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 Open-label Study to Compare Hospitalization Rates of Schizophrenic Patients Treated With Oral Antipsychotics Versus IM Depot Aripiprazole (NCT01509053), a na phase 3 study. The primary outcome is Comparison of Inpatient Psychiatric Hospitalization Rates.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01509053 |
| Phase | Phase 3 |
| Condition | Schizophrenia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Otsuka Pharmaceutical Development & Commercialization, Inc. |
| Results posted | Yes |
2. Clinical Question
The study asked whether the proportion of adult patients with schizophrenia who had at least one inpatient psychiatric hospitalization differed between two treatment periods: a retrospective period during oral antipsychotic treatment and a prospective period after switching to intramuscular depot aripiprazole. The periods of interest were Months 4-6 in each phase. The planned comparison concerned hospitalization experience, not a randomized assignment to competing treatments.
Population
Adult patients with schizophrenia in a naturalistic community setting. The official title identifies Europe, Canada and Asia as the study regions. The registry record lists enrollment of 30.
Intervention
Intramuscular depot aripiprazole during the prospective treatment phase. The intervention list also includes oral aripiprazole.
Comparator
Each patient’s retrospective hospitalization experience while receiving oral standard-of-care antipsychotic treatment. This is a historical period, not a concurrently randomized control group.
Primary question
What proportion of patients had at least one inpatient psychiatric hospitalization during Months 4-6 of the retrospective oral-treatment period, compared with Months 4-6 after the switch to depot aripiprazole?
This question is framed as a within-study comparison of two periods, but the registry record does not establish that every participant contributed complete information to both periods. It also does not report an evaluated primary endpoint result. Therefore, the planned clinical comparison cannot be answered from the posted primary outcome. The study’s description identifies a naturalistic setting, so the question concerns treatment and hospitalization experience in routine community care rather than a tightly controlled randomized comparison.
3. Trial Design
The registry identifies this as a Phase 3, open-label, single-group study, with allocation listed as not applicable and masking listed as none. Those design features mean the registry does not describe randomized assignment or blinded assessment. The planned comparison uses a retrospective period on oral standard-of-care antipsychotic treatment and a prospective period after switching to intramuscular depot aripiprazole. For the primary endpoint, both periods focus on Months 4-6; the description also gives the corresponding week ranges as Weeks-12 to -24 and Weeks 12 to 24.
The study began in 2012-01, had a primary completion date of 2012-10, and is marked terminated. Enrollment is listed as 30. The registry says the sponsor terminated the study early and that the low number enrolled meant the primary efficacy endpoint was not evaluated. The record does not report why the study was terminated beyond those stated circumstances.
The oral-treatment period is historical, while the depot-treatment period is prospective. As a result, the comparison is not a like-for-like randomized control comparison: treatment period, time, and how information was collected are linked. Differences between periods could reflect more than treatment, including changes in participants’ circumstances or care. This is a general design consideration, not a finding about what occurred in this study.
The arm description indicates that patients without a history of tolerability to oral aripiprazole received oral aripiprazole for a tolerability assessment before depot treatment. The listed dose was 10-15 mg/day, up to 30 mg/day, for 1 to 4 weeks. The arm description is incomplete in the registry record, so further details of treatment delivery are not reported there. The record also lists secondary outcomes concerning PANSS scores and Clinical Global Impression scores, but it does not report evaluated results for those measures in the material described by the registry entry.
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: This study included a Tolerability Assessment Phase A (if applicable), an Open-Label Aripiprazole IM Depot Phase B and an Open-Label Aripiprazole IM Depot Extension Phase C.
Oral Aripirazole (Phase A)
| Stage | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| STARTED | 19 |
| COMPLETED | 8 |
| NOT COMPLETED | 11 |
Reasons for not completing this period:
| Reason | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| Sponsor discontinued study | 11 |
Aripiprazole IM Depot Treatment Phase(B)
| Stage | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| STARTED | 19 |
| COMPLETED | 3 |
| NOT COMPLETED | 16 |
Reasons for not completing this period:
| Reason | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| Adverse Event | 1 |
| Sponsor discontinued study | 13 |
| Subject was withdrawn by investigator | 1 |
| Subject withdrew consent | 1 |
Aripiprazole IM Depot Extension Phase(C)
| Stage | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| STARTED | 3 |
| COMPLETED | 0 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Oral Aripiprazole Tablets and Aripiprazole IM Depot Injection |
|---|---|
| Sponsor discontinued study | 3 |
Analysis population for the primary outcome, as defined in the registry: Due to the low number of enrolled patient and the sponsor's early termination of the study, the primary efficacy endpoint was not evaluated.
