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 A Study of GWP42003 as Adjunctive Therapy in the First Line Treatment of Schizophrenia or Related Psychotic Disorder (NCT02006628), a randomized phase 2 study. The primary outcome is Change From Baseline To End Of Treatment (Day 43) In Positive And Negative Syndrome Scale (PANSS) Total Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02006628 |
| Phase | Phase 2 |
| Condition | Schizophrenia, Schizophrenia-related Psychotic Disorder |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 88 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Jazz Pharmaceuticals |
| Results posted | Yes |
2. Clinical Question
Population
Participants with schizophrenia or a schizophrenia-related psychotic disorder were studied. The primary outcome description defines an ITT analysis set as participants who consented, were randomized, took at least one dose of investigational medicinal product, and had post-baseline efficacy data. It also notes an exclusion for one placebo participant with a Day 1 PANSS total score <60 and one GWP42003 participant with no post-baseline efficacy information.
Intervention
GWP42003 was given as adjunctive therapy alongside existing antipsychotic therapy. The described dose was 1000 mg/day, administered orally as 5 mL in the morning and 5 mL in the evening for six weeks.
Comparator
The comparator was matching oral placebo, administered as 5 mL twice daily for six weeks, alongside existing antipsychotic therapy. The placebo was described as containing 0 mL cannabidiol.
Primary question
The primary outcome was change from baseline to end of treatment, Day 43, in PANSS total score. The registry record does not report the comparative outcome values or an estimated treatment effect, so the recorded information does not establish the direction or precision of the difference between treatment groups.
3. Trial Design
This was a phase 2, randomized, quadruple-masked, placebo-controlled, parallel-group study. It compared GWP42003 with placebo as adjunctive therapy in the first-line treatment of schizophrenia or a related psychotic disorder. Participants continued existing antipsychotic therapy; details about those background treatments are not reported in the registry record.
The registry record lists enrollment of 88. The stated study start was 2014-02-25, and primary completion was 2015-01-08. The study status is completed. The summary describes treatment over six weeks, while the primary endpoint timeframe is Day 1 through Day 43. The GWP42003 arm description specifies an oral dose of 1000 mg/day, given as 5 mL twice daily. Placebo was volume-matched to the 5 mL twice-daily dose.
Random allocation is intended to make treatment groups comparable on average, including for characteristics that were not measured or recorded. It does not guarantee that groups will be identical, particularly in a study of this size. Masking is intended to limit the influence of treatment knowledge on care, participant responses, outcome assessment, or other trial processes. The registry identifies quadruple masking but does not report which specific roles were masked.
A parallel-group design assigns participants to a treatment group for the study rather than comparing different treatments within the same participant. The primary outcome focuses on change in symptom severity over the treatment period. The registry record does not report the allocation ratio, recruitment details, treatment adherence, or whether other procedures differed between groups.
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 | GWP42003 1000 Milligram (mg)/Day | Placebo |
|---|---|---|
| STARTED | 43 | 45 |
| Received at Least 1 Dose of Study Drug | 43 | 45 |
| Intention to Treat (ITT) Analysis Set | 42 | 44 |
| COMPLETED | 40 | 43 |
| NOT COMPLETED | 3 | 2 |
Reasons for not completing this period:
| Reason | GWP42003 1000 Milligram (mg)/Day | Placebo |
|---|---|---|
| Adverse Event | 1 | 1 |
| Withdrawal by Subject | 2 | 1 |
Analysis population for the primary outcome, as defined in the registry: ITT analysis set: all participants who provided informed consent, were randomized to 1 of the treatment groups, took at least 1 dose of IMP, and had post-baseline efficacy data. One placebo participant with a PANSS Total score \<60 at Day 1 and 1 GWP42003 participant with no post-baseline efficacy data were excluded from the ITT analysis set.
