Cannabidiol Oral Solution for the Treatment of Patients With Prader-Willi Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cannabidiol Oral Solution for the Treatment of Patients With Prader-Willi Syndrome (NCT02844933), a randomized phase 2 study. The primary outcome is Change From Baseline in Hyperphagia Behavior as Measured by the Hyperphagia Questionnaire for Clinical Trials (HQ-CT).

2. Clinical Question

The broader study objectives also included efficacy, safety and tolerability, quality of life, and physical activity. Listed secondary outcomes include total body weight, responder rate, Patient Global Impression of Change, eating behavior, quality-of-life measures, and physical-activity and fatigue measures. The registry record does not report results for these outcomes in the registry record recorded for this analysis.

3. Trial Design

This was a Phase 2, randomized, double-blind, parallel-group, placebo-controlled study of cannabidiol oral solution in patients with Prader-Willi syndrome. The sponsor listed in the registry record is Radius Pharmaceuticals, Inc. The recorded enrollment is 7, and the study status is terminated.

The registry record gives a study start date of 2018-05-09 and a primary completion date of 2019-07-17. It does not state why the study was terminated. The reason for termination, the timing of the decision, and whether the planned recruitment or follow-up was completed are not reported in the registry record.

Participants were assigned to cannabidiol or matching placebo. The cannabidiol arm description specifies 40 milligram/kilogram/day [40 mg/kg/day] in two daily doses with a standard meal. The placebo was also divided into two daily doses with a standard meal. The record describes the study as double-blind but does not explain which groups of people were masked or how masking was maintained.

The primary outcome was change in HQ-CT score from Baseline to Week 13. The primary outcome population is described as all participants who received at least 1 dose of study drug. The record lists additional outcomes concerning body weight, responder status, patient global impression, eating behavior, quality of life, and physical activity. It does not report detailed allocation procedures, planned enrollment rationale, follow-up completion, or the statistical analysis plan. Those design details are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Approximately 66 participants aged 8 to 17 years, inclusive, with a genetically confirmed diagnosis of Prader-Willi Syndrome were planned to be enrolled in the study. The previous Sponsor prematurely terminated the study prior to reaching the planned enrollment. Therefore, only 7 participants participated in the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All participants who received at least 1 dose of study drug

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: All participants who were enrolled and received at least 1 dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Hyperphagia Behavior as Measured by the Hyperphagia Questionnaire for Clinical Trials (HQ-CT), measured over Baseline, Week 13.

The primary endpoint concerns change in hyperphagia behavior, measured with the Hyperphagia Questionnaire for Clinical Trials (HQ-CT). The registry record describes the questionnaire as a measure completed by clinicians specializing in Prader-Willi syndrome. It produces a score from 0 to 36, with higher scores representing more severe abnormal food-related behaviors.

The change is defined as the Week 13 value minus the Baseline value. Under that definition, a negative change represents a lower score at Week 13 than at Baseline; a positive change represents a higher score. This describes the scale’s arithmetic direction, not an observed trial result. The registry record gives the endpoint’s summary measure as the median and its dispersion as the full range, but it does not report the actual group summaries or changes.

Hyperphagia-related behavior is a central study focus because the primary objective was to assess the intervention’s effect on this behavior in patients with PWS. A standardized questionnaire provides a structured way to record clinician-assessed behavior at the specified time points. The registry record does not report measurement properties, a threshold for meaningful change, or the rationale for selecting the median and full range. The primary endpoint’s observed results and between-group comparison are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the trial as randomized, double-blind, parallel, and placebo-controlled. These terms describe features of the planned comparison. Random allocation is intended to make treatment assignment independent of measured and unmeasured participant characteristics on average. A placebo comparator provides a reference group under the trial conditions. Double-blinding is intended to limit differences in expectations or assessment that could affect outcomes. These are general purposes of the methods; the registry record does not provide details about the allocation sequence, concealment, or masking procedures used in this study.

What does the primary summary measure describe?

The primary outcome is a change score, calculated as the Week 13 HQ-CT value minus the Baseline value. The score ranges from 0 to 36, and higher scores indicate more severe abnormal food-related behaviors. The record specifies the median as the summary measure and the full range as the dispersion measure. A median describes the middle of the ordered observations and is less influenced by extreme values than a mean. The full range describes the lowest and highest observed values. These are general statistical properties; the actual medians and ranges are not reported in the registry record.

Using a median may be useful when a distribution is skewed or contains extreme observations, but the record does not state why it selected this summary. A full range can convey the spread of observed values, though it depends on the most extreme observations and does not, by itself, show how values are distributed between them. For a small dataset, individual observations can strongly affect both summaries. The posted information does not include the participant-level values needed to inspect the distribution.

