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 Drug Treatment for Pathologic Gambling Disorder (NCT00053677), a randomized phase 3 study. The primary outcome is Yale-Brown Obsessive Compulsive Scale for Pathological Gambling (PG-YBOCS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00053677 |
| Phase | Phase 3 |
| Condition | Gambling |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 83 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Chicago |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns patients with Pathological Gambling Disorder (PGD) and severe urge symptoms, as described in the brief summary. The registry record does not report detailed eligibility criteria or a fuller description of the population included in the primary-outcome analysis.
Intervention
Participants assigned to active treatment received naltrexone in a 17-week double-blind phase. The arm description lists naltrexone 50mg/day, 100mg/day, and 150mg/day conditions. It also says treatment began at 25mg/day for two days to minimize nausea, but the rest of that dose-escalation description is truncated in the registry record.
Comparator
The comparator was placebo during the 17-week double-blind phase. The registry record describes random assignment to placebo or to one of the naltrexone dose conditions. It does not report a numerical primary-outcome comparison between placebo and any naltrexone condition.
Primary question
The primary measure was the Yale-Brown Obsessive Compulsive Scale for Pathological Gambling (PG-YBOCS), described as a measure of gambling urges and thoughts. The clinical question is whether scores at the stated 18-week timeframe differed across treatment assignments. The registry record does not report the group scores, treatment-effect estimate, confidence interval, or statistical test for that question.
3. Trial Design
The registry classifies this as a Phase 3 randomized, triple-masked, parallel study. It lists University of Chicago as the sponsor, Gambling as the condition, an enrollment of 83, and a completed status. The recorded start is 2002-12, and primary completion is 2005-11. These registry fields describe the study record; they do not provide a primary efficacy result.
The interventions are naltrexone and placebo. The naltrexone arm description identifies a 17-week double-blind phase and lists three dose conditions: 50mg/day, 100mg/day, and 150mg/day. It says that treatment for all subjects began at 25mg/day for two days to minimize nausea, but the remaining dose instructions are cut off. The placebo description identifies participants assigned to placebo in the same 17-week phase. The record does not report the number assigned to each naltrexone dose condition or a complete account of how those conditions were compared in the analysis.
Triple masking is the registry's recorded masking classification; the record does not name the masked roles or explain how masking was maintained. Likewise, randomization is recorded, but details of sequence generation, concealment, stratification, or block size are not reported in the registry record. The parallel model indicates that the assigned groups were followed as separate treatment groups rather than described as a crossover. The record does not give enough information to reconstruct the conduct of the allocation process or determine whether all randomized participants were included in the analysis.
Although the study is marked completed, completion status is not evidence that a result was posted. The primary outcome description gives an 18-week timeframe and a last-visit scoring rule. However, the outcome data do not supply a single comparison, and the analysis count is recorded as zero. Consequently, the design can be described, but the primary treatment contrast and its statistical uncertainty cannot be evaluated from 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: 83 participants began the placebo lead-in phase. 6 of those were placebo responders. The remaining 77 were randomized to Naltrexone or placebo.
Overall Study
| Stage | Naltrexone | Placebo |
|---|---|---|
| STARTED | 58 | 19 |
| COMPLETED | 36 | 13 |
| NOT COMPLETED | 22 | 6 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Naltrexone | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 58 | 19 | 77 | |
| Age, Continuous | Years | 47.8 (SD 9.65) | 44.7 (SD 9.67) | 46.3 (SD 9.66) |
| Sex: Female, Male: Female | Participants | 37 | 10 | 47 |
| Sex: Female, Male: Male | Participants | 21 | 9 | 30 |
| Race/Ethnicity, Customized: Race/Ethnicity – White | Participants | 54 | 16 | 70 |
| Race/Ethnicity, Customized: Race/Ethnicity – Other Race | Participants | 4 | 3 | 7 |
| Region of Enrollment: United States | participants | 58 | 19 | 77 |
6. Primary Endpoint
The registry lists the primary outcome as Yale-Brown Obsessive Compulsive Scale for Pathological Gambling (PG-YBOCS), measured over 18 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the Yale-Brown Obsessive Compulsive Scale for Pathological Gambling (PG-YBOCS), a measure derived from the Yale-Brown Obsessive Compulsive Scale. The record says that it sums questions about gambling urges and thoughts into a total score. Scores range from 0 to 40, with higher scores indicating more severe gambling symptoms and therefore a worse outcome on this measure.
