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 Treatment on Iatrogenic Weight Gain and Dyslipidaemia Associated With Olanzapine (NCT01491490), a randomized phase 2 study. The primary outcome is Change in Bodyweight..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01491490 |
| Phase | Phase 2 |
| Condition | Schizophrenia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 2 |
| Arms in the primary outcome | 2 |
| Lead sponsor | GW Research Ltd |
| Results posted | Yes |
2. Clinical Question
Population
Adults with functional psychosis, including schizophrenia or other non-affective psychosis, taking olanzapine and showing weight gain attributed to that treatment. The brief summary specifies age 18 years and above and olanzapine treatment for no more than 3 months.
Intervention
A 40:1 ratio of GWP42003 and GWP42004, given alongside existing olanzapine treatment. The planned treatment duration was 6 weeks.
Comparator
Placebo alongside existing olanzapine treatment. The brief summary describes equal random allocation between the combination and placebo groups.
Primary question
How did body weight change from baseline after 6 weeks in the combination group compared with placebo among people receiving olanzapine?
The clinical question is framed around a treatment-associated concern: weight gain and metabolic problems are described in the registry summary as associated with olanzapine. The study was a pilot, and the record also describes interest in cholesterol, other metabolic measures, and possible augmentation of olanzapine’s antipsychotic effect. However, the posted primary outcome is bodyweight change; the record does not post results for those other aims. The central statistical question is therefore whether the recorded bodyweight results support a reliable comparison between the randomized groups. The posted values alone do not answer that question because no comparative analysis or measure of uncertainty is reported.
3. Trial Design
The registry describes a randomized, parallel-group, placebo-controlled pilot study in Phase 2. Its design entry lists triple masking, while the brief study summary describes the study as double-blind. The registry record does not explain this difference in masking descriptions. The planned groups were the GWP42003:GWP42004 combination at a 40:1 ratio and placebo, used alongside olanzapine. The summary says that allocation was to be equal between the groups.
The stated treatment period was 6 weeks, with a baseline period of variable length and a one-week follow-up. The primary outcome was assessed 6 weeks from baseline, described also as after 42 days. The study began in 2011-10, had a primary completion date of 2012-10, and is marked terminated. The reason for termination is not reported in the registry record.
The registry’s overall enrollment field reports 2, and each arm’s posted outcome summary has a count of 1. This is an extremely limited basis for estimating a treatment-group contrast. Although randomization can protect comparisons from systematic allocation differences in a sufficiently informative trial, it does not guarantee that the groups will be balanced in a very small pilot. The record does not report a randomization sequence method, allocation concealment procedure, or details of masking implementation.
The intervention and placebo are both listed as drug interventions, but the arm descriptions are blank. The record does not report a detailed dosing schedule, adherence information, or the characteristics of participants who entered the outcome analysis. These omissions limit the ability to assess implementation and the relationship between planned and analyzed populations.
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: There were a high proportion of screen failures due to most subjects failing to comply with one or more of the eligibility criteria.
Overall Study
| Stage | GWP42003 : GWP42004 (40:1) | Placebo |
|---|---|---|
| STARTED | 1 | 1 |
| COMPLETED | 1 | 1 |
| NOT COMPLETED | 0 | 0 |
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: Only two subjects of a planned 60 were randomised due to early termination of the study due to problems with recruitment.
| Characteristic | Unit | GWP42003 : GWP42004 (40:1) | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 1 | 1 | 2 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 1 | 2 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 24 (SD NA) | 37 (SD NA) | 30.5 (SD 6.5) |
| Sex: Female, Male: Female | Participants | 1 | 1 | 2 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Region of Enrollment: United Kingdom | participants | 1 | 1 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Bodyweight., measured over 6 weeks from Baseline..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Kg |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is change in bodyweight, measured in kilograms, from baseline at 6 weeks. The record describes the aim as comparing the change after 42 days between the 40:1 GWP42003:GWP42004 group and placebo in people receiving olanzapine for schizophrenia or other non-affective psychosis.
Weight is a direct, measurable outcome relevant to the study’s stated concern about weight gain associated with olanzapine. In general, measuring change from baseline can account for the fact that people may begin treatment at different bodyweights, while a comparison between randomized groups can help distinguish a treatment-associated pattern from changes that might occur over time in either group. That general rationale does not establish that the comparison was unbiased or precise in this particular study.
