An Efficacy and Safety Study of Risperidone Long-Acting Microspheres in Participants With Schizophrenia, Schizophreniform or Schizoaffective Disorders: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An Efficacy and Safety Study of Risperidone Long-Acting Microspheres in Participants With Schizophrenia, Schizophreniform or Schizoaffective Disorders (NCT01855074), a na phase 4 study. The primary outcome is Change From Baseline in Positive and Negative Syndrome Scale (PANSS) Total Score at Week 26.

2. Clinical Question

In statistical terms, the study’s primary question concerns the average within-participant change over follow-up, not a difference between treatment groups. Because there is no concurrent comparator, the study cannot use its design to estimate how outcomes would have differed under another treatment or under no switch. Its stated focus was efficacy and safety after switching treatment, while the primary measure captures symptom severity at baseline and Week 26.

3. Trial Design

This was a completed Phase 4 study with a single-group model, allocation listed as NA, and no masking. The registry record lists enrollment as 80. It identifies Janssen-Cilag Ltd. as the sponsor, a start date of 2007-11, and primary completion in 2009-02. These registry entries describe the study record; they do not establish how many participants contributed data to the primary outcome at each assessment.

Participants with schizophrenia, schizophreniform disorder, or schizoaffective disorder received long-acting risperidone microspheres after switching from antipsychotic therapy. The regimen description states 25 mg by intramuscular injection every 2 weeks for up to 6 months. Participants with persistent symptoms and/or requiring higher antipsychotic doses could receive higher risperidone doses, adjusted at investigator discretion. This allowance means treatment exposure was not necessarily identical for every participant.

A single-group design observes outcomes under the study treatment but does not include a contemporaneous treatment arm to provide a direct contrast. Any change from baseline is therefore a within-group measure. It may describe the course of scores during the study, but it cannot by itself separate treatment-associated change from other influences, such as changes over time, expectation, or concurrent care. Those are general design considerations, not findings established for these participants.

The primary outcome was change in PANSS total score at Week 26. Named secondary measures cover clinical global severity, quality of life, functioning, satisfaction with treatment, and extrapyramidal symptoms. The registry record does not describe a masking procedure, a random allocation scheme, a control regimen, or a statistical analysis plan. The exact visit schedule beyond the stated baseline and Week 26 primary time points 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Intent-to-treat (ITT) population included all the participants who received at least 1 dose of study medication and had at least 1 follow-up visit. Here 'n' signifies number of participants evaluable for this outcome measure at specific time point.

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 Change From Baseline in Positive and Negative Syndrome Scale (PANSS) Total Score at Week 26, measured over Baseline and Week 26.

The Positive and Negative Syndrome Scale (PANSS) is described in the registry as a 30-item measure of symptoms associated with schizophrenia. Its items include delusions, grandiosity, blunted affect, poor attention, and poor impulse control. Each symptom is rated from 1, absent, to 7, extreme psychopathology. The total is the sum of the item ratings and ranges from 30 to 210; higher scores indicate worsening.

The primary endpoint is change from baseline in PANSS total score at Week 26. In this record, the change is calculated as baseline score minus Week 26 score. The direction is therefore important: a positive change means the Week 26 total is lower than the baseline total, while a negative change means it is higher. This description explains the scale’s direction; it does not indicate which direction the observed study result took.

A total score combines information across the scale’s symptoms into a continuous measure. Summarizing change with a mean can describe the average score movement among participants evaluated. A standard deviation describes how dispersed individual scores or changes are around that mean; it is not the same as the precision of the mean. The numerical mean change, standard deviation, and outcome-specific participant count are not reported in the registry record.

The endpoint is used to assess symptom severity over time. Its interpretation in this study is limited to change within the single group and to the specified assessment period. The registry does not report a comparison against another group or a threshold for interpreting the size of an individual change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation depends first on identifying what was measured and how the study was structured. Here, the primary measure is a continuous PANSS total score, and the study model is single-group. The registry specifies a mean and standard deviation for the primary outcome, but does not report their numerical values. No inferential analysis results are listed in the record.

What does a mean change represent?

In general, a mean change is the arithmetic average of participants’ changes between the specified assessments. It summarizes the central tendency of those individual changes, rather than describing every participant’s experience. A mean can be influenced by particularly large or small changes, so it is useful to consider it alongside a measure of spread and, where available, a confidence interval. The registry’s endpoint description specifies a mean and standard deviation, but the numerical estimate and standard deviation are not reported in the registry record.

The endpoint uses baseline minus Week 26, rather than Week 26 minus baseline. That choice determines the sign. Since higher PANSS scores indicate worsening, a positive value under this definition corresponds to a lower follow-up score. Clear interpretation requires using the stated subtraction order rather than assuming a conventional direction from the word change alone.

What does the standard deviation tell readers?

In general, the standard deviation describes how spread out observed values are around their mean. A larger standard deviation indicates greater variability among those observations, while a smaller one indicates less spread. It does not directly express uncertainty about the mean. The standard error and a confidence interval address uncertainty in an estimated mean, and their calculation depends on the available observations and analysis assumptions. The registry record does not report a standard error, confidence interval, or the participant count evaluated for the primary outcome.