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: Baseline measures are based on all enrolled participants.
| Characteristic | Unit | All Participants |
|---|---|---|
| Participants analysed | 30 | |
| Age, Continuous | years | 43.9 (SD 12.4) |
| Sex: Female, Male: Female | Participants | 10 |
| Sex: Female, Male: Male | Participants | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Comparison of Inpatient Psychiatric Hospitalization Rates, measured over Retrospective period Months 4-6; Prospective period Months 4-6.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the proportion of patients with at least one inpatient psychiatric hospitalization during the specified period. It compares the retrospective Months 4-6 while patients were receiving oral standard-of-care antipsychotic treatment with prospective Phase B Months 4-6 after the switch to intramuscular depot aripiprazole.
Although the endpoint title uses the word hospitalization rates, its description defines a patient-level proportion: whether each patient had one or more inpatient psychiatric hospitalizations during the period. It is not described as the total number of admissions, the number of hospital days, or time until a first admission. The binary definition makes the outcome straightforward to interpret as the share of patients experiencing any hospitalization in each period.
As a general statistical point, hospitalization can be a meaningful measure of serious mental-health service use, but it also reflects access to care, admission practices, and other features of the care setting. A period comparison can describe differences in the observed proportions, but by itself it does not establish why those differences occurred. Here, the registry record states that the primary endpoint was not evaluated because enrollment was low and the study was terminated early. A primary endpoint estimate is therefore not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the registry record says the primary efficacy endpoint was not evaluated. Consequently, there is no reported primary comparison of hospitalization proportions for the retrospective oral-treatment period and the prospective depot-treatment period. The registry does not report an effect estimate, a confidence interval, or a hypothesis-test result for this endpoint. The planned clinical question remains unanswered by the posted primary outcome.
This absence should not be read as evidence that the two periods had identical hospitalization experience, nor as evidence that one period had better or worse outcomes. An endpoint that was not evaluated yields no result with which to assess the size, direction, or precision of a difference. It also does not establish that no hospitalizations occurred. The enrollment figure of 30 describes the study enrollment, not the number contributing to a completed primary analysis.
The design further limits causal interpretation. The study is described as single-group and open-label, with no allocation and no masking. The treatment periods are sequentially structured, and the earlier period is retrospective while the later period is prospective. In general, an observed before-and-after difference in such a design could reflect treatment, changes over time, differences in record capture, or other factors. Because the primary endpoint was not evaluated, the registry offers no observed primary result to interpret in light of these possibilities.
The adverse-event listings are separate from the primary efficacy endpoint. They report serious adverse events for the listed treatment phases, as well as other adverse events, but those counts do not answer the hospitalization comparison. The registry lists 19 at risk in Oral Aripiprazole (Phase A), 19 in Aripiprazole IM Depot (Phase B), and 3 in Aripiprazole IM Depot (Phase C). These safety denominators are not a substitute for an analysis population for the primary endpoint, which is not reported in the registry record.
Interpretation should also distinguish observed information from planned analysis. The record identifies the hospitalization outcome and the periods intended for comparison, but does not report a statistical analysis of that endpoint. It does not report the analysis population, handling of incomplete observations, or an inferential procedure. Those omissions prevent assessment of the precision or robustness of a primary comparison. The appropriate conclusion is limited: the study planned to compare hospitalization proportions across the two periods, but the registry states that the primary endpoint was not evaluated.
9. Statistical Methods Explained
The registry describes a planned comparison of a binary outcome across two treatment periods, but it does not report an analysis method for the primary endpoint. The statistical concepts below explain how such an endpoint is generally interpreted; they do not describe a method confirmed to have been used in this study.
What does a patient-level proportion represent?