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: Safety analysis set: Participants who provided informed consent, were randomized to 1 of the treatment groups, and took at least 1 dose of investigational medicinal product (IMP).
| Characteristic | Unit | GWP42003 1000 mg/Day | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 43 | 45 | 88 | |
| Age, Continuous | years | 40.9 (SD 12.49) | 40.8 (SD 11.00) | 40.8 (SD 11.69) |
| Sex: Female, Male: Female | Participants | 15 | 22 | 37 |
| Sex: Female, Male: Male | Participants | 28 | 23 | 51 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline To End Of Treatment (Day 43) In Positive And Negative Syndrome Scale (PANSS) Total Score, measured over Day 1 through Day 43.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was change from baseline to end of treatment, Day 43, in total score on the Positive and Negative Syndrome Scale (PANSS). The registry describes PANSS as a 30-item scale completed by a trained rater. It assesses positive symptoms, negative symptoms, and general psychopathology associated with schizophrenia. Each item is rated on a 7-point scale, from 1 for absent to 7 for extreme. The total is the sum of the positive, negative, and general psychopathology scores and ranges from 30 to 210; lower scores indicate milder symptom severity.
A change score compares an endpoint measurement with a baseline measurement. It can summarize whether symptom severity moved over the treatment period, while a comparison between randomized groups can estimate how their average changes differed. Change from baseline is useful when the outcome is measured at both the start and end of treatment, because it describes within-participant movement while the randomized-group contrast provides the treatment comparison.
The registry lists the endpoint as a mean with standard deviation. It does not report the group means, standard deviations, change estimates, uncertainty intervals, or a comparative test result for this endpoint. Thus, the measure and its intended interpretation are described, but the recorded outcome information does not quantify the observed change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary endpoint is a continuous score, summarized in the registry as a mean and standard deviation. The registry record does not report the numerical primary outcome results or a between-group effect estimate. It therefore does not establish whether average PANSS change was greater in either group, how large any difference was, or how precisely the difference was estimated. No efficacy conclusion can be drawn from the endpoint description alone.
The record lists 9 outcome measures and 9 analyses, and identifies the trial outcome type as continuous. The primary result is flagged as having several categories or time points and is not reduced to one comparison. That means a single primary comparison cannot be read from the recorded result information. The registry record does not report the values for the multiple categories or time points, nor does it identify which individual comparison should be treated as the main estimate.
Standard deviations describe the spread of participant scores around a group mean. They are not the same as uncertainty around the estimated mean or around a treatment contrast. A confidence interval, when reported, conveys a range of effect values compatible with the data and analysis under its assumptions. No confidence interval for the primary comparison is reported in the registry record. A p-value, if reported, would address compatibility with a specified null hypothesis under model assumptions; it would not by itself describe effect size or clinical importance. The primary p-value is not reported in the registry record.
The randomized, masked, parallel-group design is relevant to interpretation because randomization can reduce systematic baseline differences on average, and masking can reduce some forms of expectation or assessment bias. These design features do not replace outcome estimates, and they do not remove uncertainty due to the observed data or choices made in analysis. Information about the randomization procedure and which trial roles were masked is not reported in the registry record.
The registry describes an ITT analysis set with consent, randomization, at least one dose, and post-baseline efficacy data as conditions for inclusion. The primary outcome description also notes exclusions involving one placebo participant whose Day 1 PANSS total score was <60 and one GWP42003 participant without post-baseline efficacy information. The implications of these exclusions depend on the analysis plan and missing-data handling, which are not reported in the registry record. The recorded summary is therefore insufficient to determine how sensitive the primary comparison was to those decisions.
Safety counts are reported separately from the primary efficacy outcome. The record lists no serious adverse events affecting participants in the GWP42003 group and one in the placebo group; other adverse events affected 8 and 10 participants, respectively. These counts are descriptive. Without further details about event definitions, severity, timing, exposure, and statistical comparisons, they should not be interpreted as a comprehensive comparison of safety.
