Cannabinoid Medication for Adults With OCD: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cannabinoid Medication for Adults With OCD (NCT02911324), a randomized phase 1, phase 2 study. The primary outcome is Change in Yale-Brown Obsessive Compulsive Scale.

2. Clinical Question

The study is registered as a randomized, parallel-group trial with no masking. Its brief summary describes the purpose as testing nabilone alone or in combination with EX/RP in adults with OCD. Since nabilone is included in both arms, this design does not directly compare nabilone with an untreated or placebo group. The comparison is about the addition of therapy within a nabilone regimen.

The registry identifies change in YBOCS as the primary outcome, measured at baseline (Week 0) and Week 4. It also lists feasibility of recruitment as a secondary outcome. Although the registry record gives an enrollment of 16, it does not report a primary-outcome estimate, uncertainty interval, or test of the between-group difference. Consequently, the clinical question is clear from the design, but the posted record does not provide the result needed to answer it.

3. Trial Design

The registry record describes NCT02911324, titled “Cannabinoid Medication for Adults With OCD.” It lists New York State Psychiatric Institute as the sponsor and gives the condition as obsessive-compulsive disorder. The study is marked completed, with a start date of 2016-09 and a primary completion date of 2019-01. Its listed enrollment is 16.

The trial is classified as Phase 1 and Phase 2, randomized, unmasked, and parallel-group. The two arm descriptions are nabilone alone and nabilone with EX/RP. Nabilone is described as 1 mg daily (BID) over 4 weeks in the nabilone arm. In the combination arm, the same nabilone regimen is paired with therapist-guided EX/RP during 4 weeks. No masking is listed; which roles, if any, were kept unaware of assignment is not reported in the registry record.

The primary outcome is change in YBOCS score, with measurements at baseline (Week 0) and Week 4. The registry defines the change as the baseline score minus the Week 4 score. Feasibility of recruitment is listed as a secondary outcome. The record notes two outcome measures, but does not report an analysis for the primary outcome. It also does not describe the recruitment-feasibility result in the information recorded for this trial.

The brief summary calls the study a pilot and explains that nabilone is a synthetic cannabinoid. It says the medication is approved by the FDA for chemotherapy-induced nausea and vomiting, but not for treating OCD. That background describes the study context; it is not a trial finding. The registry record does not report a detailed protocol, a justification for the enrollment target, or further information about how participants were recruited, assigned, or followed.

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.

Population: One participant in the nabilone+EX/RP group completed the study, but was not included in the final analysis due to inconsistent self-reporting of symptoms.

6. Primary Endpoint

The registry lists the primary outcome as Change in Yale-Brown Obsessive Compulsive Scale, measured over Baseline (Week 0) and Week 4.

The primary endpoint is change in the Yale-Brown Obsessive Compulsive Scale (YBOCS) score between baseline (Week 0) and Week 4. The scale ranges from 0 to 40, and the registry states that higher scores indicate more severe symptoms. It defines change by subtracting the Week 4 score from the baseline score. Under that definition, a positive change corresponds to a lower score at Week 4 than at baseline; a negative change corresponds to a higher score.

In general, a symptom scale can provide a structured way to describe severity and compare measurements over time. A change measure focuses on the difference between the two specified assessments rather than either score alone. For a randomized comparison, the relevant question is whether the change differs between assigned groups, not merely whether either group changes over time.

The registry names the measure and its time points but does not report group means, variability, a between-group estimate, or a confidence interval for this endpoint. It also does not explain who completed or rated the scale, or how scores were handled if an assessment was missing. Therefore, the endpoint is defined, but its observed result and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a randomized, parallel-group design and a continuous primary measure summarized by a mean and standard deviation. It does not report the statistical model or method used to compare groups. The explanations below describe general statistical concepts; they do not assert that any particular method was used in this trial.

What does randomization contribute?

In general, random assignment is used to reduce systematic differences between groups at the start of a study. It supports a causal interpretation of a contrast between assigned interventions when the trial is conducted and analyzed appropriately. Randomization does not guarantee that groups will be identical, especially in a small study, and it does not replace reporting baseline information, follow-up, outcomes, and analysis methods. The registry record does not describe the randomization sequence, allocation concealment, or implementation details.

What does a mean and standard deviation describe?

For a continuous measure, the mean describes the average observed value in a group. The standard deviation describes how spread out individual measurements are around that group mean. These summaries answer different questions: the mean describes location, while the standard deviation describes variability among measurements. Neither alone gives the uncertainty in a between-group estimate. A confidence interval around an estimate is used, in general, to show a range of values compatible with the data and the analysis assumptions. No such interval is reported for the primary outcome in this record.

