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 Study of the Effects of Risperdal Consta on Brain Reward Circuitry Function, Craving and Cocaine Use in Active Cocaine Dependence (NCT00385801), a randomized phase 2 study. The primary outcome is Functional MRI Activation Patterns in the Nucleus Accumbens and Amygdala in Response to Cocaine Cues.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00385801 |
| Phase | Phase 2 |
| Condition | Cocaine Dependence |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 31 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Massachusetts General Hospital |
| Results posted | Yes |
2. Clinical Question
Population
People with active cocaine dependence. The registry record lists Cocaine Dependence as the condition and describes the study as examining participants with active cocaine dependence. Enrollment was 31.
Intervention
The intervention was Risperidone Consta. The arm description specifies risperidone 1-2 mg tablets and risperidone 25 mg injections. The registry record does not specify the dosing schedule in the information available for this endpoint.
Comparator
The comparison was placebo, described as identical placebo tablets and injections. Random allocation and triple masking were recorded.
Primary question
The primary outcome concerns functional MRI activation patterns in the nucleus accumbens and amygdala in response to cocaine cues, with a 12 weeks timeframe. The broader study purpose included examining brain reward circuitry, behavioral tests, craving, and cocaine use. The registry record does not provide a numerical primary-outcome result or a calculated measure of its precision.
3. Trial Design
This was a Phase 2, randomized, triple-masked, parallel-group, placebo-controlled study sponsored by Massachusetts General Hospital. The registry record lists enrollment as 31 and the study status as completed. The recorded start was 2005-09, and primary completion was 2010-09. These dates describe the registry timeline; they do not establish how long each participant was followed.
The trial compared Risperidone Consta with placebo in people with active cocaine dependence. The intervention arm description identifies risperidone 1-2 mg tablets and risperidone 25 mg injections. The placebo arm is described as receiving identical placebo tablets and injections. The record does not give a dosing schedule, treatment duration, or further operational details about how the regimen was administered.
Randomization means that assignment to the study groups was intended to be determined by chance, which can reduce systematic differences between groups at baseline. Triple masking indicates that the record characterizes the study as masked at three levels, but it does not identify which roles were masked or explain how masking was maintained. Those details are not reported in the registry record.
The stated primary outcome was functional MRI activation patterns in the nucleus accumbens and amygdala in response to cocaine cues, with a 12 weeks timeframe. Secondary outcomes listed were cocaine craving and amygdala volume by MRI. The brief description also refers to behavioral tests and cocaine use. A detailed protocol, the full assessment schedule, and the relationship between the brief description and the registered outcome entries 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: After baseline evaluation participants began treatment with oral risperidone, 1 mg per day the first week and 2 mg per day for the next 3 weeks. Electrocardiograms were repeated after 1 and 2 weeks of risperidone use. Participants with corrected QT interval (QTc) prolongation greater than 470 milliseconds at either of these occasions were excluded
Overall Study
| Stage | Placebo | Risperidone Consta |
|---|---|---|
| STARTED | 15 | 16 |
| COMPLETED | 6 | 8 |
| NOT COMPLETED | 9 | 8 |
Analysis population for the primary outcome, as defined in the registry: Measure of Dispersion/Precision not calculated, and raw data are no longer available
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.
| Characteristic | Unit | Placebo | Risperidone Consta | Total |
|---|---|---|---|---|
| Participants analysed | 15 | 16 | 31 | |
| Age, Continuous | years | 42.4 (SD 6.4) | 44.1 (SD 5.9) | 43 (SD 6.1) |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 15 | 16 | 31 |
6. Primary Endpoint
The registry lists the primary outcome as Functional MRI Activation Patterns in the Nucleus Accumbens and Amygdala in Response to Cocaine Cues, measured over 12 weeks.
| 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 is titled functional MRI activation patterns in the nucleus accumbens and amygdala in response to cocaine cues. It concerns a brain-imaging response to cue exposure, rather than a direct count of cocaine use or a rating of craving. The registry record gives a 12 weeks timeframe but does not specify a unit, a numerical parameter, or a detailed scoring method for the outcome.
In general, functional MRI is used to measure changes in brain activity associated with a task or stimulus. Comparing activation patterns during responses to cocaine cues can be relevant to a study of reward circuitry because the question concerns how the brain responds to cues associated with cocaine. This rationale explains why such an endpoint may be used; it does not establish that a particular activation pattern is beneficial or harmful.
