Psychopharmacology for Cocaine Dependence - Buspirone: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Psychopharmacology for Cocaine Dependence - Buspirone (NCT01267292), a randomized phase 2 study. The primary outcome is Attentional Bias as Assessed by Score on the Stroop Task.

2. Clinical Question

The study was designed to characterize subjective, cardiovascular, and behavioral responses associated with buspirone in people with cocaine dependence. Its registered primary endpoint focused specifically on attentional bias to cocaine-related words relative to neutral words. The registry’s background describes interest in whether buspirone might attenuate effects associated with a stimulant challenge, but that rationale is not itself evidence of an observed effect.

The endpoint description covers four time points and four methylphenidate dose levels, including a zero-dose placebo condition. It says each participant contributed a data point at each dose level and that the reported score was averaged over the four time points. Because results for the different dose levels and comparisons are not reported in the registry record, the primary question cannot be reduced to one numerical contrast from the posted information.

3. Trial Design

The registry classifies this as a Phase 2, randomized, triple-masked, parallel-design trial. The listed enrollment is 50, and the status is completed. The record gives a start date of 2011-03 and a primary completion date of 2015-12. The sponsor is The University of Texas Health Science Center, Houston.

The two described groups are Buspirone plus Methylphenidate and Placebo for Buspirone plus Methylphenidate. The study also lists methylphenidate and placebo for methylphenidate as interventions, reflecting an acute challenge within the medication design. The arm descriptions indicate daily buspirone or its placebo and challenge sessions involving methylphenidate or its placebo. However, the descriptions are truncated, so the complete sequence, dose schedule, and administration details are not reported in the registry record.

Randomization indicates that assignment was intended to use a chance-based process; triple masking indicates that the record classifies the trial as masked at three levels, without identifying those roles in the available information. A parallel design means the registry distinguishes groups rather than describing a crossover trial. The record does not report the randomization procedure, allocation concealment method, or exactly who was masked.

The registered primary measure is continuous: a mean Stroop-task score in milliseconds, reported as a difference between reaction times to cocaine-related and neutral words. The outcome description summarizes four time points, while the planned challenge includes four methylphenidate dose levels. The record also lists 15 secondary outcome measures, including subjective-effect scales, cardiovascular measurements, and rapid response inhibition. It does not report comparative estimates for those measures.

Although the trial is marked completed, completion status alone does not establish that every planned analysis is reported. The registry record lists 0 analyses, and the primary outcome is not reduced to a single comparison because it has multiple dose categories or time points.

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

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 Attentional Bias as Assessed by Score on the Stroop Task, measured over 1 time a day on Wednesday and Friday of week 2; 1 time a day on Monday and Wednesday of week 3.

The primary endpoint is attentional bias measured with the Stroop task. Participants respond to words presented in different colors by selecting a corresponding colored button. The task compares reaction times for cocaine-related words with reaction times for neutral words, producing a difference score in milliseconds.

A positive score means slower responding to cocaine-related words and therefore greater attentional bias, as defined by the registry. A negative score is described as indicating no attentional bias to cocaine words. This operational definition matters: the score is not a direct measure of cocaine use, dependence severity, or clinical benefit. It represents a difference in task response speed under the tested conditions.

The registry says the reported score is a mean over four measurement times. It also describes one data point per participant for each methylphenidate dose level: 15mg, 30mg, 60mg, or 0mg. The outcome timeframe places measurements on Wednesday and Friday of week 2 and Monday and Wednesday of week 3. Thus, the measure was intended to characterize a response across repeated time points and challenge conditions, rather than to capture a single isolated reaction-time assessment.

Stroop tasks are used in research because response delays to selected categories of words can operationalize attentional bias. That is a general measurement rationale, not proof that any particular score predicts behavior outside the task. The registry record does not report the observed scores, the variability around them, or a comparison estimate. Consequently, the magnitude and precision of any difference between the buspirone and placebo conditions cannot be assessed from the posted outcome information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous mean, expressed in milliseconds, with standard deviation as its stated measure of dispersion. Understanding these quantities helps distinguish the location of the scores from their spread. The registry record does not include the actual means or standard deviations, so these concepts explain how results would be read rather than describe observed trial findings.

What does the mean represent?

For a continuous outcome, the mean is an average of the measured values. In this trial, each value is a Stroop difference score: reaction time to cocaine-related words minus reaction time to neutral words. The registry describes the reported endpoint as the mean score over four time points. The sign has a task-specific interpretation: positive means slower responding to cocaine words and greater attentional bias; negative is described as no attentional bias to those words.

A mean can summarize the center of a group’s scores, but it does not show whether individual scores cluster closely or vary widely. It also does not by itself express a treatment contrast. To evaluate a buspirone-versus-placebo difference, readers would need the relevant group results and a clearly defined comparison across the challenge conditions. Those comparative results are not reported in the registry record.

What does the standard deviation describe?