The registry posts a value of 3.6 kg for the combination arm and 1.0 kg for placebo. It does not provide a spread measure, confidence interval, or comparative estimate. The sign convention and any additional detail needed to interpret whether these values represent gain or loss are not reported in the registry record. Thus, the endpoint definition is clear, but the posted values do not establish the direction or precision of a between-group effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record reports primary bodyweight values of 3.6 kg for GWP42003:GWP42004 and 1.0 kg for placebo, with a count of 1 in each arm. These are arm-level results, not a reported estimate of the difference between groups. The registry does not provide a confidence interval, standard deviation, standard error, or other measure of variability. It also lists no posted analyses. As a result, the precision and statistical compatibility of the group results cannot be assessed from the registry record.
The outcome is described as change from baseline, but the registry’s results do not state the sign convention or provide further clarification of the values. It would therefore be unsafe to interpret the values as weight gain or weight loss, or to infer the direction of a treatment effect, from the numbers alone. No statistical test result or p-value is posted for this primary comparison.
The very small arm summaries make the absence of uncertainty information especially consequential. General statistical context: a point estimate describes the observed result in the analyzed data, whereas a confidence interval describes a range of values compatible with the data under the assumptions of the analysis. A point estimate based on very little information can be highly unstable. Without a measure of spread or a reported interval, readers cannot tell how much the estimates might vary with different participants or repeated sampling.
The study is identified as a pilot and marked terminated. Those details provide context for the record but do not explain why the study ended, whether the termination affected data collection, or whether the planned analysis was completed. The reason for termination and the statistical analysis plan are not reported in the registry record. The record reports enrollment of 2, but does not describe a sample-size justification or indicate whether the study was intended to estimate a particular treatment effect with a specified level of precision.
The safety summaries list zero serious events affecting participants in either arm, with one participant at risk in each arm. For other adverse events, the record lists one affected participant in the combination arm and zero in the placebo arm, again with one at risk in each arm. The small arm counts mean that these observations should be read as descriptive counts, not as reliable estimates of comparative safety. Deaths are not reported in the registry record.
Overall, the record documents a randomized pilot and posts arm-level values for its primary outcome, but it does not support a precise comparative conclusion. The reported results should not be treated as evidence that the combination does or does not change bodyweight relative to placebo. The missing comparative analysis, measures of variability, and information about the analyzed population prevent a fuller statistical interpretation.
9. Statistical Methods Explained
What does an arm-level value represent?
The posted 3.6 kg and 1.0 kg values summarize the primary outcome separately by randomized group. An arm-level value is not, by itself, the treatment contrast. A comparison normally requires an estimate of how the outcome differs between groups, together with a description of uncertainty. The registry record does not post that comparative estimate or an analysis result. No further arithmetic contrast should be inferred from the arm summaries, particularly because the record does not report dispersion or clarify the sign convention.
General statistical context: a point estimate is a compact description of the observed data. It does not reveal how variable individual outcomes were or how precisely the underlying group effect has been estimated. Measures such as a standard deviation describe variation among observations; a standard error describes the sampling uncertainty of an estimate; a confidence interval expresses a range of values compatible with the data under specified assumptions. None of these measures is reported for this endpoint.
Why does uncertainty matter?
General statistical context: uncertainty is important because results from a small sample can change substantially if different participants are observed. A confidence interval is not a guarantee that the true effect lies in the interval, nor does it measure the probability that a particular treatment effect is true. It is an interval procedure whose interpretation depends on the statistical model and its assumptions. Without an interval or the information needed to assess variability, the precision of the posted values is unknown.
A p-value, when reported, evaluates how compatible the data are with a specified null model under the assumptions of a statistical test. It does not measure the size or clinical importance of an effect, and it is not the probability that the null hypothesis is true. The registry posts no analysis results for this primary outcome, so there is no reported p-value to interpret. A result cannot be classified as statistically significant or not significant from the arm summaries alone.
What can randomization establish?
General statistical context: random allocation is intended to make treatment assignment independent of measured and unmeasured participant characteristics, on average over repeated randomizations. It supports causal interpretation when the trial is conducted and analyzed appropriately. In a very small study, randomization does not ensure that the groups will have similar baseline characteristics. The record does not provide baseline outcome values or participant characteristics for assessing group balance, nor does it describe the allocation procedure in detail.
The record identifies a parallel-group randomized design and placebo control. It does not report the statistical analysis plan, whether the primary comparison was adjusted for baseline bodyweight, how participants were handled after discontinuation, or which analysis population was used. These details matter because different analysis choices can affect the treatment estimate, especially when data are sparse or incomplete.
How should planning illustrations be read?
The registry’s planning description specifies a two-sided significance level of 0.05, equal allocation, and a normal approximation for illustrations based on fractions of the observed effect. These are planning assumptions, not a description of the trial’s own design justification. Any resulting sample-size values are illustrations of the number of participants per arm under those assumptions, not observed power and not evidence about the study’s actual ability to detect an effect. The registry record does not report the original sample-size justification or a planned target tied to a prespecified clinically meaningful difference.