A confidence interval, in general, gives a range of estimates compatible with the data and the method used to construct it. Its width communicates precision: wider intervals indicate less precision than narrower intervals under the same method. It does not show the range of individual participant outcomes. No confidence interval for the primary outcome is reported in the registry record, so the precision of the mean change cannot be assessed from the reported primary endpoint information.

Why does the study model matter?

With one group, an average baseline-to-follow-up change describes observed change within that group. In general, a concurrent comparator can help estimate the difference in outcomes between treatment strategies over the same period. Without such a group, the within-group change does not isolate the treatment’s contribution. For example, time trends, expectations, other care, or selective follow-up can affect observed change in general; the record does not establish whether any of these affected this study.

The lack of masking is also relevant as a general design consideration. When participants and investigators know which treatment is being used, subjective assessments or reported experiences can be susceptible to expectations. This does not establish that bias occurred, but it is one reason to interpret an unmasked study’s subjective measures in light of its design. No masking method is reported, and the record explicitly lists masking as none.

How should the planning illustrations be read?

In general, sample-size planning asks how many participants a future study might need under specified assumptions about the effect to detect, significance level, allocation, and statistical model. These calculations are planning illustrations, not observed results and not evidence that a study had a particular probability of detecting an effect. The registry’s stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is framed as a stated fraction of the observed effect. For non-time-to-event outcomes, the stated convention is participants per arm.

Those assumptions describe a hypothetical two-arm planning setup, whereas the study itself is single-group and has no randomized comparator. The assumptions should not be mistaken for the trial’s own design or statistical plan. The registry says the illustrations use the observed effect, but the numerical primary effect is not reported in the record. Without the relevant numerical calculation, the planning output cannot be independently interpreted from the registry entries alone. Such planning values, where displayed, would remain hypothetical and would not represent observed power.

What can be concluded from the posted analyses?

The analysis count is listed as 0. The record therefore does not provide a listed inferential analysis for the primary outcome. A p-value, confidence interval, adjusted estimate, or model-based result is not reported in the registry record. General statistical guidance about these methods cannot substitute for a study-specific analysis. In particular, absence of a reported test result should not be converted into a claim of statistical significance, lack of significance, or equivalence.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary PANSS outcome and secondary outcomes covering Clinical Global Impressions disease severity, SF-36 quality of life, Global Assessment of Functioning, patient satisfaction with treatment, and extrapyramidal symptoms. Considering several outcomes can raise a general multiplicity issue: when many statistical tests are conducted, the chance of at least one apparently unusual result can increase. Methods such as prespecifying a primary outcome or adjusting tests can address aspects of this issue, but the registry record does not report a multiplicity procedure or a hierarchy for interpreting secondary outcomes.

The record lists no analyses. It does not report p-values or numerical results for the listed outcome measures, and it does not say whether any planned analyses were conducted but omitted from the registry. The statistical plan, including any planned treatment of multiple outcomes, is not reported in the registry record. It is therefore not possible to determine from this record how multiplicity was handled.

The primary-outcome population description defines ITT as participants who received at least one dose and had at least one follow-up visit. This definition is part of the registry record and is not the same as including every person enrolled regardless of treatment or follow-up. The record also states that n refers to participants evaluable for the outcome at the specific time point. The actual time-specific counts are not reported in the registry record.

Missing-data methods are not reported in the registry record. It does not specify how incomplete assessments, withdrawal, or missing Week 26 measurements were handled, or whether any imputation or sensitivity analysis was used. In general, missing-data assumptions can affect an estimated mean change if participants with observed follow-up differ systematically from those without it. Without counts and methods, the extent or direction of any such influence cannot be assessed.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: psychotic disorder (1.3%).

The safety listing records 79 participants at risk for serious adverse events and one affected participant. It also records 79 at risk for other adverse events and one affected participant. The top serious term is psychotic disorder, reported as 1.3%. These entries describe the registry’s event counts; they do not provide a comparison with another treatment group.

The serious-event count and the other-adverse-event count are separate fields. The record does not establish whether the entries concern the same participant, whether they refer to different events, or how the events overlapped. They should not be added or interpreted as a count of unique participants. The death count is not reported in the registry record.

In general, an event count and a percentage have to be read with their stated at-risk population and event definitions. A small count can make an estimated event frequency imprecise, and a percentage alone does not show whether a treatment caused an event. The registry record does not describe causal attribution, event timing, duration, severity beyond the serious classification, or a comparative safety analysis for these entries. The figures therefore support only a limited descriptive reading of the reported adverse-event fields.

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

The record establishes that a completed Phase 4, single-group study evaluated long-acting risperidone microspheres in participants with schizophrenia, schizophreniform disorder, or schizoaffective disorder. It defines the primary endpoint as mean change in PANSS total score from baseline to Week 26, with change calculated as baseline minus Week 26. It also gives the PANSS score direction and describes the treatment regimen and population definition.

