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 Nabilone in Cannabis Users With PTSD (NCT03251326), a randomized phase 1, phase 2 study. The primary outcome is Cue Reactivity (Emotional Stroop Task).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03251326 |
| Phase | Phase 1, Phase 2 |
| Condition | Cannabis, Post Traumatic Stress Disorder |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Double |
| Enrollment | 4 |
| Arms in the primary outcome | n/a |
| Lead sponsor | New York State Psychiatric Institute |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned cannabis users with post-traumatic stress disorder (PTSD). The registry lists cannabis use and PTSD as the conditions of interest. Four participants were enrolled, and the record says that two participants completed the study.
Intervention
The study included orally administered nabilone and smoked cannabis. The listed nabilone capsules were 4 mg, and the smoked cannabis conditions were 0.0 and 5.6% THC. Propranolol was also listed as an intervention, with capsules of 40mg.
Comparator
Placebo capsules were included. The registry lists groups with active or placebo nabilone, propranolol and cannabis conditions. The detailed protocol for how each condition was assigned and compared is not reported in the registry record.
Primary question
The primary outcome was cue reactivity measured with an Emotional Stroop Task over a timeframe of 1 month. The study description identifies an interest in the effects of smoked cannabis and oral nabilone on multiple dimensions of PTSD symptomatology. The record does not provide an outcome estimate or describe the task’s scoring in enough detail to identify the exact treatment contrast.
In broad terms, the clinical research question was whether responses to trauma-related cues differed across drug and placebo conditions among cannabis users with PTSD. The crossover model indicates that the study was intended to make within-participant comparisons, rather than relying only on comparisons between separate treatment groups. However, the available record does not establish which specific condition contrasts were the principal comparisons, how the study sequence was organized, or how cue reactivity was quantified. Those details are not reported in the registry record. Because the outcome data could not be located, the clinical question remains unanswered by the posted results.
3. Trial Design
The registry describes a randomized, double-masked, crossover study in Phase 1 and Phase 2. It lists an enrollment of 4 and a status of terminated. The record gives the study start as 2015-10 and primary completion as 2019-06. It identifies cannabis users with PTSD as the population and cue reactivity on an Emotional Stroop Task as the primary outcome, with a timeframe of 1 month.
The intervention list includes nabilone, cannabis, propranolol and placebo. The arm descriptions specify nabilone capsules (4 mg), propranolol capsules (40mg), smoked cannabis at 0.0 and 5.6% THC, and placebo capsules. Group labels combine active and placebo conditions, but the registry does not give enough detail to reconstruct the full sequence or all intended comparisons. The precise allocation schedule, treatment-period lengths, washout procedures and masking procedures are not reported in the registry record.
In a crossover study, participants receive more than one study condition, so comparisons can use each participant as their own reference. In general, this design can reduce the influence of stable differences between participants. It also requires careful consideration of treatment order, period effects and any carryover from one condition to another. The registry does not report how these issues were addressed in this study.
The record says that the study was terminated due to lack of feasibility. It further reports that staff responsible for data collection, organization and cleaning had left the institution, and that efforts to locate the data from the two participants who completed the study were unsuccessful. Thus, although the design and intended outcome are described, the results needed to assess the study question are not available.
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: The study was terminated and the PI and the study team left the institution; as such, no outcome data is available.
Overall Study
| Stage | Active Nab > Plac Prop > Plac Cann | Plac Nab > Act Prop > Plac Cann | Plac Nab > Plac Prop > Act Cann | Plac Nab > Plac Prop > Plac Cann |
|---|---|---|---|---|
| STARTED | 1 | 1 | 1 | 1 |
| COMPLETED | 1 | 1 | 0 | 0 |
| NOT COMPLETED | 0 | 0 | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: We cannot provide data as the study was terminated due to lack of feasibility. The staff responsible for data collection, organization, and cleaning have left the institution; we have made every effort to locate the data for the two participants who completed the study, but have been unsuccessful. We do not have access to the data.