The endpoint classifies each patient according to whether at least one inpatient psychiatric hospitalization occurred during a defined period. A proportion is the number of patients meeting that definition relative to the number assessed for that period. It does not count multiple admissions separately: a patient with one admission and a patient with more than one admission both meet the endpoint definition. This makes the measure a summary of whether any hospitalization occurred, not of hospitalization frequency or duration.
Comparisons of proportions are often expressed as an absolute difference, a relative measure, or both. Each communicates a different aspect of the comparison. An absolute difference describes the change in the share of patients; a relative measure expresses one share in relation to another. Neither is available for this primary endpoint because the registry says it was not evaluated. No new comparison can be calculated from the enrollment figure alone.
Why does the period structure matter?
The primary outcome description pairs a retrospective Months 4-6 period on oral standard-of-care antipsychotic treatment with prospective Phase B Months 4-6 after switching to depot aripiprazole. If the same patients contribute observations in both periods, their outcomes are paired rather than independent. In general, paired analyses account for the fact that observations from one person may be more alike than observations from different people. A method designed for independent groups could misstate uncertainty when the same people are measured repeatedly.
The registry does not report whether all patients contributed data for both periods or how incomplete pairs would be handled. It also does not report a statistical test or model. The record therefore does not establish whether any paired approach, independent-groups approach, or another method was used. The outcome description identifies the intended comparison, not the analysis procedure.
What does a confidence interval mean?
In general, a confidence interval describes the uncertainty around an estimated quantity under a specified statistical method. A narrow interval indicates greater precision, while a wide interval indicates less precision. An interval that includes values corresponding to no difference can be compatible with a range of possible effects, including some in either direction. A confidence interval does not correct for study-design limitations or unmeasured differences between periods. No confidence interval for the primary endpoint is reported in the registry record because that endpoint was not evaluated.
Why is the design relevant to inference?
Randomization, when used, can help balance measured and unmeasured factors between concurrent treatment groups. This study is listed as single-group, with allocation not applicable, and the treatment periods are historical and prospective rather than randomized concurrent arms. General causal interpretation is therefore limited: any contrast could be influenced by period effects, differences in care or records, and other factors as well as treatment. Open-label conduct also means masking was absent, as the registry records. This does not prove that assessment was biased; it identifies a design feature that readers should consider.
What can planning calculations establish?
Sample-size planning calculations are prospective illustrations of how much information might be needed under specified assumptions. They are not observed trial results and do not tell whether a study actually had a particular probability of detecting an effect after the fact. The registry gives assumptions for a planning illustration: two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect described as a stated fraction of the observed effect. Those assumptions do not establish that they were the trial’s original design plan. No sample-size justification is reported in the registry record.
For outcomes based on event counts or time to event, statistical methods may need to account for the event process and exposure time. Over-dispersion is a general concern in count-data models when observed variability exceeds what a model assumes; ignoring it can lead to uncertainty estimates that are too optimistic. The primary endpoint is defined as a patient-level proportion, not a count of repeated admissions or a time-to-event outcome, and the registry does not report that a count or time-to-event model was applied. These general concepts should not be mistaken for the study’s actual statistical plan.
Overall, the statistical description establishes the endpoint definition and the intended periods, but not the analysis used, the estimate, or its precision. The primary endpoint was not evaluated, and the analysis method is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists secondary outcomes for change from baseline in PANSS total score, PANSS positive and negative subscale scores, Clinical Global Impression of Severity, and Clinical Global Impression of Improvement. Along with the primary hospitalization endpoint, these are the outcome measures identified in the record. The primary endpoint was not evaluated because of low enrollment and early termination. The registry does not report evaluated results for the listed secondary outcomes in the record.
When a study examines multiple outcomes or makes multiple comparisons, the chance of at least one apparently unusual result can increase. Statistical procedures for multiplicity can control that risk, but they may also affect the interpretation and precision of individual comparisons. This is a general statistical consideration. A multiplicity adjustment plan, hierarchy among endpoints, or other strategy for interpreting multiple tests is not reported in the registry record. The number of analyses is listed as 0.
The record does not report the analysis populations, rules for inclusion in each outcome analysis, or handling of missing observations. It therefore does not establish whether the primary outcome was intended to use all enrolled patients, only patients with observations in both periods, or another population. No imputation method, missing-data sensitivity analysis, or account of incomplete follow-up is reported. Because the primary endpoint was not evaluated, readers cannot assess how missing observations might have affected its estimate. These reporting gaps are distinct from the stated reason for not evaluating the endpoint: low enrollment and early termination.