The endpoint is intended to quantify symptom severity rather than simply record whether gambling occurred. A scale score can represent gradations in the reported symptoms, which may help describe changes in severity across treatment groups. That is the general rationale for using a continuous outcome: it retains information about score levels instead of reducing every participant's experience to a yes-or-no category. The registry record does not describe validation properties or establish how a score change should be interpreted clinically.
The stated timeframe is 18 weeks. The measure was administered every week for the first 8 weeks and every other week for the remaining 10 weeks. The final-visit value was defined as the score measured at each participant's last visit; earlier scores were not combined to calculate that value. This makes the endpoint a last-visit score rather than a summary of all repeated measurements. The record does not report the group means, standard deviations, participant counts contributing scores, or an estimated difference at this timeframe. It therefore describes what was intended to be measured, but not the observed primary outcome contrast.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the broad question and study structure: randomized assignment to naltrexone dose conditions or placebo, with PG-YBOCS as the primary measure. It does not establish what the primary outcome showed. No group means, standard deviations, treatment-effect estimate, confidence interval, or primary-outcome test are reported. Without these quantities, readers cannot determine the direction or size of a difference in scores, or how precisely any difference was estimated.
The endpoint's scoring direction matters when interpreting any future result: higher PG-YBOCS scores indicate more severe gambling symptoms. That describes the scale, not the outcome of this trial. Since the registry record contains no group results, it would be inappropriate to infer whether scores were higher or lower in either assignment, or whether any observed difference was large or small.
The measure was assessed repeatedly, but the listed final-visit score uses each participant's last recorded visit and does not combine earlier measurements. This rule is relevant because a last-visit summary and a repeated-measures analysis answer different statistical questions. A last-visit comparison uses the designated endpoint value; a repeated-measures analysis would use the pattern across visits. The registry record does not report a fitted longitudinal analysis or a primary contrast derived from repeated observations.
The study is marked completed, yet the record lists zero analyses and signals that the primary outcome has several categories or time points and was not reduced to one comparison. Thus, the absence of an interpretable result is not evidence of no effect, nor is it evidence of an effect. It is an absence of a posted numerical comparison in the registry record. Any conclusion about efficacy, dose response, or statistical significance would require results not reported in the registry record.
Precision also cannot be judged. A confidence interval would show a range of effect estimates compatible with the data under the analysis assumptions; its width would help distinguish a precise estimate from one with substantial uncertainty. No such interval is reported. A p-value alone would not describe the magnitude or precision of an effect, and none is reported for the primary outcome in any case. The available information supports description of the endpoint and design, but not a statistical conclusion about the treatment contrast.
9. Statistical Methods Explained
The recorded study design is randomized and parallel, with triple masking. In general, randomization is used to make assigned groups comparable in expectation with respect to measured and unmeasured characteristics. It does not guarantee exact balance in a particular trial. Masking is intended to limit the influence of treatment knowledge on conduct, assessment, or interpretation, depending on which roles are masked. The registry record does not specify which roles were masked, how allocation was generated or concealed, or how masking was assessed. These procedural details are not reported in the registry record.
A parallel design compares groups assigned to different interventions over the study period. In this case the record names naltrexone and placebo, and describes three naltrexone dose conditions. The registry record does not state the exact primary comparison used for analysis, such as whether each dose was compared separately with placebo, whether doses were combined, or whether there was a prespecified trend test. These are different estimands and could lead to different interpretations. No choice among them can be inferred from the intervention descriptions alone.
The endpoint is continuous and is summarized by a mean with standard deviation according to its recorded outcome type. The mean describes the central level of scores, while the standard deviation describes variation among individual scores around that mean. In general, comparing group means estimates an average difference on the scale. The standard deviation is not the uncertainty of the estimated mean difference; that uncertainty also depends on the amount and structure of available data and on the analysis model. The registry record does not provide the group summaries or an estimate of the difference.
A confidence interval is a general way to express statistical uncertainty around an estimate. It gives a range of values compatible with the data and specified model under repeated use of the method. A narrow interval indicates greater precision than a wide interval, but interpretation also depends on the scale and the meaningful size of effects. No confidence interval for PG-YBOCS is reported in the registry record. Without an estimate and interval, neither the size nor precision of the primary comparison can be assessed.
The scale was measured repeatedly, but the outcome description defines the endpoint as the score at the last visit for each participant. The description says prior visit scores were not combined to compute that value. In general, a last-visit analysis can be straightforward to describe, but it does not use the full trajectory in the way a repeated-measures model does. It can also depend on which participants have an observed last-visit score and when their last visit occurred. The record does not report a longitudinal model, an adjustment for baseline score, or the precise analysis population.