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 | Nabilone/Propranolol/Placebo + Smoked Cannabis/Placebo Placebo |
|---|---|---|
| Participants analysed | 2 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 2 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 2 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Cue Reactivity (Emotional Stroop Task), measured over 1 month.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was cue reactivity measured with an Emotional Stroop Task. The registry’s timeframe for this outcome is 1 month. Cue reactivity refers broadly to responses evoked by cues associated with a particular experience or context; in this study, the stated focus was trauma-related cue reactivity among cannabis users with PTSD.
As a general matter, an Emotional Stroop Task is used to examine whether emotional content affects a person’s response to a task. Such measures can offer a way to study attentional or response patterns under different cue conditions. The registry record does not report the task instructions, the specific score used, the measurement unit, or the direction that would indicate greater or lesser reactivity. Those details matter because the interpretation of a score depends on how it is defined and calculated.
The endpoint could have been used to compare responses across the study’s drug and placebo conditions, consistent with the stated interest in the effects of smoked cannabis and oral nabilone on PTSD symptomatology. But the registry reports that the outcome data could not be provided. It therefore supplies no endpoint values, treatment contrasts, uncertainty estimates or analysis results. The endpoint’s intended role can be described, but its observed behavior and any differences between conditions cannot be assessed from the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that no primary outcome data are available. The registry states that the study was terminated due to lack of feasibility and that the data for the two participants who completed the study could not be located despite efforts to find them. Consequently, there is no reported estimate of cue reactivity under any condition and no reported comparison between nabilone, smoked cannabis, propranolol or placebo.
The enrollment was 4. That number describes the participants enrolled, not the number contributing analyzable primary outcome data. The record says that two participants completed the study, but it also says that their data were unavailable. Completion alone does not establish that complete, usable measurements were collected for every condition or that a valid analysis could be conducted. In this case, the registry explicitly reports that the data could not be accessed.
No effect estimate, standard error, confidence interval or hypothesis test is reported for the primary outcome. A confidence interval generally expresses the range of values compatible with an estimate under a statistical model, while a hypothesis test evaluates how compatible the observed data are with a specified null hypothesis. These tools require analyzable data and a defined comparison. Since neither is reported, the precision of any treatment contrast cannot be evaluated. There is also no basis for describing the direction or size of an effect.
The registry lists zero affected participants and zero deaths in each of its displayed adverse-event groups. These entries describe the recorded adverse-event counts in those groups; they do not restore the missing primary outcome information or establish what was observed in the unavailable study data. The record does not give further context that would allow a broader safety interpretation.
The crossover design could, in principle, support within-participant comparisons. But the design label is not a substitute for outcome data, and no analysis results are listed. The intended advantage of comparing a participant across conditions cannot be evaluated without the measurements and details of treatment order, period handling and analysis. The registry record does not report those details.
Accordingly, the posted results do not establish whether cue reactivity differed across conditions, how large any difference might have been, or how precisely it could be estimated. They also do not establish equivalence or absence of an effect. The appropriate statistical interpretation is that the primary question is unresolved in the available record, rather than answered in either direction.
9. Statistical Methods Explained
What does a randomized crossover design mean?
Randomization assigns study conditions according to a chance-based process, which is intended to reduce systematic allocation differences. In a crossover design, participants receive multiple conditions, allowing comparisons within the same person. In general, a within-person comparison can account for participant characteristics that remain relatively stable over the study. It does not eliminate every source of bias: treatment order, changes over time, carryover and missing measurements can still affect interpretation.
The registry identifies the study as randomized, double-masked and crossover. It does not report the randomization sequence, the method used to preserve masking, the number or duration of treatment periods, washout intervals, or how potential period and carryover effects were handled. These are important design details, but they cannot be inferred from the design labels alone.
What can be learned from the primary outcome entry?
The primary outcome is named as cue reactivity on an Emotional Stroop Task, with a timeframe of 1 month. An endpoint definition normally identifies what is measured, how it is scored, when it is measured and which contrast is intended for analysis. Here, the registry does not provide the measurement unit, a statistical parameter, a dispersion measure or a detailed scoring definition. It also does not report an outcome estimate. As a result, the entry identifies the general outcome topic but not the numerical quantity that would be needed for statistical interpretation.
Why is an estimate needed?