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 |
|---|---|---|---|
| Oral Aripiprazole (Phase A) | 0 | 19 | 0.0% |
| Aripiprazole IM Depot (Phase B) | 1 | 19 | 5.3% |
| Aripiprazole IM Depot (Phase C) | 0 | 3 | 0.0% |
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 |
|---|---|
| Oral Aripiprazole (Phase A) | 4 of 19 |
| Aripiprazole IM Depot (Phase B) | 10 of 19 |
| Aripiprazole IM Depot (Phase C) | 1 of 3 |
Most frequent serious adverse event terms
| Event term | Organ system | Oral Aripiprazole (Phase A) | Aripiprazole IM Depot (Phase B) | Aripiprazole IM Depot (Phase C) |
|---|---|---|---|---|
| Drug-induced liver injury | Hepatobiliary disorders | 0 of 19 | 1 of 19 | 0 of 3 |
| Schizophrenia | Psychiatric disorders | 0 of 19 | 1 of 19 | 0 of 3 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Oral Aripiprazole (Phase A) | Aripiprazole IM Depot (Phase B) | Aripiprazole IM Depot (Phase C) |
|---|---|---|---|---|
| Insomnia | Psychiatric disorders | 3 of 19 | 3 of 19 | 0 of 3 |
| Fatigue | General disorders | 1 of 19 | 2 of 19 | 0 of 3 |
| Diabetes mellitus | Metabolism and nutrition disorders | 0 of 19 | 1 of 19 | 1 of 3 |
| Somnolence | Nervous system disorders | 1 of 19 | 1 of 19 | 0 of 3 |
| Flatulence | Gastrointestinal disorders | 0 of 19 | 1 of 19 | 0 of 3 |
| Irritability | General disorders | 0 of 19 | 1 of 19 | 0 of 3 |
| Bronchitis | Infections and infestations | 0 of 19 | 1 of 19 | 0 of 3 |
| Alanine aminotransferase increased | Investigations | 0 of 19 | 1 of 19 | 0 of 3 |
| Aspartate aminotransferase increased | Investigations | 0 of 19 | 1 of 19 | 0 of 3 |
| Blood creatine phosphokinase increased | Investigations | 0 of 19 | 1 of 19 | 0 of 3 |
Serious events with the highest arm-level rate: drug-induced liver injury (5.3%), schizophrenia (5.3%).
The safety listings separate serious adverse events from other adverse events and give at-risk counts for each listed phase. Oral Aripiprazole (Phase A) lists 19 at risk, 0 with a serious adverse event, and 4 with other adverse events. Aripiprazole IM Depot (Phase B) lists 19 at risk, 1 with a serious adverse event, and 10 with other adverse events. Aripiprazole IM Depot (Phase C) lists 3 at risk, 0 with a serious adverse event, and 1 with other adverse events.
These are descriptive counts, not a randomized safety comparison. The phases have different listed at-risk counts, and the study is not a like-for-like control comparison. The registry also lists Drug-induced liver injury and Schizophrenia among the top serious adverse event terms, each at 5.3%. It does not identify the phase associated with each listed term in this summary, so the terms should not be assigned to a phase from these figures.
Death counts are not reported in the registry record. The serious-event counts describe the entries as listed; they do not by themselves establish causation or provide a precise estimate of comparative risk. Small at-risk groups also mean that these counts should be read as a limited descriptive safety record, not as proof that an event cannot occur.
12. What the Result Does, and Does Not, Mean
The study’s primary question was whether the proportion of patients with at least one inpatient psychiatric hospitalization differed between a retrospective oral-treatment period and a prospective period after switching to intramuscular depot aripiprazole. The registry record states that the endpoint was not evaluated because the number enrolled was low and the sponsor terminated the study early. No primary result is available to quantify the comparison.
That means the posted record does not show whether the hospitalization proportions were similar or different, the direction of any difference, or how precisely such a difference could have been estimated. It does not support a conclusion about benefit or lack of benefit. A missing primary result is not equivalent to a finding of no effect, and it cannot be converted into evidence that the periods had the same outcome.