The record's outcome note says the primary outcome has several categories or time points and was not reduced to one comparison. That leaves the inferential target unclear. Multiple doses, possible contrasts, and repeated assessments can create multiplicity: when several hypotheses are tested, the chance of at least one apparently unusual result can increase if each is assessed without accounting for the family of tests. This is a general statistical concern, not a claim that a particular adjustment was or was not performed in this trial. The registry record does not report a multiplicity strategy, primary contrast hierarchy, or statistical analysis plan.
Over-dispersion is a general concern when observed variation exceeds what a chosen statistical model assumes. For a continuous score, analysts would examine whether the distributional and variance assumptions are reasonable for the intended model. The record reports that the measure is continuous and that its dispersion is standard deviation, but does not report diagnostic checks, transformation, robust variance methods, or a model addressing over-dispersion. No distributional assumption can therefore be attributed to the trial analysis.
The sample-size assumptions describe a planning illustration, not the trial's design justification: two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. Such illustrations ask how many participants per arm might be needed under those assumptions. They are not observed power, and they do not establish the trial's original sample-size rationale. The registry record does not report the protocol's sample-size justification or a numerical planning result that can be interpreted as the study's own design calculation.
The analysis count is recorded as zero, and no numerical primary-outcome analysis is posted. Consequently, there is no reported test statistic, p-value, model coefficient, standard error, or confidence interval to interpret. The statistical methods underlying a primary efficacy estimate are not reported in the registry record. General explanations of these methods should not be mistaken for a description of analyses actually carried out in this study.
10. Multiplicity, Missing Data and Analysis Populations
The endpoint description includes repeated assessments and the study includes multiple naltrexone dose conditions. Those features raise general questions about which time point and treatment contrasts were designated as primary, and whether any adjustment or hierarchy was used to control multiplicity. The registry record flags that the primary outcome has several categories or time points and was not reduced to one comparison. It does not report a prespecified testing hierarchy, adjustment method, or analysis plan. Without those details, the intended family of statistical tests cannot be reconstructed.
Missing-data handling is also not reported in the registry record. The outcome rule selects each participant's score at the last visit, but it does not say how a participant with no recorded score, an early last visit, or an incomplete assessment was handled. The record does not report the number of missing scores, reasons for missingness, imputation methods, sensitivity analyses, or whether the analysis used all randomized participants. The enrollment field alone does not identify the analysis population or the number contributing outcome data.
These omissions matter because conclusions from a last-visit comparison may depend on which scores are available and on assumptions about missing observations. In general, imputation or model-based approaches require assumptions about the missing-data process, while complete-case analysis uses only participants with observed data for the analysis. The registry record does not identify an approach, so neither method should be attributed to the trial. It also does not report an intention-to-treat definition or a per-protocol population. The posted information therefore does not support assessing how missingness or multiplicity may have affected the primary inference.
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 |
|---|---|---|---|
| Naltrexone | 0 | 58 | 0.0% |
| Placebo | 0 | 19 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Naltrexone | 50 of 58 |
| Placebo | 17 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Naltrexone | Placebo |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 35 of 58 | 7 of 19 |
| Headache | Nervous system disorders | 23 of 58 | 9 of 19 |
| Diarrhea | Gastrointestinal disorders | 8 of 58 | 6 of 19 |
| Dry Mouth | General disorders | 8 of 58 | 2 of 19 |
| Dizziness | General disorders | 6 of 58 | 1 of 19 |
| Insomnia | Nervous system disorders | 7 of 58 | 0 of 19 |
| Constipation | Gastrointestinal disorders | 3 of 58 | 3 of 19 |
The registry safety fields list serious adverse events affecting 0 participants among 58 at risk in the naltrexone group, and 0 among 19 at risk in the placebo group. These are recorded counts, not evidence that no adverse events of any kind occurred. The record also lists other adverse events affecting 50 participants among 58 at risk in the naltrexone group and 17 among 19 at risk in the placebo group. No percentages or comparative safety estimate are reported, and none should be inferred from the counts alone.
The deaths field is null for both groups, so death counts are not reported in the registry record. The record does not provide serious-event terms, and it does not give event descriptions, severity, timing, attribution, or a statistical comparison. The listed group counts do not establish whether events were related to treatment. They also do not provide enough information to compare risks while accounting for differences in exposure or follow-up. These entries should therefore be read as the registry's reported safety counts, not as a complete account of safety or as a causal estimate.
12. What the Result Does, and Does Not, Mean
The record supports several descriptive statements: the study was randomized, triple-masked, and parallel; it was marked completed; and its primary endpoint was a continuous PG-YBOCS score at an 18-week timeframe. The score reflects gambling urges and thoughts, with higher values indicating more severe symptoms. Naltrexone and placebo were the named interventions, and the naltrexone arm description included several dose conditions.