Why is a between-group estimate important?

A change within an arm answers how its participants’ scores changed over time, but the randomized comparison concerns how outcomes differed between the cannabidiol and placebo groups. A between-group estimate would quantify that contrast, while a confidence interval would express the range of values compatible with the data under the statistical model. A narrow interval generally indicates greater precision than a wide interval. These are general explanations; no between-group estimate or confidence interval for the primary outcome is reported in the registry record.

A significance test, if reported, would address compatibility with a specified null hypothesis under its assumptions. A p-value would not measure the size or clinical importance of an effect. The registry record does not report a primary-outcome p-value, confidence interval, or test result. It also does not report the statistical test or model used for the primary comparison. No statistical analysis plan is reported in the registry record.

What can the enrollment count tell readers?

The recorded enrollment is 7. Enrollment is not necessarily the same as the number with outcome data at each assessment. The primary population is described as participants who received at least 1 dose, but the number assessed at Baseline and Week 13 is not reported in the registry record. Without those details, readers cannot judge the completeness of endpoint observations or the precision of the comparison. Small datasets also make estimates more sensitive to each participant’s outcome; this is a general statistical consideration, not a calculated finding about the unreported results.

The registry record includes a general planning illustration based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such calculations are planning illustrations, not observed power or evidence that a trial was adequately powered. The record does not report a sample-size justification for this study, and no specific planning result is reported in the registry record recorded for this analysis. The observed primary effect itself is not reported, so the planning assumptions do not provide an interpretable estimate of the trial’s outcome.

How should multiple outcomes be considered?

The record lists several secondary outcomes in addition to the primary endpoint. When many outcomes or comparisons are examined, the chance of at least one apparently unusual result can increase. Statistical approaches to multiplicity can address this issue, but the record does not report whether any adjustment was planned or performed. The listed outcomes should therefore be understood as outcome domains, not as evidence of positive or negative findings. Their results are not reported in the registry record.

Over-dispersion is a general concern when count data vary more than a chosen statistical model expects; an approach that accounts for over-dispersion can produce more reliable uncertainty estimates in such settings. The primary endpoint is a questionnaire change score, and the registry record does not report a model or indicate that over-dispersion was assessed. It would not be appropriate to infer an analysis method from the outcome description alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry record identifies one primary outcome and lists several secondary outcomes. It does not report a statistical analysis plan, a multiplicity strategy, or whether secondary comparisons were considered confirmatory or exploratory. When a study evaluates multiple outcomes, tests, or time points, the possibility of chance findings can increase. Adjustment methods can address that issue, but there is no basis in the registry record to say that any particular method was used.

The record does not provide primary outcome values or secondary outcome results. It also does not report missing-data counts, reasons for missingness, imputation methods, sensitivity analyses, or rules for excluding observations. These omissions matter because the primary outcome requires measurements at Baseline and Week 13. The stated primary population consists of participants who received at least 1 dose, but the record does not give the number contributing paired measurements or explain how incomplete data were handled.

Randomization does not eliminate the need to describe missing outcomes or define the analysis population. If some participants lack follow-up data, the available-case results can differ from results under other assumptions about those missing measurements. This is a general issue; the registry record does not provide the information needed to assess its relevance to this trial. It also does not report whether analyses followed an intention-to-treat principle, a per-protocol approach, or another specified population. No conclusions about multiplicity control or missing-data handling can be drawn from the posted record.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry record separates serious adverse events from other adverse events. In the cannabidiol group, 0 serious adverse events are recorded among 4 participants at risk; in the placebo group, 0 are recorded among 3 participants at risk. The record lists no serious-event terms. The zero counts mean that no serious events are recorded in these group entries; they do not establish that serious events are impossible or that the groups have equivalent safety.

Other adverse events are recorded for 4 of 4 participants at risk in the cannabidiol group and 2 of 3 in the placebo group. These are counts from the registry record, not adjusted comparisons. The record does not provide event types, severity details, timing, recurrence, or an analysis comparing groups for these entries. It also does not explain whether the safety population and primary-outcome population were identical.

Adverse-event counts should be interpreted in light of the limited enrollment recorded. Such counts describe what was recorded in this study but cannot precisely characterize uncommon events or establish a comparative risk difference. The registry record does not provide enough detail to infer causation or to assess the relative safety of the interventions.

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

This trial’s registry record describes an attempt to compare cannabidiol oral solution with matching placebo for hyperphagia-related behavior in patients with Prader-Willi syndrome. It specifies a randomized, double-blind, parallel-group design and defines the primary outcome as change in HQ-CT score from Baseline to Week 13. It also records enrollment of 7 and a terminated study status.