A treatment comparison is usually represented by an effect estimate, such as a difference in outcome between conditions, accompanied by a measure of uncertainty. The estimate describes the observed contrast; an uncertainty measure indicates how much information the data provide about that contrast. A confidence interval is one common way to communicate uncertainty. It is not available for this outcome because no results are reported.
A p-value, when reported, describes the compatibility of the data with a specified null model under the assumptions of a statistical test. It does not measure the size or clinical importance of an effect. No p-value or other test result is listed for the primary outcome. In the absence of an estimate and its uncertainty, statistical significance cannot be assessed, and neither the direction nor the precision of any contrast can be described.
What is the role of the sample size?
The registry reports an enrollment of 4 and identifies two participants who completed the study. Sample size affects how much information is available, but it does not by itself determine whether an estimate is unbiased or whether a study can answer its question. A small dataset will generally offer limited precision, especially when comparisons involve multiple conditions, but the outcome data are unavailable in this record, so no precision calculation can be grounded in observed results.
The record does not report a sample-size justification, target effect, or statistical power plan. Those design choices are not reported in the registry record. A planning calculation based on an effect estimate is not an observed treatment result, and no observed primary outcome effect is available to interpret. There is therefore no basis for presenting a power claim for the completed study.
Why do crossover studies need period and carryover considerations?
General statistical practice for crossover studies considers whether responses change across periods for reasons unrelated to the treatment, and whether an earlier condition could affect responses during a later condition. Analysis may also need to account for the pairing of observations within a participant. The registry record does not describe the planned or performed statistical treatment of these issues. Without sequence, period and outcome data, it is not possible to determine whether such effects occurred or how they influenced the intended comparisons.
What do the missing results imply for analysis?
The registry says that data for the two participants who completed the study could not be located. Without access to those records, an analyst cannot verify measurements, apply a scoring rule, check data quality, fit a model or reproduce a treatment comparison. The registry lists no analysis results. It does not describe an analysis population, a method for handling missing outcome values, a model specification, covariate adjustment or sensitivity analysis. These aspects of the statistical plan and execution are not reported in the registry record.
Overall, the design labels provide a broad description of how the study was organized, and the endpoint name indicates what it sought to measure. They do not supply the numerical evidence required to estimate a treatment effect. General statistical principles can explain what an analysis would usually need, but they cannot replace the missing measurements or establish what this study found.
10. Multiplicity, Missing Data and Analysis Populations
The study description refers to multiple dimensions of PTSD symptomatology, and the intervention list includes nabilone, smoked cannabis, propranolol and placebo. This creates the possibility of multiple outcomes or comparisons, but the registry record does not describe a statistical plan for controlling multiplicity. In general, when many hypotheses are tested, the chance of finding an apparently notable result by chance can increase. Approaches to multiplicity depend on which comparisons are confirmatory and how they are related; no such approach is reported.
The primary outcome is identified as cue reactivity on an Emotional Stroop Task, but the record does not provide a detailed analysis specification or results. It does not report planned contrasts, a hierarchy of outcomes, an adjustment method, interim analyses or stopping rules. These details are not reported in the registry record, and should not be inferred from the randomized, double-masked crossover design.
Missing data are a central limitation. The record states that the study was terminated for lack of feasibility and that data for the two participants who completed the study could not be located. It does not describe whether measurements were missing at particular visits or conditions, whether any partial records existed, or how missing values would have been handled in an analysis. Because the underlying data were unavailable, no assessment of the pattern or consequences of missingness is possible.
The analysis populations are also not described. The record does not say which participants would have been included in an intended primary analysis or how completion and adherence would have affected inclusion. Enrollment and completion counts alone do not define an analysis population. Without a documented population, analysis method and accessible outcome data, the impact of missingness and the robustness of any result cannot be evaluated.
11. What the Result Does, and Does Not, Mean
The record documents a study designed to examine cue reactivity in cannabis users with PTSD across drug and placebo conditions. It also documents that the trial was terminated due to lack of feasibility and that primary outcome data were unavailable. Those are the main conclusions that can be drawn from the posted information.