Those design details do not establish the treatment result. The registry record does not report outcome means, standard deviations, an effect estimate, a confidence interval, or a primary-outcome test. It is therefore not possible to state from this record whether the groups differed, how large any difference was, or how precisely it was estimated. The absence of a posted result should not be interpreted as a finding of no difference, and it cannot support a claim that treatment did or did not work.
The endpoint's schedule and last-visit rule also limit what can be inferred from its description alone. Repeated measurement does not mean that all scores were combined in the primary analysis; the record explicitly says earlier scores were not combined to calculate the final-visit value. Nor does the score range explain what magnitude of change would be clinically important. That threshold is not reported in the registry record.
Finally, a completed status and an enrollment figure do not reveal how many participants contributed to the endpoint analysis, how missing data were handled, or which treatment contrast was tested. Without those elements, statistical significance, clinical relevance, dose response, and the robustness of any result remain unassessable from the registry record. The most defensible interpretation is that the trial's design and intended measurement are described, while its primary comparative result is not reported.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of why a design description and an outcome result are not interchangeable. Randomization, masking, and a defined symptom scale describe how a study was structured and what it sought to measure. They do not, on their own, reveal the observed difference between assigned groups or the uncertainty around that difference. A completed registry status likewise does not substitute for a posted analysis.
The primary measure also illustrates the distinction between collecting repeated observations and defining a single endpoint. PG-YBOCS was administered on a schedule spanning the stated 18-week timeframe, but the recorded final value was the participant's last-visit score, without combining prior scores. Analyses of a final score and analyses of a trajectory use information differently and answer different questions. Clear reporting of the chosen estimand and analysis is needed to understand which question a result addresses.
Multiple dose conditions create an additional reporting need: readers need to know which contrasts were prespecified and how multiple comparisons were handled. This is a general statistical issue, not evidence that the study used an inappropriate method. Because the record does not report a testing hierarchy or primary comparison, a reader cannot identify the inferential target for the outcome.
Finally, complete reporting requires more than a statement of study completion. Group summaries, an effect estimate, uncertainty, analysis populations, and missing-data methods are needed to evaluate the primary finding. Their absence means that readers can understand the intended design and endpoint but cannot assess the efficacy estimate or its precision. That distinction is central to responsible interpretation of clinical-trial registry records.
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 main trial-specific limitation for statistical interpretation is that the registry record does not provide a single primary-outcome comparison. It reports the PG-YBOCS measure and its timing but no group means, standard deviations, treatment-effect estimate, confidence interval, or test. Its note that the outcome has several categories or time points and was not reduced to one comparison prevents a clear account of the primary inferential result.
The naltrexone description lists 50mg/day, 100mg/day, and 150mg/day conditions, but the record does not report the allocation to each condition or clarify which dose contrasts were analyzed. The dose-escalation instructions are truncated after the description of starting at 25mg/day for two days. Masking is recorded as triple, but the masked roles and masking procedures are not described. Randomization procedures and the statistical analysis plan are also not reported in the registry record.
The endpoint description defines a last-visit score, yet the record does not explain how missing scores or early last visits were handled. It does not state the analysis population, report attrition by group, or describe sensitivity analyses. The repeated assessment schedule is available, but no longitudinal analysis is reported. These gaps prevent assessment of the influence of missing data or the relationship between the final-visit endpoint and the full measurement trajectory.
The safety entries provide counts but not event terms or exposure-adjusted comparisons. Death counts are not reported in the registry record. More broadly, detailed eligibility criteria and a clinically meaningful threshold for interpreting PG-YBOCS changes are not reported. These limitations do not establish that the study was conducted improperly; they define what cannot be assessed from the posted registry information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Drug Treatment for Pathologic Gambling Disorder — NCT00053677.
- Registry record last updated 2023-02-23; status last verified 2023-02.
- Results first posted 2017-10-03.
- 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 a completed, randomized, triple-masked, parallel Phase 3 study sponsored by University of Chicago, with an enrollment of 83. It lists naltrexone and placebo as interventions and describes several naltrexone dose conditions in a 17-week double-blind phase. The primary endpoint is the PG-YBOCS score at an 18-week timeframe, with higher scores indicating more severe gambling symptoms.
The registry record does not report a primary-outcome comparison or analysis, and it flags that the outcome was not reduced to one comparison. It therefore does not provide a treatment-effect estimate or its precision. Safety entries list serious and other adverse-event counts; death counts are not reported in the registry record. The study's design and intended outcome are documented, but the primary efficacy result cannot be interpreted from the posted record.