Why distinguish change from a group contrast?

The specified endpoint is a change score: baseline YBOCS minus Week 4 YBOCS. A change score can describe movement over time for each group. To assess the randomized question, an analysis must compare the change between groups, or use another prespecified approach that estimates the same relevant contrast. A change within one group does not, by itself, establish that its assigned regimen differs from the other regimen. The registry does not state which comparison method was used, or report any estimate.

What does an uncertainty interval contribute?

In general, an estimate is more informative when accompanied by a confidence interval. The estimate indicates the direction and size of the observed contrast; the interval communicates uncertainty about that estimate under the method's assumptions. A narrow interval indicates greater precision than a wide interval, but interpretation also depends on the outcome scale and the question of clinical relevance. Because the record reports neither an estimate nor an interval for YBOCS change, the direction, magnitude, and precision of the primary comparison cannot be evaluated.

Why can over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variability is greater than a model assumes. If an analysis assumes less variability than the data contain, its uncertainty estimates may be too small, making results appear more precise than warranted. This issue is especially discussed for count outcomes, where variance assumptions can affect standard errors and tests. The primary endpoint is continuous and is described using a mean and standard deviation. The registry does not report an analysis model or any evidence about over-dispersion, so there is no basis to say it occurred or affected a result in this trial.

What can the planning illustration establish?

The record describes a planning illustration based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between the arms, and a normal approximation. Such a calculation is a hypothetical planning exercise: it asks what sample size might be needed under the stated assumptions to detect a chosen effect. It is not the trial's observed result, and it is not observed power. The registry record does not report a sample-size justification used to design this trial. A planning illustration cannot fill the gap left by the absence of a reported primary-outcome estimate.

What is not specified?

The registry record does not report the primary-outcome model, the exact contrast or test, adjustment for baseline score, covariates, handling of missing values, analysis population, or any prespecified interim analysis. It also does not report a statistical analysis plan. These details matter because choices about modeling, missing outcomes, and analysis populations can affect an estimate and its uncertainty. Without them, readers cannot reproduce or evaluate a primary analysis from the registry entry.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies change in YBOCS as the primary outcome and feasibility of recruitment as a secondary outcome. It also records two outcome measures, but does not give the results or analyses for them. The primary outcome is noted as involving several categories or time points and is not reduced to a single comparison. This means the registry entry does not specify one primary contrast for which a result can be interpreted.

Multiplicity concerns arise in general when several outcomes, time points, groups, or analyses are examined. Testing many contrasts can increase the chance of a seemingly notable finding unless the analysis plan accounts for that multiplicity. The registry record does not report whether an adjustment was planned or used, how outcome categories or time points were selected, or which comparison was considered primary in the analysis. It is therefore not possible to assess multiplicity handling.

Missing-data methods and analysis populations are also not reported. In general, missing outcome measurements can affect estimates if participants with missing values differ from those with observed values. Statistical approaches make different assumptions about such data, so reporting the amount and pattern of missingness and the chosen method is important. The record does not say how missing Week 4 measurements were handled, whether all randomized participants were included in the primary analysis, or whether any other analysis population was defined.

No primary-outcome analysis is listed in the registry information. The absence of these details does not establish that analyses or plans did not exist outside the registry; it means they are not reported in the registry record. Without a defined contrast, analysis population, missing-data approach, and multiplicity strategy, the posted record cannot support a full appraisal of the planned or completed statistical analysis.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event entries list serious events affecting 0 participants in the nabilone group and 0 in the nabilone-and-EX/RP group. The at-risk counts shown for these entries are 9 and 7, respectively. Deaths are recorded as 0 in each group. The entries also list other, non-serious adverse events affecting 1 participant in the nabilone group and 2 in the combination group.

These are counts in the registry record, not estimates of comparative risk. No rates or between-group safety analysis are reported, and the counts should be read alongside their listed at-risk groups rather than treated as a complete safety comparison. The record does not provide event descriptions for the non-serious events, their timing, severity beyond the serious/non-serious categorization, or whether investigators considered them related to study interventions. The serious-event terms list is empty.

Zero serious events recorded in the listed groups does not establish that serious harm is impossible or that the regimens have equivalent safety. A small trial and limited follow-up may not characterize uncommon or later events. The registry record describes the treatment period as 4 weeks but does not provide further safety follow-up details. These entries are a limited account of recorded events, not a comprehensive safety conclusion.