The record does not show that nabilone, smoked cannabis, propranolol or placebo changed cue reactivity. It does not show that the conditions had similar effects, and it does not provide evidence that any effect was absent. These distinctions matter: an unavailable result is not a null result. A null result would require an analysis of data that did not show a detectable difference under a specified method; that analysis is not reported.
The design alone cannot answer the clinical question. Randomization and masking describe intended protections against certain biases, and crossover assignment can support within-participant comparisons. But those features do not establish that a treatment effect occurred, nor do they indicate its magnitude or precision. The missing outcome data prevent those questions from being examined.
The enrollment and completion information should also be interpreted narrowly. Four participants were enrolled, and two completed the study, according to the record. The data from the two completers could not be located. These counts describe study progress, not an estimate of treatment effect or a measure of how well the intervention performed.
Likewise, the adverse-event entries list zero affected participants and zero deaths in each displayed group, but those entries do not provide an outcome analysis and do not resolve the missing-data problem. The available record supports a description of study design, status and data availability; it does not support a conclusion about whether the interventions altered PTSD-related cue reactivity.
12. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between a study’s intended design and the evidence available for analysis. Randomization, masking and a crossover structure can be important design features, but they do not produce interpretable estimates in the absence of accessible outcome data. The record shows why reporting study progress and data availability is necessary context for evaluating a clinical question.
The study also illustrates how a within-participant design depends on complete and traceable measurements. In general, crossover comparisons can use each person as their own reference, but this benefit relies on having outcomes across the relevant conditions and a suitable account of treatment sequence and time. The registry identifies a crossover model, yet the unavailable data prevent assessment of whether the planned comparisons were completed or whether design-related issues were addressed.
Its small enrollment and the reported completion count further emphasize the difference between participant flow and an effect estimate. Counts can describe recruitment and completion, but they cannot substitute for outcome values, uncertainty estimates or an analysis plan. Without those elements, statistical precision and the direction of a comparison remain unknown.
Finally, the record highlights that an unavailable result is not evidence for or against a treatment effect. Clear descriptions of missing data, analysis populations and statistical methods help readers understand what a study can establish. In this case, the most defensible statistical conclusion is that the intended question remains unanswered in the registry record.
13. 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 most consequential limitation is the absence of primary outcome data. The registry says the study was terminated due to lack of feasibility and that staff responsible for data collection, organization and cleaning had left the institution. Despite efforts to locate the records for the two participants who completed the study, the data could not be found. No numerical result for cue reactivity is available.
The record gives limited detail about the planned or completed comparisons. Although it identifies randomization, double masking and a crossover model, it does not report the treatment sequence, the duration of individual periods, washout procedures or handling of period and carryover effects. It also does not describe how the Emotional Stroop Task was scored, the unit of measurement, the statistical model or any adjustment for multiple comparisons.
The enrollment was 4, and two participants are described as having completed the study. With the underlying measurements unavailable, it is not possible to determine whether those participants had data for every condition or whether any observations were incomplete. The registry does not report an analysis population, missing-data method, sample-size justification or planned precision target.
The listed adverse-event groups show zero affected participants and zero deaths, but the record does not provide additional context for interpreting those entries. These limitations mean that the registry can describe the study’s broad design and its failure to yield accessible outcome data, but it cannot support an estimate of cue reactivity or a comparison of the study conditions.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Nabilone in Cannabis Users With PTSD — NCT03251326.
- Registry record last updated 2022-07-15; status last verified 2022-06.
- Results first posted 2020-10-12.
- 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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17. Record Summary
The registry describes NCT03251326, titled “Nabilone in Cannabis Users With PTSD,” as a randomized, double-masked crossover study in Phase 1 and Phase 2. The sponsor is New York State Psychiatric Institute. The study enrolled 4 participants, began in 2015-10, had primary completion in 2019-06, and is listed as terminated.
The interventions include nabilone, smoked cannabis, propranolol and placebo. The primary outcome is cue reactivity measured with an Emotional Stroop Task over a timeframe of 1 month. The record states that the study was terminated due to lack of feasibility and that data for the two participants who completed the study could not be located. No primary outcome analysis is reported, so the effect of the study conditions on cue reactivity cannot be assessed from the registry record.