The record does not report a numerical mean change, standard deviation, time-specific evaluable count, or inferential analysis for the primary outcome. It therefore does not allow readers to quantify the observed average change, assess its precision, or determine whether the data met any statistical threshold. The absence of a posted numerical result is not itself evidence for or against an effect.

Even a reported within-group change would not be a direct comparison between risperidone and another treatment, because the study has no concurrent comparator. General causal interpretation of before-and-after data requires caution: observed change alone does not distinguish the contribution of treatment from other possible influences. The registry record does not report a design feature that would provide such a contrast.

The safety fields give descriptive counts and a serious-event term, but do not present comparative rates or a causal analysis. They do not establish that the treatment caused or prevented any event. Likewise, the named secondary measures identify additional domains assessed, but their results are not reported in the registry record.

Accordingly, the available record is useful for understanding the study’s question, endpoint definitions, and basic design. It is not sufficient to estimate the size or precision of the primary outcome, compare treatment strategies, or draw a comprehensive conclusion about safety. Those conclusions require numerical outcome reporting and details of the analyses and missing-data handling, which are not reported in the registry record.

13. Why This Trial Matters Statistically

This study illustrates why the design and reporting context are essential when reading a clinical outcome. A PANSS change score may be a clear measure of symptom-score movement over time, but the meaning of that movement depends on its sign convention, the participants contributing data, and whether the question is within-group change or a comparison between strategies. The registry specifies the sign convention and identifies the study as single-group, making those distinctions central to interpretation.

It also demonstrates the difference between reporting an endpoint definition and reporting an endpoint result. The record explains the scale, the scoring direction, and the Week 26 assessment, while the numerical mean change, standard deviation, and outcome-specific sample count are not reported in the registry record. Without these values, readers cannot judge the size or precision of the primary estimate. A well-defined measure does not, by itself, reveal what the study observed.

The safety entries provide another statistical lesson: event counts and percentages need context. The record gives at-risk counts and a serious-event term, but does not supply a comparator, causal attribution, or enough detail to establish how event entries relate to one another. Descriptive safety information should not be treated as a comparative effect estimate.

Finally, planning assumptions are distinct from trial results. The registry describes an illustration based on a hypothetical two-arm allocation and an effect derived from the observed effect, while the actual study is single-group. Keeping those planning assumptions separate from the design prevents readers from treating a hypothetical sample-size calculation as a trial finding or an analysis of observed power. The record is therefore a useful example of why endpoint reporting, design structure, and inferential evidence must be read together.

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 primary limitation for statistical interpretation is that the registry record does not report the numerical primary outcome. It specifies mean change and standard deviation, but provides no value for either, no outcome-specific evaluable count, and no confidence interval or test result. The record also lists no analyses. The effect’s magnitude, direction, and precision therefore cannot be assessed from the registry information.

The single-group design has no concurrent comparator, so it does not estimate a between-group treatment contrast. Changes from baseline are descriptive of the group over time and cannot, on their own, isolate treatment effects from other possible influences. The study is unmasked, and the registry does not report procedures intended to reduce assessment or expectation-related bias.

Dose adjustment was at investigator discretion, with higher doses permitted for persistent symptoms and/or a need for higher antipsychotic doses. This means the arm description allows variation in exposure; the registry does not report the distribution of doses received or how dose changes were handled in any analysis. The actual primary-outcome time-point counts and missing-data methods are also not reported in the registry record.

The record names secondary measures but does not provide their numerical findings or describe a multiplicity strategy. It does not report a statistical analysis plan, sample-size justification for the trial itself, or methods for handling incomplete outcome data. These omissions limit assessment of analytic choices and the risk of selective interpretation. The safety entries are sparse and descriptive, with no comparative group or causal assessment described. These limitations concern what can be concluded from the registry record; they do not establish that unreported methods or results were absent from other study documents.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: An Efficacy and Safety Study of Risperidone Long-Acting Microspheres in Participants With Schizophrenia, Schizophreniform or Schizoaffective Disorders — NCT01855074.
• Registry record last updated 2013-08-14; status last verified 2013-08.
• Results first posted 2013-07-25.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes a completed Phase 4, unmasked, single-group study of long-acting injectable risperidone in participants with schizophrenia, schizophreniform disorder, or schizoaffective disorder. Enrollment is listed as 80. The regimen description specifies 25 mg intramuscularly every 2 weeks for up to 6 months, with investigator-directed dose adjustment and higher doses permitted for persistent symptoms and/or higher antipsychotic requirements.

The primary endpoint is mean change in PANSS total score from baseline to Week 26, calculated as baseline minus Week 26. The registry defines the ITT population as participants who received at least one dose and had at least one follow-up visit, while outcome-specific n refers to those evaluable at each time point. The numerical primary result, outcome-specific counts, and analyses are not reported in the registry record.

The listed safety fields record one serious adverse event among 79 at risk, one other adverse event among 79 at risk, and psychotic disorder as the top serious term at 1.3%. The death count is not reported in the registry record. No concurrent control group is described, so the study does not provide a randomized comparison.