General statistical context: sample-size planning depends on the effect a study aims to detect, outcome variability, the chosen significance level, desired power, and design features. Planning based on an observed effect can be particularly unstable when the underlying result comes from a very small sample. A planning calculation does not improve the precision of the observed estimate and cannot substitute for a confidence interval or a completed comparative analysis.
What does the count outcome imply for analysis?
The record classifies the posted primary results as a count-type outcome and indicates that values were missing or not estimable for a two-arm comparison. It lists zero posted analyses. For this reason, the registry does not offer an inferential comparison to interpret. General statistical context: an analysis method should reflect how the outcome is measured and how its variability behaves. Count data may be modeled with methods suited to counts, while a continuous change score may be analyzed with methods suited to measurements. The classification and available summary information alone do not establish which model was appropriate.
General statistical context: over-dispersion occurs when count variability exceeds what a chosen model expects. If present, it can make standard errors too small and confidence intervals too narrow unless the analysis accounts for it. This is a general consideration, not a reported feature of this trial. The record does not provide the data or model results needed to evaluate over-dispersion, fit, or alternative analyses.
In general, a robust interpretation would distinguish the planned endpoint, the observed arm summaries, and the prespecified statistical contrast. For this trial, the endpoint and arm summaries are posted, but the comparison, uncertainty estimates, analysis population, and analysis plan are not reported in the registry record. The available statistical evidence therefore remains descriptive and limited.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, change in bodyweight, and no posted secondary outcome results. The study summary also describes interest in cholesterol, other metabolic parameters, and possible augmentation of antipsychotic effect, but results for those aims are not reported in the registry record. The record does not describe whether additional outcomes or analyses were prespecified, or how any multiplicity across outcomes or analyses was handled.
General statistical context: multiplicity arises when several hypotheses or outcomes are tested. Repeated testing can increase the chance of at least one apparently unusual result even when no true effect exists. A statistical plan may address this through a prespecified hierarchy, adjusted significance thresholds, or other approaches. No such plan is reported, so it is not possible to determine whether or how multiplicity was considered.
Missing-data methods and analysis populations are also not reported in the registry record. The posted arm counts are 1 per group, but the record does not explain whether these counts represent all randomized participants, participants who completed treatment, or a particular analysis set. It gives no account of missing outcome values, withdrawals, protocol deviations, or imputation methods. The termination status makes these details relevant, but the registry does not explain any connection between termination and the completeness of the data.
General statistical context: excluding participants with missing outcomes can undermine the balance created by randomization if missingness is related to treatment or outcome. Imputation can introduce its own assumptions, so the approach and sensitivity analyses matter. Because no missing-data methods or population definitions are posted, readers cannot assess these issues for this study.
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 : GWP42004 (40:1) | 0 | 1 | 0.0% |
| Placebo | 0 | 1 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| GWP42003 : GWP42004 (40:1) | 1 of 1 |
| Placebo | 0 of 1 |
Most frequent non-serious adverse event terms
| Event term | Organ system | GWP42003 : GWP42004 (40:1) | Placebo |
|---|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 1 of 1 | 0 of 1 |
The serious adverse event summary lists zero affected participants among the one at risk in the GWP42003:GWP42004 arm, and zero among the one at risk in the placebo arm. These are reported counts, not evidence that serious adverse events could not occur. The registry lists no serious adverse event terms. Death counts are not reported in the registry record.
For other adverse events, the record lists one affected participant among the one at risk in the combination arm and zero among the one at risk in the placebo arm. These counts describe what was recorded in this small study; they do not establish a comparative risk or a treatment-related cause. No event-level details or statistical comparison are posted.
General statistical context: adverse-event counts are difficult to compare when the number of participants observed is very small. A zero count does not establish zero underlying risk, and a difference in observed counts does not by itself establish that treatment caused an event. Interpretation also depends on the event definitions, observation period, exposure, and how events were collected. The record specifies a planned 6-week treatment period but does not report the exposure-adjusted safety analysis or additional details needed for broader conclusions.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, placebo-controlled pilot was registered to compare a 40:1 combination of GWP42003 and GWP42004 with placebo alongside olanzapine. It identifies change in bodyweight at 6 weeks as the primary outcome and posts arm-level values of 3.6 kg and 1.0 kg. It also reports a count of 1 in each arm. These registry entries describe the registered study and its posted summaries.
The record does not establish the direction or size of a reliable between-group effect. The values are not accompanied by a stated sign convention, a comparative estimate, a variability measure, a confidence interval, or a test result. No analyses are posted. Consequently, the numbers cannot show how precisely the group contrast was estimated or whether it is compatible with a range of possible effects.