However, the record does not report the primary outcome values, a between-group effect estimate, a confidence interval, or a p-value. It therefore does not establish whether the primary outcome favored either group, whether the groups were similar, or how precise a comparison might be. The listed secondary outcomes likewise have no results reported in the registry record. The outcome definitions and study objectives are not substitutes for outcome findings.

The adverse-event entries document no serious adverse events in either group and record other adverse events in both groups. These observations describe the entries for this study; they do not prove that serious events cannot occur, establish a safety difference, or support a broad safety conclusion. The record’s limited enrollment and absent event details constrain interpretation.

Study termination is part of the record, but its reason is not reported in the registry record. It should not be attributed to a particular safety, efficacy, recruitment, or operational issue without supporting information. Likewise, the enrollment count alone does not reveal whether the study stopped early relative to its plan, because the planned enrollment and termination rationale are not reported.

The defensible reading is therefore narrow: the registry record documents the trial design, primary measure, and certain adverse-event counts, but it does not report efficacy results or a treatment-effect estimate. No conclusion that cannabidiol does or does not change hyperphagia-related behavior can be drawn from these registry entries.

13. Why This Trial Matters Statistically

This study is statistically notable because its registry record pairs a clearly described clinical question with a very limited reported enrollment and no posted primary outcome comparison. That combination makes the distinction between a trial’s design and its results especially important. Randomization and blinding describe how a comparison was intended to be conducted; they do not provide evidence about the outcome unless the group data and analysis are reported.

The endpoint also illustrates the importance of specifying direction. The HQ-CT score runs from 0 to 36, with higher scores representing more severe abnormal food-related behaviors, and change is defined as the later Week 13 value minus the Baseline value. That definition helps readers understand what a reported change would mean. Yet without observed changes, no effect direction or magnitude can be inferred.

Enrollment of 7 and the absence of outcome summaries limit the statistical conclusions available from this record. A study can be relevant to a research question even when its registry record does not permit an estimate of treatment effect. In that circumstance, uncertainty is not a finding of no effect: it reflects the absence of reported comparative outcome data.

The recorded safety counts similarly show why raw observations and conclusions must be distinguished. The entries are useful descriptions of events recorded in the study, but they do not amount to a precise or comprehensive comparison. The reason for termination and the statistical analysis plan are not reported in the registry record, leaving important context unavailable.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation for interpretation is that the registry record does not report the primary endpoint results. It gives no group-level HQ-CT changes, between-group estimate, confidence interval, or test result. The secondary outcome results are also not reported in the registry record. The trial’s clinical question and endpoint definition can therefore be described, but the reported information does not permit an efficacy comparison.

The record reports enrollment of 7 but does not state how many participants contributed Baseline and Week 13 measurements, completed follow-up, or were included in an analysis. Although it defines the primary outcome population as participants who received at least 1 dose, it does not describe missing-data handling or provide a participant flow. These gaps prevent assessment of outcome completeness and analysis-population details.

The study is marked terminated, but the reason for termination and the planned enrollment are not reported in the registry record. The record also does not report the allocation procedure, masking details, statistical analysis plan, sample-size justification, or multiplicity strategy. These missing details limit assessment of the methods beyond the broad design labels.

The safety information gives serious and other adverse-event counts but does not provide event descriptions, timing, severity, or a comparative analysis. The small enrollment recorded also means that the safety entries should be treated as descriptive rather than as a precise characterization. These limitations are specific to the information available in the registry record and do not establish why data or details are absent.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cannabidiol Oral Solution for the Treatment of Patients With Prader-Willi Syndrome — NCT02844933.
• Registry record last updated 2023-08-01; status last verified 2023-07.
• Results first posted 2023-08-01.
• 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 a Phase 2, randomized, double-blind, parallel, placebo-controlled study of cannabidiol oral solution in patients with Prader-Willi syndrome. Enrollment is recorded as 7, and the study status is terminated. The listed sponsor is Radius Pharmaceuticals, Inc.

The primary outcome was change in HQ-CT score from Baseline to Week 13 among participants who received at least 1 dose. The scale ranges from 0 to 36, with higher scores indicating more severe abnormal food-related behaviors. The record does not report primary outcome results or a between-group estimate.

Serious adverse events are recorded as 0 among 4 at risk in the cannabidiol group and 0 among 3 at risk in the placebo group. Other adverse events are recorded for 4 of 4 and 2 of 3 at risk, respectively. The reason for termination, detailed statistical plan, missing-data handling, and outcome results are not reported in the registry record.