The study design also matters for what a result could have meant. The registry describes a single-group, open-label study with a historical period and a prospective period, not randomized concurrent treatment groups. In general, a difference across periods in such a design could have more than one explanation. Even if a comparison had been reported, the design would require caution in attributing a change specifically to treatment.
The safety counts provide descriptive information for the listed phases, but they do not answer the primary hospitalization question and do not constitute a controlled safety comparison. The registry’s adverse-event terms and counts should be read within their recorded denominators and phase labels. The record does not report death counts or a complete primary analysis population.
The most defensible interpretation is therefore about the limits of the available evidence: a comparison was planned, but the registry says its primary endpoint was not evaluated. The record documents study design and some safety summaries, but it does not establish a comparative hospitalization result.
13. Why This Trial Matters Statistically
This trial is statistically instructive because its stated clinical question and its available result are not the same thing. A clearly defined endpoint does not guarantee that an estimate will be produced. Here, the primary outcome is described as a patient-level proportion over specified periods, but the registry states that it was not evaluated after low enrollment and early termination. Statistical interpretation must begin by distinguishing a planned comparison from a completed analysis.
The design also illustrates why a before-and-after comparison is not interchangeable with a randomized comparison. The retrospective and prospective periods differ in timing and in how the information was collected. In general, that structure makes it difficult to separate treatment-related changes from changes over time or other influences. The record’s open-label, single-group description makes the limits of causal inference important even before considering the missing primary result.
There is a further lesson in denominator interpretation. The adverse-event listings give phase-specific at-risk counts, while enrollment describes the study as a whole. Those figures serve different purposes and should not be treated as interchangeable analysis populations. The primary endpoint population and handling of incomplete data are not reported in the registry record.
Finally, the study highlights the difference between an unreported or unevaluated outcome and a null finding. Without an endpoint estimate and its uncertainty, readers cannot assess the magnitude or precision of the intended comparison. Careful statistical reading therefore avoids both overclaiming and treating missing evidence as evidence of no difference.
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 limitation is explicit in the registry record: low enrollment and early termination meant that the primary efficacy endpoint was not evaluated. The study lists enrollment of 30, but the record does not report a completed primary analysis or its result. The reasons for low enrollment and the sponsor’s decision to terminate beyond the stated circumstances are not reported in the registry record.
The planned comparison is not randomized. It contrasts a retrospective oral-treatment period with a prospective period after switching to depot aripiprazole. The registry identifies the study as single-group, open-label, with allocation not applicable and masking none. General concerns include time-related differences and differences in how retrospective and prospective information is captured. The registry does not report procedures that would address such concerns.
The primary analysis population, completeness of paired observations, missing-data methods, statistical model, confidence intervals, and hypothesis-testing approach are not reported in the registry record. The rationale for the planned sample size and any interim-analysis plan are also not reported. The registry does not provide enough information to judge whether the planned comparison could have been estimated precisely had it been evaluated.
Safety summaries have limited interpretive scope as well. The listed phases have different at-risk counts, and no randomized control comparison is described. The death counts and the phase attribution of the listed top serious adverse-event terms are not reported in the registry record. These limitations mean that the safety counts should be read descriptively rather than as a basis for a comparative conclusion.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Open-label Study to Compare Hospitalization Rates of Schizophrenic Patients Treated With Oral Antipsychotics Versus IM Depot Aripiprazole — NCT01509053.
- Registry record last updated 2015-03-04; status last verified 2015-02.
- Results first posted 2014-01-16.
- 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
This Phase 3 study enrolled 30 and is listed as terminated. It was open-label and single-group, with a planned comparison of retrospective hospitalization experience during oral standard-of-care antipsychotic treatment and prospective experience after switching to intramuscular depot aripiprazole. The primary outcome was the proportion of patients with at least one inpatient psychiatric hospitalization during Months 4-6 in each period.
The registry states that the primary efficacy endpoint was not evaluated because of low enrollment and early termination. It lists secondary symptom and clinical-impression outcomes and phase-specific adverse-event counts, but no primary hospitalization result. Statistical analysis methods, analysis populations, and missing-data procedures are not reported in the registry record.