9. Statistical Methods Explained
The registry presents a randomized, parallel-group comparison of GWP42003 and placebo. The primary outcome is continuous: PANSS total score change from baseline to Day 43, reported in principle as a mean and standard deviation. The registry record does not report the numerical primary outcome results, so statistical concepts can explain how such results are generally interpreted but cannot supply an estimate for this trial.
What does a mean change represent?
General statistical explanation: A mean change is the average of participants’ endpoint scores minus their baseline scores, according to the chosen subtraction convention. A group mean summarizes the average movement in that group, but it does not show how individual participants changed. Participants may have changes that vary widely around the average. The standard deviation describes that variation in scores; it is not itself a measure of the precision of the treatment comparison.
For a randomized trial, the treatment effect of interest is generally a contrast between groups, such as the difference in their average changes or an adjusted difference in endpoint scores. The appropriate contrast depends on the prespecified analysis. A change within one group is not, by itself, an estimate of the effect of treatment relative to placebo. The specific method used for the primary comparison is not reported in the registry record.
How should uncertainty be read?
General statistical explanation: A confidence interval describes uncertainty around an estimated effect under the assumptions of the analysis. A narrower interval indicates greater precision, while a wider interval indicates less precision. Whether an interval includes a value representing no difference can help readers assess compatibility with that value, but the interval also shows the range of effect sizes that remain plausible under the model. It should be considered alongside the point estimate and the clinical meaning of the outcome.
A p-value is not the probability that a treatment is effective, nor does it measure the size or importance of an effect. It is calculated relative to a specified statistical model and null hypothesis. The registry record does not report a p-value or confidence interval for the primary comparison, and it does not report the comparative effect estimate. The strength and precision of the primary evidence therefore cannot be evaluated from the recorded primary outcome information.
Why can score distributions matter?
General statistical explanation: A mean-based analysis is most straightforward when the outcome and model assumptions are suitable for that summary. A bounded scale such as PANSS has a limited possible range, and distributions can be asymmetric or concentrated in particular parts of that range. These features may influence the usefulness of a normal approximation or the behavior of standard errors. The registry record does not report distributional diagnostics or enough outcome data to assess these issues for this trial.
Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. If a model understates variability, its uncertainty estimates may be too small; if it accounts for the variability appropriately, inference can be more reliable. This concept is not a claim that over-dispersion occurred in this study. The registry record does not report a model or diagnostic information that would allow that assessment.
What does masking contribute?
General statistical explanation: Masking can reduce the influence of expectations on experiences, care, or outcome assessment. The registry records quadruple masking, but does not identify the roles covered by that label. Randomization and masking are protections against some sources of bias; neither guarantees that outcome data are complete, that analysis decisions are unbiased, or that estimates are precise. The record does not describe the randomization procedure or the specific methods used to preserve masking.
What are planning illustrations for?
General statistical explanation: A sample-size calculation for a future study asks how many participants per arm might be needed to detect a chosen effect under specified assumptions. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect expressed as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. The registry record does not report the trial’s own sample-size justification or indicate that these illustration assumptions governed the trial’s design.
For any planning illustration based on an observed effect, uncertainty in the observed estimate matters: an imprecise or unusually large estimate can make a future-study calculation unstable. A planning value is not a guarantee that a future study will detect an effect, and it is not a substitute for the trial’s actual outcome estimate. The numerical primary effect and the planning sample-size values are not reported in the registry record.
What can be inferred from the posted information?
The design and endpoint are identifiable, but the principal efficacy comparison is not numerically available in the registry record. Without the group outcome summaries, treatment contrast, uncertainty interval, and analysis details, readers cannot assess the magnitude, direction, or precision of the observed primary result. The trial’s masking and randomization describe design features; they do not fill in those missing results.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when an analysis considers more than one outcome, comparison, category, or time point. With multiple statistical tests, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for the family of tests. This is a general statistical issue, not evidence that any particular result in this study is false.
