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 Buspirone Treatment for Marijuana Dependence (NCT00875836), a randomized phase 4 study. The primary outcome is Percent Marijuana-negative Urine Drug Screens (UDS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00875836 |
| Phase | Phase 4 |
| Condition | Marijuana Dependence |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 175 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Medical University of South Carolina |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned adults with marijuana dependence. The registry lists Marijuana Dependence as the condition and describes the intended population as marijuana-dependent adults. The enrollment was 175. The registry record does not report further eligibility details in the information available for this analysis, such as how dependence was defined or which clinical characteristics were required.
Intervention
The intervention was buspirone. The study summary describes buspirone as being combined with motivational enhancement therapy (MET) and contingency management (CM), which were incorporated to encourage engagement and retention. The registry does not report the buspirone dose or provide further details about how MET and CM were delivered.
Comparator
The comparator was placebo. The study summary also describes placebo as combined with MET and CM. The posted arm descriptions identify Buspirone and Placebo, while the registry record does not provide further details about placebo procedures or the delivery of the accompanying behavioral interventions.
Primary question
The primary question was whether the buspirone group had a different percentage of marijuana-negative urine drug screens from the placebo group during the period of weekly urine sampling. The registry’s stated hypothesis was that buspirone with MET and CM would reduce the percentage of marijuana-positive screens compared with placebo with MET and CM. The posted outcome is expressed as the percentage of negative screens, so it describes the same urine-test outcome from the negative-result perspective. The registry record does not report an inferential comparison for this endpoint.
3. Trial Design
This was a randomized, triple-masked, parallel-group, phase 4 study. The registry lists an enrollment of 175 and describes the intervention arms as Buspirone and Placebo. The sponsor was the Medical University of South Carolina. The study began in 2009-09, had primary completion in 2014-06, and is listed as completed. These registry entries describe the planned and recorded study framework; they do not by themselves establish how participants were randomized, what masking procedures were used, or whether the planned procedures were followed in every case.
The study summary says that motivational enhancement therapy (MET) and contingency management (CM) were incorporated to encourage study engagement and retention. The stated comparison was therefore buspirone versus placebo in the context of those interventions, rather than a comparison of medication alone against no treatment. The registry record does not report how MET or CM was standardized, how often participants received them, or whether adherence to either intervention was measured.
The primary outcome was the percentage of marijuana-negative urine drug screens. Participants provided a urine sample once weekly for twelve weeks, and the percentage of negative samples was calculated per group. Retention in the Study and Marijuana Craving are listed as secondary outcomes. The record does not report the details of allocation concealment, the identities of masked parties, medication dose, or the precise analysis population. Those details should not be inferred from the general design labels.
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
| Stage | Buspirone | Placebo |
|---|---|---|
| STARTED | 88 | 87 |
| COMPLETED | 45 | 47 |
| NOT COMPLETED | 43 | 40 |
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 | Buspirone | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 88 | 87 | 175 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 88 | 87 | 175 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 21 | 20 | 41 |
| Sex: Female, Male: Male | Participants | 67 | 67 | 134 |
| Region of Enrollment: United States | participants | 88 | 87 | 175 |
6. Primary Endpoint
The registry lists the primary outcome as Percent Marijuana-negative Urine Drug Screens (UDS), measured over Participants provided a once-weekly urine sample for twelve weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of UDS |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of urine drug screens that were negative for marijuana. According to the registry description, participants submitted a urine sample weekly, with sampling over twelve weeks, and the percentage of negative samples was calculated per group. A urine test provides an objective measurement of whether marijuana was detected in the submitted sample. Expressing the endpoint as a percentage describes how often negative results occurred across the samples represented in the group calculation.
This endpoint was used to assess marijuana use during the trial, consistent with the study’s stated aim of evaluating buspirone for reducing use among adults with marijuana dependence. A higher percentage of negative screens would indicate that a greater share of the samples included in the calculation were negative; it does not, by itself, describe an individual participant’s full pattern of use or establish why a result was negative.
The posted group values are 7.2 for Buspirone and 6.4 for Placebo, with the endpoint unit identified as percentage of UDS. The registry record does not report a measure of spread or confidence limits for these values. It also does not report a posted inferential comparison for this count-type endpoint, so the group values alone do not establish the precision or statistical significance of a difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry reports a primary outcome value of 7.2 for Buspirone and 6.4 for Placebo, with the outcome described as the percentage of marijuana-negative urine drug screens. These values are descriptive group results. They do not, on their own, indicate how uncertain the comparison is, whether the difference is compatible with chance variation, or whether an adjusted analysis would give the same conclusion.