The registry description states that a measure of dispersion or precision was not calculated and that raw data are no longer available. As a result, the posted record does not permit a numerical estimate of the primary outcome’s variability or precision. It also indicates that the primary outcome had several categories or time points and was not reduced to one comparison. Without a specific contrast and its numerical result, the endpoint cannot be interpreted as a single treatment effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the trial question and design, but it does not provide a numerical result for the primary functional MRI outcome. The endpoint description explicitly says that dispersion or precision was not calculated and that raw data are no longer available. The record also indicates that the primary outcome involved several categories or time points and was not reduced to one comparison. Consequently, there is no single posted estimate, confidence interval, or test result that can be used to quantify a difference between Risperidone Consta and placebo on the primary endpoint.
A confidence interval, in general, describes the uncertainty around an estimated effect. It helps readers distinguish an estimate that is relatively precise from one that remains compatible with a wide range of effects. No such interval for the primary outcome is reported in the registry record. No numerical primary-outcome estimate is reported either, so the magnitude and direction of any group contrast cannot be assessed from this record.
The registry lists cocaine craving and amygdala volume by MRI as secondary outcomes, while the study summary also mentions cocaine use and behavioral testing. It does not give numerical results for these measures in the registry record for this analysis. Their inclusion as outcomes should not be mistaken for evidence of a treatment effect. Nor can findings for one outcome be substituted for an absent result on another.
The adverse-event figures show zero serious adverse events recorded as affecting participants in either group. Other adverse events were recorded for 7 of 15 participants in the placebo group and 13 of 16 participants in the Risperidone Consta group. These are descriptive counts as reported; they do not by themselves establish that the groups differed because of treatment. The record does not provide event-level details, a statistical comparison, or death counts.
In general, estimates from randomized trials are interpreted by considering both the size of the observed difference and its uncertainty, along with how the outcome was defined and analyzed. Here, the missing primary estimate and precision information prevent that assessment. The registry information supports a description of the study design and the reported adverse-event counts, but it does not support a conclusion about the size, direction, or certainty of an effect on the primary outcome or the other clinical outcomes.
9. Statistical Methods Explained
What does randomization contribute?
Randomization assigns participants to study groups by chance. In general, this helps limit systematic differences in characteristics that could otherwise influence outcomes, including characteristics that were not measured. It does not guarantee that groups will be identical, especially in a study with limited enrollment. The registry identifies the allocation as randomized, but the sequence-generation method, concealment procedures, and any assessment of baseline balance are not reported in the registry record.
Randomization is a design feature, not an outcome-analysis method. The record does not specify which statistical model was used to compare groups, how baseline measurements were handled, or whether the reported analysis followed the randomized assignment. Those details matter because an analysis can estimate different quantities depending on which participants and measurements are included and how repeated or categorized outcomes are treated.
What does triple masking tell readers?
Masking is intended to reduce the influence of expectations or knowledge of assignment on study conduct and outcome assessment. This is potentially relevant to imaging and behavioral measures as well as participant-reported craving. The registry labels the trial triple-masked, but does not identify the masked roles, describe the masking process, or report whether masking was assessed. The label alone therefore does not establish how effectively masking was maintained.
Why is the endpoint definition important?
The primary outcome concerns activation patterns in the nucleus accumbens and amygdala in response to cocaine cues. An outcome framed as a pattern may involve multiple regions, conditions, or time points rather than a single scalar measurement. The registry specifically says that the primary outcome has several categories or time points and was not reduced to one comparison. Without a defined contrast, readers cannot tell which particular activation measure would represent the primary treatment comparison.
In general, a statistical analysis needs to define the outcome, comparison, and population before an effect estimate can be interpreted. A contrast might compare groups at a specified assessment or compare changes over time, but the registry record does not report which approach was planned or used. No particular contrast should be inferred from the endpoint title alone.
What is the role of precision?
Precision describes how much uncertainty surrounds an estimate. A standard error or confidence interval is commonly used to communicate it. The registry states that a measure of dispersion or precision was not calculated and that raw data are no longer available. Without variability information, an independent recalculation of uncertainty is not possible from the listed endpoint details. The registry record does not provide a numerical primary estimate or a confidence interval.
In general, variability matters because observations within a group are not all identical. If outcomes vary substantially, a group average or other summary may be estimated less precisely than when observations are more consistent. For outcomes with extra variability relative to a model’s assumptions, an analysis that fails to account for that over-dispersion can understate uncertainty. No distributional information is available for this endpoint, so it is not possible to determine whether over-dispersion was present or how it was handled.
What can be inferred from the adverse-event counts?