The registry lists 9 outcome measures and 9 analyses, and flags the primary outcome as having several categories or time points rather than reducing it to one comparison. The record does not report the individual primary outcome results or a multiplicity adjustment strategy. It is therefore not possible to determine from the registry record how the different categories or time points were handled in inference, or which comparison was designated for a single primary interpretation.
The primary outcome description identifies an ITT analysis set as participants who consented, were randomized, took at least one dose of investigational medicinal product, and had post-baseline efficacy data. It also notes that one placebo participant with a Day 1 PANSS total score <60 and one GWP42003 participant with no post-baseline efficacy information were excluded from the described set. The record’s endpoint-population wording is incomplete, and further details about the analysis population are not reported in the registry record.
Missing outcome data can affect both the estimate and its uncertainty. The impact depends on why values are missing, the assumptions used, and the statistical method for handling them. The registry record does not report the extent of missing primary outcome data beyond the noted participant, the reasons for missingness, an imputation method, or sensitivity analyses. It also does not report an interim-analysis plan or a detailed statistical analysis plan. These omissions limit assessment of whether the reported analysis choices could influence the treatment comparison.
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 |
|---|---|---|---|
| GWP42003 1000 mg/Day | 0 | 43 | 0.0% |
| Placebo | 1 | 45 | 2.2% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| GWP42003 1000 mg/Day | 8 of 43 |
| Placebo | 10 of 45 |
Most frequent serious adverse event terms
| Event term | Organ system | GWP42003 1000 mg/Day | Placebo |
|---|---|---|---|
| Schizophrenia | Psychiatric disorders | 0 of 43 | 1 of 45 |
Most frequent non-serious adverse event terms
| Event term | Organ system | GWP42003 1000 mg/Day | Placebo |
|---|---|---|---|
| Headache | Nervous system disorders | 3 of 43 | 4 of 45 |
| Diarrhoea | Gastrointestinal disorders | 4 of 43 | 2 of 45 |
| Nausea | Gastrointestinal disorders | 3 of 43 | 0 of 45 |
| Somnolence | Nervous system disorders | 0 of 43 | 3 of 45 |
| Insomnia | Psychiatric disorders | 0 of 43 | 2 of 45 |
Serious events with the highest arm-level rate: schizophrenia (2.2%).
The registry lists serious adverse events affecting 0 of 43 participants at risk in the GWP42003 group and 1 of 45 participants at risk in the placebo group. Other adverse events affected 8 of 43 participants at risk in the GWP42003 group and 10 of 45 participants at risk in the placebo group. These are participant counts as recorded, not estimates of a treatment effect.
The listed serious adverse event term is schizophrenia, reported as 2.2%. The record does not clearly assign that term to a specific group in the information available. Death counts are not reported in the registry record. The absence of a reported count should not be interpreted as confirmation that no deaths occurred.
Adverse-event counts are most informative when read with definitions, observation time, event severity, duration, exposure, and handling of repeated events. Those details and a formal statistical comparison are not reported in the registry record. The counts should therefore be treated as descriptive safety information rather than as evidence that one treatment has a better or worse safety profile.
12. What the Result Does, and Does Not, Mean
The record describes a randomized comparison of adjunctive GWP42003 with placebo in people with schizophrenia or a related psychotic disorder. It identifies PANSS total score change from baseline to Day 43 as the primary outcome. These details clarify what the trial was designed to examine, but they do not establish what the comparative outcome was.
The registry record does not report the primary group means, standard deviations, treatment contrast, confidence interval, or p-value. Consequently, it is not possible to state whether PANSS scores changed more in one group, how large any difference was, or how precisely it was estimated. The absence of those results is not evidence that there was no difference; it means the recorded information does not quantify the comparison.
Even when a difference is reported, statistical evidence and clinical importance are not interchangeable. A small estimate can be precise, a larger estimate can be uncertain, and interpretation depends on the scale, population, analysis, and relevant clinical context. The registry description explains the score’s range and direction, but it does not provide a threshold for a clinically important change. Such a threshold is not reported in the registry record.