They also do not establish whether the combination changed bodyweight relative to placebo, whether any change was caused by treatment, or whether the treatment is effective or ineffective. Such conclusions would require an interpretable comparison and adequate information about uncertainty, analysis methods, and participants included. A pilot label does not by itself specify the study’s statistical purpose or make sparse results conclusive.
The safety counts are similarly descriptive. Zero serious adverse events are listed in each arm, and other adverse events are recorded in one combination-arm participant and none in the placebo arm. The limited counts cannot establish comparative safety. The registry’s terminated status is known, but the reason for termination is not reported in the registry record; it cannot be used to infer why the study ended or how termination affected the results.
The most defensible reading is therefore narrow: the registry records a small randomized pilot with posted bodyweight values and sparse safety counts, but does not provide the analysis or precision information needed for a dependable treatment comparison.
13. Why This Trial Matters Statistically
This trial illustrates the distinction between a registered research question and an answer supported by statistical evidence. The primary question is recognizable: compare change in bodyweight between a combination group and placebo among people taking olanzapine. The record also provides arm-level values. But without a comparative estimate and uncertainty measures, the central statistical question remains unresolved in the posted results.
The record is particularly instructive about the limits of very small studies. Randomization is a design strength in principle, but it cannot make sparse observations precise. A single outcome value in each arm offers little information about variability, baseline balance, or how stable the group contrast might be. Reporting counts and values without an analysis can be transparent as a record of what was posted, while still being insufficient for an inferential conclusion.
The mismatch between broad aims in the study summary and the narrow set of posted outcome results also matters. The summary mentions cholesterol and other metabolic measures, but the registry posts only the bodyweight primary outcome. Readers should distinguish aims described in a protocol summary from outcomes with results available for evaluation. The record does not report secondary results or a multiplicity approach.
Finally, the terminated status underscores the importance of transparent reporting about study completion and analysis. The registry does not state why the study was terminated or provide a statistical plan, missing-data methods, or analysis population. These details would help readers understand the path from randomized assignment to posted results. The case shows why effect estimates, measures of precision, and clear analysis reporting are essential complements to a trial’s design description.
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 most important limitation is the scarcity of outcome information: the record reports a count of 1 in each arm, no spread measure, and no comparative analysis. It gives no confidence interval or test result, so precision cannot be evaluated. The posted values are described as changes in bodyweight, but the sign convention is not stated in the results, restricting interpretation of direction.
The registry is marked terminated, but the reason is not reported in the registry record. It is also not reported whether outcome collection ended as planned, whether the posted arm summaries include all randomized participants, or whether any participants discontinued or had missing measurements. The analysis population and methods for missing data are not reported.
The record does not provide baseline bodyweight or participant characteristics, so the degree of baseline comparability cannot be assessed. Although randomization is listed, the sequence generation and allocation concealment procedures are not reported in the registry record. Masking is described as triple in the design entry and double-blind in the study summary, without an explanation of the difference. Arm descriptions and details of treatment implementation are also absent.
The study summary mentions metabolic outcomes and possible augmentation of antipsychotic effect, but the registry posts no secondary outcome results. The statistical analysis plan, sample-size justification, and multiplicity handling are not reported. The safety data have very small at-risk counts and no event-level details; deaths are not reported in the registry record. Together, these limitations leave the record useful for identifying the study’s stated question and sparse posted outcomes, but inadequate for a firm comparative efficacy or safety assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Treatment on Iatrogenic Weight Gain and Dyslipidaemia Associated With Olanzapine — NCT01491490.
- Registry record last updated 2014-09-18; status last verified 2014-09.
- Results first posted 2013-11-01.
- 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.
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18. Record Summary
The record describes a Phase 2, randomized, parallel-group, placebo-controlled pilot of a 40:1 GWP42003:GWP42004 combination alongside olanzapine. It lists triple masking, while the brief summary describes double-blinding. The planned treatment period was 6 weeks, and the primary endpoint was change in bodyweight from baseline at 6 weeks.
The registry reports enrollment of 2 and an outcome count of 1 in each arm. Primary arm-level values are 3.6 kg for the combination and 1.0 kg for placebo. No comparative analysis, measure of variability, confidence interval, or p-value is posted. The record lists zero serious adverse events in each arm and other adverse events affecting one participant in the combination arm and zero in placebo. Deaths are not reported in the registry record.
The study began in 2011-10, had a primary completion date of 2012-10, and is marked terminated. The reason for termination, analysis plan, analysis population, and missing-data methods are not reported in the registry record.