment and analysis choices. These are limitations of the available record, not proof that an adjustment or missing-data procedure was absent from the conduct of the trial. Such details are simply not reported in the registry record.

12. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: schizophrenia (12.5%).

Serious adverse events are listed separately from the primary count of participants with any adverse event. The registry record reports 0 of 11 participants in the 3mg group, 2 of 16 in the 6mg group, and 0 of 11 in the 9mg group as having serious adverse events. The listed top serious adverse event term is Schizophrenia, at 12.5%. This term is an event category in the registry listing; its presence does not establish that the study drug caused a worsening of schizophrenia.

These counts are sparse. The two reported serious events are in the 6mg group, while none are listed in the other groups. That pattern alone does not show a reliable difference between doses. No statistical comparison for serious adverse events is reported in the registry record, and no causal attribution is described. Seriousness also does not necessarily convey the event’s relationship to treatment.

The death entries are not numeric results in the registry record. They should not be read as confirming that there were no deaths. The serious-event listing also does not supply a complete narrative, timing, duration, severity detail, or participant-level history. The safety information is therefore best read as a set of reported counts and a listed term, rather than as a full assessment of the type, cause, or comparative risk of serious events.

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

The result establishes what the registry record reports for the primary safety outcome: 11 of 11 participants in the 3mg group, 15 of 16 in the 6mg group, and 11 of 11 in the 9mg group had an adverse event. It also reports a comparison of 6mg with 3mg whose confidence interval crosses zero and whose p-value is 0.398. For 9mg versus 3mg, the reported difference and interval are zero, with equal observed counts. These statements describe the posted data and their statistical presentation.

They do not establish that one dose is safer than another, that the doses are equivalent, or that MP-214 caused or prevented the recorded events. The comparator is another MP-214 dose rather than placebo or no treatment. The registry record does not report an event-attribution method, and the outcome counts do not distinguish mild from severe events or show how many events each participant experienced.

The posted findings also do not answer the full study objective. Pharmacokinetic and efficacy results are not reported in the registry record. The record gives no basis for inferring an efficacy benefit or lack of benefit. Nor can the findings be generalized automatically to people beyond the study population: the enrollment is limited, group counts are small, and additional eligibility and participant characteristics are not reported in the registry record.

Uncertainty matters even when the observed counts are easy to describe. The interval for the 6mg comparison spans zero, and the equal counts for 9mg and 3mg do not amount to a formal demonstration of equivalence. Serious adverse event counts are also sparse. The record does not give the analysis populations, missing-data methods, or full statistical plan needed to evaluate all aspects of the comparisons.

The appropriate scope is therefore narrow: these are the reported participant counts and dose comparisons for the specified outcome and timeframe. They should not be expanded into conclusions about causation, clinical importance, effectiveness, or safety beyond what the record documents.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a simple participant-level safety outcome can be easy to summarize but difficult to interpret comparatively. The counts are direct: almost all participants in each group are recorded with an adverse event, and all participants in two groups are counted as having one. Yet these data alone do not tell how many separate events occurred, whether events differed in severity, or whether they were related to treatment.

The design also illustrates the distinction between an active-dose comparison and a comparison with no treatment. The registry record designates 3mg as the control, so the estimates address higher doses relative to that dose. They cannot estimate the difference between MP-214 and placebo or usual care. The interpretation should follow the actual comparison rather than treating the control label as if it meant an untreated group.

Small group sizes are especially relevant when event counts are near the maximum possible participant count or when serious events are few. A reported estimate may be numerically simple while remaining uncertain as an estimate of what might occur in a broader population. The 6mg comparison’s interval crosses zero, and the 9mg group’s equal observed count with 3mg does not prove equivalence. These are distinct statistical ideas that should not be conflated.

Finally, the registry record demonstrates the importance of reporting the analysis plan, analysis populations, missing-data approach, and methods for multiple comparisons. Without those details, readers can describe the posted results but have limited ability to audit their derivation or understand how they relate to all intended outcomes. The trial’s registry record is useful for documenting design and reported safety counts, while leaving important questions about analysis and the broader study objectives unanswered.

15. 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 primary outcome timeframe is listed as up to 24 weeks, while the official title describes a 12 Weeks Treatment Study. The registry record does not explain the relationship between treatment duration and outcome observation, so timing of exposure and ascertainment cannot be reconstructed. The endpoint description also does not provide event definitions, severity categories, attribution criteria, or event-level totals.

The trial is randomized but unmasked. The registry record does not describe sequence generation, allocation concealment, or whether outcome assessment was independent. For a participant-reported or investigator-recorded event outcome, lack of masking can be relevant to how events are elicited or classified, but the record does not provide enough detail to determine whether or how this occurred in the study.

Group sizes are limited, and the primary counts are concentrated near all participants in each group. Serious-event counts are sparse. These features make dose comparisons imprecise and constrain assessment of less common outcomes. The record does not report a formal equivalence or non-inferiority framework, so equal observed counts cannot be interpreted against such a standard.

Important analysis details are not reported in the registry record: the population analyzed, missing-data handling, statistical model or test, confidence-interval method and level, adjustment for multiple comparisons, and original sample-size rationale. The record lists four outcome measures but posts no secondary outcomes and no analyses. Thus, the safety counts do not resolve the broader pharmacokinetic and efficacy objectives. Death counts are not numeric, and the event listing does not supply enough detail to assess causes or clinical course.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Pharmacokinetic Study of MP-214 in Patients With Schizophrenia — NCT01626859.
• Registry record last updated 2026-01-05; status last verified 2025-12.
• Results first posted 2021-04-12.
• 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.

19. Record Summary

The registry record describes a completed randomized, unmasked, parallel-group study of MP-214 in patients with schizophrenia. It lists Phase 2 and Phase 3, 38 enrolled participants, and three dose groups: 3mg, 6mg, and 9mg. The study objective includes pharmacokinetics, safety, and efficacy. The primary outcome is the number of participants with adverse events over a timeframe of up to 24 weeks.

Posted primary counts are 11 of 11 for 3mg, 15 of 16 for 6mg, and 11 of 11 for 9mg. The 6mg versus 3mg comparison has a reported p-value of 0.398 and a confidence interval that crosses zero. The 9mg versus 3mg comparison reports a risk difference and interval of zero. Serious adverse events are listed for 0 of 11, 2 of 16, and 0 of 11 participants, respectively.

The registry record does not report secondary outcome results, pharmacokinetic or efficacy findings, analysis populations, missing-data methods, or a detailed statistical analysis plan. The posted results support description of the recorded counts, but not conclusions about causation, equivalence, or efficacy.