The registry provides counts of participants affected by serious and other adverse events in each group. Such counts are descriptive. In general, comparing event counts requires attention to group sizes, the definitions and timing of events, and the analysis method. The registry entries do not include an inferential comparison or event-level breakdown. No statistical significance or causal attribution can be derived from the counts alone.
For the primary endpoint, there is no reported effect estimate or precision measure to recalculate. Any recalculation from summary statistics would require those statistics, and they are not available in the registry record. A planning illustration based on an observed effect would also not be the trial’s original design justification or observed power. The registry record does not report a sample-size justification, a statistical analysis plan, or interim-analysis procedures.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome is described as involving several categories or time points, and the record indicates that it was not reduced to one comparison. When an analysis considers multiple outcomes, regions, categories, or time points, there can be multiple opportunities to identify an apparently notable result. In general, multiplicity procedures are used to manage the interpretation of such multiple comparisons. The registry record does not report whether any adjustment was planned or applied, how the primary contrast was selected, or how the several categories or time points were handled.
The record lists secondary outcomes of cocaine craving and amygdala volume by MRI. The study summary also refers to cocaine use and behavioral tests. A complete account of the analysis would identify the measures, time points, analysis populations, and any hierarchy among outcomes. Those details are not reported in the registry record. The record does not state whether analyses were exploratory or confirmatory, or whether an analysis plan specified how secondary outcomes would be interpreted.
Missing-data procedures and analysis populations are also not reported in the registry record. The available information does not say how many participants contributed primary-outcome measurements, whether any measurements were unavailable, how missing observations were handled, or whether analysis followed randomized assignment. The statement that raw data are no longer available concerns the availability of data for calculating endpoint precision; it does not by itself establish whether participant-level measurements were missing during the original study.
Because these analytic details are absent, readers cannot assess the impact of outcome selection, missing measurements, or population definitions on the primary result. These are limitations of what can be established from the registry record, not evidence that a particular method was or was not used.
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 |
|---|---|---|---|
| Placebo | 0 | 15 | 0.0% |
| Risperidone Consta | 0 | 16 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo | 7 of 15 |
| Risperidone Consta | 13 of 16 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | Risperidone Consta |
|---|---|---|---|
| Fatigue | General disorders | 3 of 15 | 9 of 16 |
| Somnolence | General disorders | 2 of 15 | 9 of 16 |
| Dry mouth | General disorders | 4 of 15 | 6 of 16 |
| Other | General disorders | 3 of 15 | 7 of 16 |
| Increased thirst | General disorders | 4 of 15 | 4 of 16 |
| Sexual dysfunction | Reproductive system and breast disorders | 1 of 15 | 4 of 16 |
| Dizziness | General disorders | 2 of 15 | 3 of 16 |
| Dyspepsia | Gastrointestinal disorders | 3 of 15 | 2 of 16 |
| Muscle rigidity, twitches | Nervous system disorders | 1 of 15 | 4 of 16 |
| Common cold | Respiratory, thoracic and mediastinal disorders | 0 of 15 | 4 of 16 |
The serious adverse-event counts are 0 of 15 participants at risk in the placebo group and 0 of 16 participants at risk in the Risperidone Consta group. The registry lists no serious adverse-event terms. The figures describe what was recorded in the registry; they do not prove that no serious event occurred outside the reported information or establish comparative safety.
For other adverse events, the record reports 7 of 15 participants affected in the placebo group and 13 of 16 in the Risperidone Consta group. These are counts of participants with an event, not counts of all event episodes. The registry information does not provide the specific non-serious event terms, severity distribution, timing, duration, or a statistical comparison. The counts should therefore be read descriptively rather than as a tested treatment contrast.
Death counts are not reported in the registry record. The adverse-event information also does not explain how events were collected or whether participants had equal observation time. Those details can affect interpretation of event counts. No causal conclusion about an individual event or a difference between groups follows from these figures alone.
12. What the Result Does, and Does Not, Mean
This trial record describes a randomized, triple-masked, parallel, placebo-controlled study of Risperidone Consta in people with active cocaine dependence. Its primary question focused on functional MRI activation patterns in the nucleus accumbens and amygdala in response to cocaine cues. The endpoint timeframe was 12 weeks. The broader aims included brain reward circuitry, behavioral testing, craving, and cocaine use.
What the posted information does establish is the study design, the named outcomes, and the adverse-event counts. It reports zero participants with serious adverse events in each group, other adverse events affecting 7 of 15 participants in the placebo group and 13 of 16 participants in the Risperidone Consta group, and no listed serious adverse-event terms. These are registry descriptions, not a comparative statistical analysis.