The posted record does not include a confidence interval, standard error, or p-value for this primary comparison. It also reports no posted analyses. The registry’s endpoint classification notes that values are missing or not estimable for a two-arm comparison for this count-other endpoint. Thus, the presence of group values should not be mistaken for a reported treatment-effect estimate with an uncertainty interval. The record does not provide an inferential result that can support a claim of statistical significance or a precise estimate of the between-group effect.
The arm entries list 88 for Buspirone and 87 for Placebo. These are the arm-level counts recorded alongside the endpoint, not proof that every participant contributed the same number of urine samples or that all scheduled samples were available. The endpoint description refers to weekly samples, but the registry record does not report the number of samples actually collected, the completeness of follow-up, or how missing urine tests were handled. Those omissions matter because a percentage based on available samples may be affected by the amount and pattern of missing data.
The posted outcome is also limited to the measurement described: urine-screen results during the study’s sampling period. It does not by itself answer whether participants reduced use outside those sampling times, whether any observed outcome persisted after the trial, or whether other clinical outcomes changed. Retention and Marijuana Craving are listed as secondary outcomes, but the record does not post results for them in the information analyzed.
These results should therefore be read as group-level descriptive values in a completed randomized trial, not as a definitive estimate of treatment effect. The registry record does not report a sponsor analysis for the primary comparison, and the absence of an inferential result is not evidence that the groups were equivalent. Nor is it evidence that one treatment was superior. A sound interpretation requires the missing analysis details, including uncertainty estimates and the handling of incomplete outcome data, none of which is reported in the registry record.
9. Statistical Methods Explained
What does the endpoint represent?
The primary measure is a group-level percentage of marijuana-negative urine drug screens. A percentage condenses the pattern of test results into a summary, making the outcome easier to compare across groups than a list of individual samples. That summary remains dependent on the samples that entered its calculation. The registry states that participants provided samples once weekly for twelve weeks and that percentages were calculated per group, but it does not report the number of submitted samples or the exact calculation procedure.
As a general statistical point, repeated measurements from the same participant are not automatically independent observations. Results from samples belonging to one person can be related to each other. An analysis that treats every sample as independent may understate uncertainty if it does not account for that within-participant relationship. The registry record does not report whether the primary analysis used participant-level summaries, a repeated-measures model, or another approach.
What does a group value tell us?
A group value describes the observed endpoint according to the calculation used. The posted values are 7.2 for Buspirone and 6.4 for Placebo. Without a measure of spread or an uncertainty interval, the reader cannot judge from those values alone how variable the participant-level or sample-level results were. A group summary also does not show whether the pattern was similar across participants or driven by a smaller subset with more available samples.
As a general statistical point, a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. It helps distinguish a relatively precise estimate from one compatible with a broader range of possible effects. No confidence interval is reported for this primary comparison in the registry record. The record also does not report a standard error or p-value for the endpoint.
Why is a direct comparison important?
A treatment question concerns the contrast between the randomized groups, not simply whether either group has a particular value. An inferential comparison estimates that contrast and quantifies its uncertainty. The registry record’s endpoint classification says that values are missing or not estimable for a two-arm comparison for this count-other endpoint. No recalculated comparison is presented. The discrepancy flag is false, so there is no reported disagreement between a sponsor analysis and a recalculation; however, there is also no sponsor inferential analysis posted for this endpoint in the registry information.
As a general statistical point, a valid comparison depends on the outcome’s scale and the way observations were collected. A percentage based on repeated urine samples may require methods that account for both the bounded nature of percentages and dependence among samples from the same participant. If the group summaries are based on different amounts of observed data, the comparison may also depend on how missing observations were treated. The record does not identify the model, estimand, or assumptions used for an inferential analysis.
How should the planning illustrations be read?
Planning calculations based on an observed effect are not a report of the trial’s power as conducted. In general, such calculations illustrate the sample size that might be required under stated assumptions to detect a chosen fraction of an observed effect. The registry’s planning assumptions specify a two-sided significance level of 0.05, equal allocation, and a normal approximation. They describe the effect to detect as a stated fraction of the observed effect. No numerical planning results are stated in the registry information analyzed here, and the illustrations are not evidence that the original trial was designed around those assumptions.