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

The registry record describes a randomized pilot study of nabilone alone versus nabilone combined with EX/RP in adults with OCD. It specifies change in YBOCS score from baseline to Week 4 as the primary outcome and gives the direction used to calculate that change. It also lists recruitment feasibility as a secondary outcome. These details establish what the study set out to compare.

The record does not report a primary-outcome estimate or statistical analysis. It therefore does not show whether YBOCS change differed between the assigned groups, the size or direction of any difference, or the precision of an estimate. The completed status does not substitute for outcome reporting. Nor can the listed adverse-event counts answer the primary efficacy question.

Even if a between-group result were reported, its interpretation would be specific to the comparison: adding therapist-guided EX/RP to a nabilone regimen versus nabilone alone. Since both listed arms include nabilone, the design as described does not directly estimate nabilone versus no nabilone. The unmasked design is another consideration when interpreting outcomes, although the registry does not report who knew assignment or how the YBOCS was administered.

The brief summary states that nabilone is approved for chemotherapy-induced nausea and vomiting and is not FDA-approved for OCD. That regulatory context is not evidence of benefit or harm in this trial. The registry's description as a pilot also does not provide a result. Conclusions about efficacy, clinical importance, or comparative safety require analyses and details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a clearly identified research question can remain unanswered in a registry entry when the outcome analysis is absent. The record supplies the randomized comparison, outcome definition, measurement times, and intervention descriptions. Those details let readers identify the intended estimand in broad terms: a contrast in YBOCS change between nabilone alone and nabilone with EX/RP.

At the same time, the record illustrates why outcome estimates and uncertainty matter. A study's design and completed status do not reveal the observed effect. Without a group contrast and confidence interval, the direction, magnitude, and precision of the primary outcome remain unknown. Listing the scale and time points is not equivalent to reporting the data needed to assess the result.

The comparison also demonstrates the importance of distinguishing a combined treatment question from a component-effect question. Both groups received nabilone, so the randomized contrast concerns the additional EX/RP component within that treatment context. It does not isolate the effect of nabilone itself. Clear interpretation depends on matching claims to the actual treatment contrast.

Finally, the record raises standard appraisal questions about masking, missing outcome data, analysis populations, and multiplicity. These issues are not unusual in statistical review, but the registry does not provide enough detail to resolve them for this trial. The study can be described accurately from its design record, while claims about efficacy or comparative safety must remain limited by the missing results and analysis 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 limitations specific to this trial can be identified from the registry information. The listed enrollment is 16, and the study is described as a pilot. The registry does not provide an outcome estimate or its uncertainty, so readers cannot assess how much information the study yielded about the primary comparison. Nor is a trial-specific sample-size justification reported.

The primary outcome is defined as change from baseline to Week 4, but the entry notes several categories or time points and does not reduce the outcome to a single comparison. This limits the clarity of the intended analysis. No primary analysis is listed, and the record does not specify the model, analysis population, missing-data handling, or multiplicity approach.

The trial is unmasked. The record does not state which participants or study personnel knew assignments, whether outcome assessors were masked, or how the YBOCS assessment was administered. These omissions prevent a detailed assessment of possible assessment or performance effects. The registry also does not give further eligibility criteria, recruitment procedures, or baseline group characteristics in the information.

The safety information is limited to group counts of serious and other adverse events and deaths. Event descriptions, attribution, timing, and follow-up beyond the stated treatment period are not reported. The adverse-event counts therefore cannot characterize the full range or longer-term pattern of harms. These limitations concern what is documented in the registry record; they do not establish what information may be available elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cannabinoid Medication for Adults With OCD — NCT02911324.
• Registry record last updated 2020-08-06; status last verified 2020-07.
• Results first posted 2020-02-28.
• 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.

18. Record Summary

NCT02911324 is a completed, randomized, unmasked, parallel-group Phase 1 and Phase 2 pilot study sponsored by New York State Psychiatric Institute. It concerns adults with obsessive-compulsive disorder and lists enrollment of 16. The registry gives a start date of 2016-09 and a primary completion date of 2019-01.

The two arms are nabilone alone and nabilone with therapist-guided exposure and response prevention therapy. The primary outcome is change in YBOCS score from baseline (Week 0) to Week 4, defined as baseline score minus Week 4 score. Feasibility of recruitment is listed as a secondary outcome.

No primary-outcome analysis or result is reported in the registry entry. The entry also does not report the statistical plan, missing-data approach, analysis population, or multiplicity handling. Safety entries list no serious events or deaths in either group and list other adverse events affecting 1 participant in the nabilone group and 2 in the combination group.