What the record does not establish is the magnitude or direction of a primary-outcome difference. It reports no numerical estimate or precision measure for the functional MRI endpoint, and the raw data are no longer available. The endpoint also includes several categories or time points without a single comparison specified. As a result, the information does not show how the groups compared on the primary outcome, how uncertain any difference was, or whether the result was compatible with a range of effects.
The same caution applies to craving, amygdala volume, cocaine use, and behavioral measures: their presence in the study description is not a numerical result. No conclusion about whether treatment changed these outcomes can be drawn in the registry record reported in the registry record. The adverse-event counts likewise cannot establish a causal difference in safety.
In general, a clinical trial result is interpreted by combining the estimated effect, its uncertainty, the outcome definition, and the analysis methods. Here, important pieces of that assessment are not reported. The record therefore supports a clear account of what was studied, but not a conclusion about treatment effects.
13. Why This Trial Matters Statistically
This study is statistically notable because its main endpoint is an imaging measure described as activation patterns across brain regions in response to cocaine cues. Such outcomes can involve multiple measures or time points, and the registry explicitly notes that the primary outcome was not reduced to one comparison. That makes the exact definition of the contrast especially important for interpreting an estimated effect.
The record also illustrates why a point estimate and its precision are both needed. A numerical difference without information about variability can be difficult to interpret, while an uncertainty measure without a clearly defined contrast would also be inadequate. In this case, the registry says precision was not calculated and raw data are no longer available. That prevents readers from assessing how stable or uncertain a primary-outcome estimate might be.
Randomization and masking are important design features, but they cannot replace outcome reporting. A randomized, triple-masked design can help reduce certain sources of bias, yet interpretation still depends on transparent reporting of the outcome definition, analysis population, statistical model, and results. The registry record does not report many of these analysis details.
The reported adverse-event counts show another distinction useful for statistical reading: descriptive counts are not the same as a formal comparison. The counts can be reported accurately without implying a tested difference or a causal explanation. Taken together, the record demonstrates how a trial may be described in detail at the design level while leaving the statistical evidence needed to quantify its primary result unavailable.
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 for interpreting the primary outcome is the absence of a numerical effect estimate and a calculated measure of dispersion or precision. The registry states that raw data are no longer available. It also indicates that the primary outcome involved several categories or time points and was not reduced to one comparison. These features prevent a single quantitative treatment contrast from being reconstructed from the information reported.
The endpoint entry does not specify a unit, parameter, or detailed scoring method. The registry record does not explain the imaging analysis, the selected regions or contrasts beyond the named areas, or how any categories and time points were combined. A protocol or analysis plan describing those choices is not reported in the registry record.
Important design and analysis details are also absent. The record does not report the randomization procedure, allocation concealment, which roles were masked, how masking was maintained, the sample-size justification, the statistical model, or interim analyses. It does not identify analysis populations, missing-data methods, or multiplicity procedures. These omissions limit assessment of the robustness and interpretation of any analysis.
The safety information is limited to participant counts for serious and other adverse events. Event-level descriptions for other adverse events, death counts, timing, and inferential comparisons are not reported in the registry record. The study summary mentions outcomes beyond the primary imaging endpoint, but numerical results for those outcomes are not available in the registry record used for this analysis.
Finally, enrollment was 31, and the record does not provide enough information to judge the precision of the outcome estimates from the original analysis. No assumption about the trial’s intended power or its statistical plan can be made from the posted information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study of the Effects of Risperdal Consta on Brain Reward Circuitry Function, Craving and Cocaine Use in Active Cocaine Dependence — NCT00385801.
- Registry record last updated 2017-04-28; status last verified 2017-03.
- Results first posted 2017-04-28.
- 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
NCT00385801 was a completed Phase 2 randomized, triple-masked, parallel, placebo-controlled study sponsored by Massachusetts General Hospital. Enrollment was 31. The recorded start was 2005-09, and primary completion was 2010-09.
The study compared Risperidone Consta, described as risperidone 1-2 mg tablets and risperidone 25 mg injections, with identical placebo tablets and injections in people with active cocaine dependence. The primary outcome was functional MRI activation patterns in the nucleus accumbens and amygdala in response to cocaine cues, with a 12 weeks timeframe. Listed secondary outcomes included cocaine craving and amygdala volume by MRI.
The registry record states that primary-outcome dispersion or precision was not calculated and that raw data are no longer available. It does not provide a single primary comparison or numerical effect estimate. Serious adverse events were recorded for 0 of 15 participants in the placebo group and 0 of 16 in the Risperidone Consta group. Other adverse events affected 7 of 15 and 13 of 16 participants, respectively. Death counts are not reported in the registry record.