As a general statistical point, observed-effect planning can be unstable because an effect estimated from a study may be imprecise. Planning values should therefore be interpreted as conditional illustrations rather than guarantees. They are not observed power, do not establish the probability that the study’s result is correct, and cannot replace the trial’s actual design rationale. The registry record does not report a sample-size justification, and no such rationale should be inferred from planning assumptions stated for an illustration.
What can be concluded from the posted methods information?
The record identifies the design as randomized, triple-masked, and parallel, and it gives arm-level outcome values. It does not report the allocation method, analysis model, handling of repeated observations, missing-data method, or inferential output for the primary endpoint. These gaps limit reproducibility and make it difficult to assess the assumptions behind any treatment-effect interpretation. General statistical principles can explain why those details matter, but they cannot fill in methods that the registry record does not report.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists Retention in the Study and Marijuana Craving as secondary outcomes, in addition to the primary urine-screen endpoint. The record does not report a multiplicity procedure, such as a method for controlling the chance of false-positive findings across multiple outcomes. It also does not report a hierarchy or other decision rule for interpreting primary and secondary outcomes together. Without those details, the secondary outcomes should not be treated as confirmatory evidence, and no adjustment should be assumed.
The registry describes weekly urine sampling over twelve weeks, but does not report how many samples were received, whether any were missed, or how missing samples were handled. It does not say whether missingness was treated as positive, excluded from the percentage, imputed, or addressed with a model. Each approach entails assumptions that can affect the endpoint. The record also does not explain whether participants who discontinued contributed available samples to the primary calculation.
The analysis population is not reported in the registry record. Although the trial is described as randomized and arm counts are posted, the record does not specify whether the primary analysis included all randomized participants, only participants with an available urine sample, or another population. It does not report a protocol-adherent analysis or a rule for retaining participants in their assigned groups.
These omissions prevent a full assessment of attrition, missing-data bias, and the relationship between the planned and analyzed populations. They also mean that the posted arm values cannot be assumed to represent a particular analysis population. The registry record reports no posted analyses for the outcome, so it does not resolve these uncertainties.
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 |
|---|---|---|---|
| Buspirone | 0 | 88 | 0.0% |
| Placebo | 0 | 87 | 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 |
|---|---|
| Buspirone | 73 of 88 |
| Placebo | 66 of 87 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Buspirone | Placebo |
|---|---|---|---|
| Other | General disorders | 43 of 88 | 40 of 87 |
| Gastrointestinal | Gastrointestinal disorders | 36 of 88 | 23 of 87 |
| Headache | Nervous system disorders | 28 of 88 | 27 of 87 |
| Dizziness or lightheaded | Nervous system disorders | 36 of 88 | 11 of 87 |
| Congestion | Respiratory, thoracic and mediastinal disorders | 19 of 88 | 18 of 87 |
| Musculoskeletal | Musculoskeletal and connective tissue disorders | 11 of 88 | 24 of 87 |
| Drowsiness | Nervous system disorders | 17 of 88 | 15 of 87 |
| Insomnia | Nervous system disorders | 16 of 88 | 15 of 87 |
| Sinus/allergies/flu | General disorders | 13 of 88 | 12 of 87 |
| Anxiety or Depression | Psychiatric disorders | 4 of 88 | 5 of 87 |
The registry lists 0 serious adverse events among 88 at risk in the Buspirone group and 0 among 87 at risk in the Placebo group. These are the serious-event figures recorded for the two groups. They should be read as counts within the listed at-risk populations, not as proof that no safety events of any kind occurred.
The same record lists other adverse events affecting 73 of 88 at risk in the Buspirone group and 66 of 87 at risk in the Placebo group. These are separate entries from the serious adverse-event counts. The registry does not provide event terms for the other adverse events in the information, so their types, severity, timing, and relationship to treatment cannot be assessed from these counts alone. No serious adverse-event terms are listed.
Death counts are not reported in the registry record. The record also does not provide definitions, exposure-adjusted rates, or a detailed account of how adverse events were collected. The safety figures therefore describe what was recorded in these fields; they do not establish comparative safety or explain the clinical importance of the events.
12. What the Result Does, and Does Not, Mean
The posted primary outcome values describe the percentage of marijuana-negative urine drug screens in the Buspirone and Placebo groups during weekly sampling. The registry reports 7.2 for Buspirone and 6.4 for Placebo. These are descriptive values, not a complete estimate of a treatment effect: the record does not include an inferential comparison or uncertainty interval for this endpoint.
The result does not establish that buspirone reduced marijuana use, nor does it establish that buspirone had no effect. Without an analysis of the group contrast and its uncertainty, the direction and precision of the treatment effect cannot be assessed adequately. The values alone cannot show whether any difference is compatible with sampling variation or whether it would be meaningful beyond the measured urine-screen outcome.