Standard deviation describes the spread of individual observations around their mean. In general, a larger standard deviation indicates more variability among the measured values, while a smaller one indicates that values are more tightly grouped. It is not the same as a confidence interval: standard deviation describes variation in observations, whereas a confidence interval expresses uncertainty about an estimate under a statistical method. The record names standard deviation but does not report its values for the primary outcome.

For repeated or condition-specific measurements, the interpretation of dispersion depends on what observations are included. The endpoint description says the score averages four times and that each participant contributed one data point for each methylphenidate dose level. It does not give a detailed statistical model for accounting for the repeated measurements or describe how variability across times and doses was handled beyond the stated summary score.

Why do the multiple challenge conditions matter?

The registered challenge has four dose levels: 15mg, 30mg, 60mg, and 0mg. A comparison can be framed in different ways, such as considering a particular dose, comparing patterns across dose levels, or summarizing across conditions. These choices address different questions. The registry record does not identify one primary contrast or report the full set of dose-specific results. It explicitly indicates that the primary outcome has several categories or time points and is not reduced to one comparison.

General statistical practice distinguishes a prespecified primary contrast from exploratory comparisons. When many outcomes, doses, or time points are tested, the chance of finding at least one apparently notable result can rise if multiplicity is not addressed. Methods such as adjustment or a hierarchy of tests can be used, depending on the study plan. The registry record does not report whether any such approach was specified or applied. It would therefore be inappropriate to infer a multiplicity strategy from the design alone.

How should planning calculations be read?

The registry describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not results of an observed power calculation. Such illustrations estimate the number of participants per arm for a target power under the stated assumptions; they do not show the trial’s actual power and do not establish that the planned enrollment was sufficient.

The registry record does not report numerical planning estimates or the observed effect magnitude used for those illustrations. It also does not report the trial’s own sample-size justification. Because the primary outcome results are absent, the planning framework cannot be independently interpreted as a description of the achieved treatment contrast. A planning estimate is conditional on its assumptions and should not be treated as evidence that a result is statistically significant or clinically meaningful.

What can be concluded from the posted analysis information?

The record lists 0 analyses and does not report an analysis model, standard errors, confidence intervals, or test statistics for the primary outcome. In general, an analysis model defines how the outcome is related to treatment and other design features. For repeated measurements, a model may also describe within-participant dependence. The particular approach used in this trial is not reported in the registry record, so no model-specific assumptions can be assessed.

Likewise, a p-value, if available, would address compatibility with a specified statistical null model; it would not measure the size or practical importance of an effect. A confidence interval would help communicate precision, but neither is reported for the primary outcome. General explanations of these tools cannot replace trial estimates. Here, the statistical information supports interpretation of the endpoint definition and design, while the comparative efficacy result remains unreported.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is structured across multiple methylphenidate dose levels and several measurement times. The registry record states that the outcome has several categories or time points and is not reduced to one comparison. It does not report a single primary contrast, a hierarchy of comparisons, or an adjustment for multiple testing. The record also lists 15 secondary outcome measures. Whether those measures were tested jointly, separately, or under a prespecified multiplicity plan is not reported in the registry record.

As a general statistical concern, examining many outcomes, times, or dose conditions can increase the opportunity for chance findings if the analysis does not account for the number of comparisons. This does not establish that a false-positive result occurred in this trial; the record contains no such results. It means only that the interpretation of a set of comparisons depends partly on how the testing plan handled multiplicity, which is not described.

Missing-data methods are not reported in the registry record. The outcome description says each participant contributed one data point per dose level, but it does not state whether all randomized participants contributed complete measurements, how missing observations were handled, or whether imputation or other methods were used. The analysis population is also not reported: the record does not identify whether results would be based on all randomized participants, participants who completed treatment, or another defined group.

Randomization and masking are registered, but those design features do not identify the analysis population or resolve missing-outcome questions. Without participant flow, completeness information, and analysis methods, the risk that missing observations could affect the reported outcome cannot be assessed. The posted record also lists 0 analyses, leaving the detailed statistical handling of the primary and secondary outcomes unreported.

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 non-serious adverse event terms

The adverse-event record lists 20 participants at risk for serious adverse events in the Buspirone group and 20 in the Placebo group. It records 0 serious adverse events in each group. The record does not list any serious-event terms. The death counts are null, so deaths are not reported in the registry record; a null entry should not be read as a reported count of zero.

For other adverse events, the record lists 20 participants at risk in each group. It records 0 in the Buspirone group and 1 in the Placebo group. These entries are descriptive counts, not a statistical comparison. The registry does not provide event descriptions for the non-serious event, a measure of uncertainty, or a formal between-group safety analysis. It also does not report whether the event was considered related to a study intervention.

These figures should be interpreted in the context of the trial record, rather than as proof that an event cannot occur. The adverse-event groups list 20 at risk per arm, while the overall enrollment is 50; the record does not explain the relationship between those denominators. Serious-event counts and other-event counts describe the posted safety information only. They do not establish comparative safety beyond the observations recorded in this trial.