The study’s randomized and masked design is relevant to the credibility of a treatment comparison, but design features alone cannot demonstrate benefit or harm. The record also does not provide enough information to assess adherence, missing-data assumptions, the handling of multiple outcome comparisons, or whether the analysis was prespecified. These uncertainties are separate from the observed outcome itself, which is not numerically reported.
Safety figures offer a limited descriptive account of serious and other adverse events. They do not support a broad conclusion about comparative safety without more information on event definitions, timing, exposure, and analysis. The results should be understood as incomplete evidence in the registry record, not as a recommendation about treatment or an indication for an individual patient.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized, masked, placebo-controlled comparison of an adjunctive treatment, with a continuous symptom-scale endpoint measured over a defined treatment period. Such a design makes the contrast between treatment groups central: the relevant evidence is not simply whether either group changed, but how the groups’ changes compared and how uncertain that contrast was.
The registry record illustrates why a clear endpoint description is not a substitute for outcome results. It explains what PANSS measures, how the total score is constructed, and the direction of the scale, but it does not report the numerical primary comparison. Readers can identify the planned clinical question without being able to judge the size or precision of its answer.
The record also highlights the importance of specifying analysis populations and missing-data procedures. The primary outcome description names an ITT analysis set but notes exclusions related to a low baseline score and missing post-baseline efficacy information. Without full population details and sensitivity analyses, it is difficult to assess how these decisions might affect interpretation.
Finally, the primary outcome is flagged as involving several categories or time points. When multiple comparisons are possible, a clear prespecified analysis and appropriate handling of multiplicity help readers distinguish the main inference from exploratory findings. Those details are not reported in the registry record. These issues matter because transparent statistical reporting is necessary to evaluate an estimate, not merely to identify the trial’s design and endpoint.
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 principal limitation for interpreting efficacy is that the registry record does not report numerical results for the primary PANSS comparison. Group means, standard deviations, the treatment contrast, and its uncertainty are unavailable. The record therefore does not support a conclusion about the direction, magnitude, or precision of the primary result.
The outcome is flagged as having several categories or time points, but the individual comparisons and any multiplicity approach are not reported in the registry record. The detailed statistical analysis plan, sample-size justification, randomization procedure, and specific roles covered by quadruple masking are also not reported. The planning assumptions described in the record should not be mistaken for the trial’s own design justification.
The primary outcome population description names eligibility conditions for the ITT analysis set and notes exclusions involving one placebo participant with a Day 1 PANSS total score <60 and one GWP42003 participant without post-baseline efficacy information. The description is incomplete, and the record does not report sufficient details about all missing outcome data, reasons for missingness, imputation, or sensitivity analyses.
Safety reporting is also limited: counts are available for serious and other adverse events, but deaths are not reported, and the serious-event term is not clearly assigned to a treatment group. Further information about event definitions, severity, follow-up, exposure, and statistical comparison is not reported in the registry record. These limitations concern what can be evaluated from the record; they do not establish that any particular bias or problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of GWP42003 as Adjunctive Therapy in the First Line Treatment of Schizophrenia or Related Psychotic Disorder — NCT02006628.
- Registry record last updated 2022-09-28; status last verified 2022-09.
- Results first posted 2019-07-26.
- 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
The registry identifies NCT02006628 as a completed phase 2, randomized, quadruple-masked, parallel-group study of GWP42003 versus placebo as adjunctive therapy for schizophrenia or a related psychotic disorder. Enrollment is listed as 88. The study start was 2014-02-25, and primary completion was 2015-01-08.
The primary outcome was change from baseline to Day 43 in PANSS total score, a mean-based measure of symptom severity. The record describes a six-week oral regimen of GWP42003 1000 mg/day or matching placebo, alongside existing antipsychotic therapy. Numerical comparative primary results are not reported in the registry record. Serious and other adverse-event counts are listed, but the record does not provide enough detail for a comprehensive comparative safety interpretation.