The outcome is tied to urine samples collected during the study period. It does not directly report use outside the sampling schedule, longer-term outcomes, or the reasons for positive or negative tests. The registry record does not report how missing samples were handled, which limits interpretation of a group percentage when the completeness of sampling is unknown.
The trial design and the posted outcome should also be kept in context: the study summary describes MET and CM as accompanying both medication conditions. The primary question is therefore a comparison of buspirone and placebo within that context. The record does not provide enough detail to separate the contribution of medication from the contribution of the behavioral interventions, and it does not post results for the listed secondary outcomes.
In short, the registry supplies descriptive group outcome values and safety counts, but not the analysis needed to quantify a treatment comparison. Neither a conclusion of benefit nor a conclusion of no effect follows from the reported values alone.
13. Why This Trial Matters Statistically
This trial illustrates an important distinction between reporting group summaries and reporting a comparative treatment effect. A randomized design is intended to support comparison between assigned groups, but group values alone do not show the uncertainty around that comparison. For the primary urine-screen endpoint, the registry lists values for both groups but does not report an inferential result or precision measure. Readers therefore cannot determine from the posted record how strongly the data distinguish a group contrast from random variation.
The endpoint also highlights the challenges of repeated measurements. Weekly urine samples provide observations across the trial period, but samples from one participant may be related. The number and pattern of available samples may differ across participants. Statistical interpretation depends on how those dependencies and any missing samples are handled; the registry record does not report those methods.
Another statistical lesson is that study-design labels do not replace analysis details. Randomization, masking, and a parallel model describe important features of the trial, but they do not identify the analysis population, missing-data strategy, or model used for the primary outcome. Those details are needed to assess whether the analysis matches the clinical question.
Finally, descriptive safety counts should be kept distinct from a comparative safety assessment. Serious-event counts are reported as zero in both groups, while other adverse-event counts are also listed. Without event descriptions, follow-up detail, or an analysis plan, those entries have limited interpretive scope. This record demonstrates why a transparent report should pair outcomes with definitions, analysis methods, uncertainty estimates, and completeness information.
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.
Several trial-specific details needed to interpret the outcome are not reported in the registry record. The endpoint description gives the weekly sampling schedule and the group-level calculation, but does not state how many urine samples were collected or how many were missing. It does not explain how missed visits, unsubmitted samples, or discontinuation affected the percentage. This prevents assessment of whether the posted values represent comparable amounts of observation in the two groups.
The registry record does not report the primary analysis method, analysis population, or an inferential comparison for the endpoint. It gives no uncertainty interval or measure of spread for the posted group values. The endpoint classification indicates that a two-arm comparison was not estimable or was missing for this count-other outcome. Consequently, the record cannot support a precise estimate of the treatment contrast.
The record also lacks details about the medication dose and the implementation of MET and CM. Although the summary states that both were incorporated, the extent and consistency of their delivery are not described. Eligibility criteria and additional participant characteristics are not reported in the information analyzed here, limiting assessment of how broadly the findings might apply.
Multiplicity methods for the listed secondary outcomes are not reported. The record does not provide results for Retention in the Study or Marijuana Craving in the information. Safety reporting is also limited: serious-event counts and other adverse-event counts are listed, but event descriptions and death counts are not reported in the registry record. These gaps constrain conclusions about outcome interpretation, reproducibility, and safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Buspirone Treatment for Marijuana Dependence — NCT00875836.
- Registry record last updated 2016-08-10; status last verified 2016-07.
- Results first posted 2016-03-09.
- 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
NCT00875836 is a completed, randomized, triple-masked, parallel-group, phase 4 trial sponsored by the Medical University of South Carolina. The registry lists an enrollment of 175, a start date of 2009-09, and primary completion in 2014-06. The study compared Buspirone with Placebo in adults described as having marijuana dependence; the study summary says MET and CM were incorporated with both conditions.
The primary outcome was the percentage of marijuana-negative urine drug screens based on weekly samples over twelve weeks. The posted group values are 7.2 for Buspirone and 6.4 for Placebo. The registry record does not report an inferential comparison, uncertainty interval, analysis population, or missing-data method for this outcome. Retention in the Study and Marijuana Craving are listed as secondary outcomes, with no results reported in the information analyzed.
The serious adverse-event counts are 0 in each group; other adverse-event counts are also listed. Death counts are not reported in the registry record.