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

The record is useful for identifying what the trial set out to study: buspirone versus placebo in people with cocaine dependence, assessed during an acute methylphenidate challenge. Its primary measure was attentional bias on a Stroop task, defined as the reaction-time difference between cocaine-related and neutral words and summarized over four time points. The design is registered as randomized, triple-masked, and parallel.

The record does not report the primary outcome estimates. It therefore does not show whether scores differed between groups, whether any pattern varied by methylphenidate dose, or how precise an estimate might be. No treatment effect size, confidence interval, or primary-outcome test result is reported in the registry record. The completed status does not fill these gaps.

The endpoint is a task-based measure, not a direct measure of drug use or a clinical outcome. Even if a score difference were reported, its interpretation would depend on the comparison, uncertainty, and relationship to outcomes beyond the task. General knowledge about what the Stroop task measures cannot establish that a particular change would translate into a change in behavior outside the study.

The adverse-event entries show no serious adverse events recorded among the listed at-risk participants in either group and one other adverse event recorded in the placebo group. They do not provide a full account of comparative safety, event attribution, or uncertainty. The null death entries are not reported death counts.

Accordingly, the posted information supports conclusions about the trial’s registered structure, endpoint, and limited adverse-event counts. It does not support a conclusion that buspirone did or did not alter attentional bias, nor does it establish a treatment benefit or lack of benefit. Those conclusions require outcome estimates and their statistical context, which are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial illustrates why a registered outcome definition and a reported result are different kinds of information. The record explains how attentional bias was operationalized: as a reaction-time difference between cocaine-related and neutral words. That clarity helps define the intended measurement, but it does not reveal the group means, variability, or treatment contrast.

The design also raises a common statistical interpretation issue. The primary endpoint spans four time points and four challenge dose levels. A result can depend on whether the question concerns a specific dose, a pattern across doses, or a summary across conditions. Without a stated contrast and corresponding estimates, readers cannot determine which comparison answers the primary question or how results across conditions fit together.

Precision is as important as direction. A numerical estimate without uncertainty can be hard to evaluate, while a small or imprecise difference may be compatible with a range of underlying effects. This record does not report confidence intervals or other primary-outcome uncertainty measures, so the precision of the trial’s result cannot be evaluated.

The record also demonstrates that completion status and enrollment are not substitutes for transparent analysis reporting. Although the trial is marked completed and lists enrollment of 50, it lists 0 analyses and does not report the primary comparison. Registered secondary measures and limited adverse-event counts answer different questions; they do not reconstruct the missing efficacy analysis.

Statistically, the central lesson is to separate design, measurement, analysis, and inference. The registry describes the first two in some detail, gives only limited safety counts, and does not report the comparative primary outcome analysis. Keeping those distinctions clear prevents a study rationale or endpoint definition from being mistaken for evidence of an observed effect.

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.

A central limitation of the available record is the absence of comparative primary-outcome results. The endpoint is described, but group means, standard deviations, contrasts, and uncertainty estimates are not reported. This prevents evaluation of the direction, magnitude, and precision of any treatment difference.

The primary outcome has multiple doses and time points, yet a single comparison is not reported. The complete analysis strategy, including how repeated measurements were handled and which contrast was primary, is not reported in the registry record. The approach to multiplicity is also not reported, despite the registered secondary outcome measures and multiple challenge conditions.

The outcome description gives measurement timing and says each participant contributed a value at each dose level, but participant flow and outcome completeness are not described. Missing-data methods and the analysis population are not reported. It is therefore not possible to assess how many randomized participants contributed to each result or how incomplete data, if any, were handled.

The posted arm descriptions are incomplete. They identify buspirone or its placebo and methylphenidate or its placebo, but do not give the full dosing and administration sequence. The registry does not report the randomization method, allocation concealment, or which roles were masked. These omissions limit assessment of how the registered design was implemented.

Safety interpretation is also constrained. The adverse-event record gives at-risk counts and a small number of recorded events, but does not provide descriptions of the other adverse event, attribution, or a formal comparison. Death counts are null rather than reported as zero. Finally, the overall enrollment of 50 and the adverse-event denominators of 20 per group are not reconciled in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Psychopharmacology for Cocaine Dependence - Buspirone — NCT01267292.
• Registry record last updated 2017-05-04; status last verified 2017-05.
• Results first posted 2017-05-04.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes NCT01267292, a completed, randomized, triple-masked, parallel Phase 2 trial sponsored by The University of Texas Health Science Center, Houston. It lists enrollment of 50 and dates of 2011-03 for the start and 2015-12 for primary completion.

The study compared buspirone with placebo in a design that included an acute methylphenidate challenge. Its primary outcome was a Stroop-task attentional-bias score in milliseconds, defined by the difference in reaction times to cocaine-related and neutral words. The endpoint summary covered four time points and four methylphenidate dose levels.

The registry lists 15 secondary outcome measures and 0 analyses. It does not report comparative primary-outcome estimates or analysis details. For safety, it records 0 serious adverse events in each group, and other adverse-event counts of 0 for Buspirone and 1 for Placebo. Deaths are not reported in the registry record.