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 Trial of Quetiapine in Anorexia Nervosa (NCT00518973), a randomized na study. The primary outcome is Hours Occupied by Preoccupations and Rituals Assessed by Yale-Brown-Cornell Eating Disorder Scale (YBC-EDS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00518973 |
| Phase | NA |
| Condition | Anorexia Nervosa |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, San Diego |
| Results posted | Yes |
2. Clinical Question
Population
Men and women aged 18–65 with anorexia nervosa were sought for the study. The registry reports enrollment of 21 participants. It does not report further eligibility details or a fuller description of the participants who entered the trial.
Intervention
The intervention was quetiapine, a drug listed as the experimental treatment. The registry summary describes assessing symptoms related to eating disorders, anxiety, depression and obsessionality, as well as BMI. Dose, treatment duration details beyond the outcome timeframe, and other treatment instructions are not reported in the registry record.
Comparator
The comparison group received placebo. The study is described as randomized, double-blind and parallel, so the intended comparison was between separate groups assigned to quetiapine or placebo. The precise randomization procedure and allocation ratio are not reported in the registry record.
Primary question
The listed primary endpoint measures hours occupied by preoccupations and rituals on the Yale-Brown-Cornell Eating Disorder Scale (YBC-EDS), from Day 1 to last observation carried forward (LOCF), up to 8 weeks. The registry also describes core eating-disorder symptoms assessed with the YBC-EDS and Eating Disorder Inventory-2 (EDI-2). The actual between-group outcome results are not reported in the registry record, so the size and precision of the primary comparison cannot be assessed.
In practical statistical terms, the central question is whether the observed outcome distributions differed between the randomized groups over the stated assessment period. An informative answer would ordinarily include results for each group, an estimate of the between-group contrast, and a measure of its uncertainty. Those numerical primary outcome results are not reported in the registry record. The record therefore identifies what the trial set out to examine, but does not establish how the groups compared on the primary measure.
3. Trial Design
The study is titled “Trial of Quetiapine in Anorexia Nervosa” and is described as a double-blind, placebo-controlled trial. Its design is randomized and parallel: participants were assigned to separate treatment groups rather than crossing between treatments. The interventions are listed as quetiapine and placebo. The sponsor is the University of California, San Diego. The registry lists the study as completed, with enrollment of 21.
The registry lists the study phase as NA. It records a start date of 2006-07 and a primary completion date of 2010-05. These dates describe the recorded study timeline; they do not provide information about the duration of treatment for an individual participant. The primary outcome timeframe is Day 1 to LOCF, up to 8 weeks.
The brief description states that the study sought to assess core eating-disorder symptoms and also anxiety, depression, obsessionality and BMI. The primary endpoint entry specifies hours occupied by preoccupations and rituals on the YBC-EDS. The record’s group descriptions also identify the YBC-EDS and EDI-2 as measures of core eating-disorder symptoms. Secondary outcomes listed include the State-Trait Anxiety Inventory (STAI), the Hamilton Depression Rating Scale (HAM-D), and the Positive and Negative Syndrome Scale (PANNSS). A separate description mentions the Yale-Brown Obsessive Compulsive Scale.
Important design details are not reported in the registry record. These include the random sequence generation and concealment methods, the allocation ratio, treatment dose, adherence procedures, the planned sample-size justification, and the prespecified statistical analysis plan. The record does not report whether interim analyses were planned or conducted. Without those details, the design can be described at the broad level of randomization, masking and parallel groups, but not reconstructed in full.
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: Of these 21, 15 were randomized and began the drug; the other six participants failed the in-person screening phase.
Overall Study
| Stage | Placebo | Quetiapine |
|---|---|---|
| STARTED | 9 | 6 |
| COMPLETED | 6 | 4 |
| NOT COMPLETED | 3 | 2 |
Reasons for not completing this period:
| Reason | Placebo | Quetiapine |
|---|---|---|
| Withdrawal by Subject | 3 | 2 |
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 | Placebo | Quetiapine | Total |
|---|---|---|---|---|
| Participants analysed | 9 | 6 | 15 | |
| Age, Continuous | years | NA (SD NA) | NA (SD NA) | 34 (SD 13.48) |
| Sex: Female, Male: Female | Participants | NA | NA | NA |
| Sex: Female, Male: Male | Participants | NA | NA | NA |
| Region of Enrollment: United States | participants | 9 | 6 | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Hours Occupied by Preoccupations and Rituals Assessed by Yale-Brown-Cornell Eating Disorder Scale (YBC-EDS), measured over Day 1 to LOCF (up to 8 weeks).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Hours |
| Endpoint classification | Continuous Endpoint |
The listed primary endpoint is hours occupied by preoccupations and rituals, assessed with the YBC-EDS. The registry describes the YBC-EDS as an eight-item scale assessing the severity of preoccupations and rituals. Recording hours gives a quantitative measure of the amount of time taken up by these experiences, while the scale supplies a structured assessment framework. The endpoint therefore concerns a specific aspect of eating-disorder symptom burden rather than a global measure of health or functioning.
The outcome is specified as a mean with standard deviation, indicating that the planned summary treats it as a continuous measure. In general, a mean describes the average value in a group, while a standard deviation describes the spread of individual values around that average. Neither statistic alone gives the between-group treatment contrast or its uncertainty.
The recorded timeframe is Day 1 to last observation carried forward (LOCF), up to 8 weeks. The registry does not report the endpoint values for either group, a treatment contrast, or an interval estimating uncertainty. It also does not provide details about the scoring implementation or assessment schedule beyond the stated timeframe. As a result, the measure’s stated purpose can be explained, but the magnitude and precision of the observed comparison cannot be evaluated from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record supports a description of the trial question and design, but not a numerical interpretation of the primary treatment comparison. It identifies a randomized, double-blind, parallel comparison of quetiapine with placebo and specifies hours occupied by preoccupations and rituals on the YBC-EDS as the primary endpoint. However, the primary outcome values and the between-group estimate are not reported in the registry record. There is therefore no basis in the recorded results for describing the direction, size, or statistical precision of that comparison.
The record lists 5 outcome measures and 9 analyses. Those counts indicate that multiple measurements or analyses are registered, but they do not explain which analyses correspond to which outcomes, how they were prioritized, or which estimates were considered confirmatory. The registry describes secondary assessments relating to anxiety, depression and other symptoms. Numerical results for these measures are not reported in the registry record in the registry record for this analysis.
In general, an estimated difference between groups is more informative when reported with a confidence interval. A confidence interval expresses the range of values reasonably compatible with the observed data under the statistical model. Its width indicates precision: a wider interval represents greater uncertainty. A p-value, when reported, addresses how compatible the data are with a specified null hypothesis under the model; it does not measure the size or clinical importance of an effect. No primary comparison estimate, confidence interval or p-value is reported in the registry record, so none can be interpreted.
Enrollment was 21, and the safety entries list 9 participants at risk in the placebo group and 6 in the quetiapine group. These figures do not supply outcome-specific analysis counts or explain the difference between the total enrollment and the safety group counts. The analysis populations and participant flow are not reported in the registry record. The outcome denominators, missingness patterns and handling of incomplete outcome assessments are also not reported, apart from the endpoint timeframe’s reference to LOCF.
Consequently, the registry record cannot establish whether any observed difference was large or small, precise or uncertain, or consistent across outcomes. Nor does the absence of numerical outcome results show that the groups were equivalent. A conclusion of similarity requires estimates precise enough to rule out differences of relevant size; such estimates are not reported. The appropriate reading is limited: the trial was registered as a randomized comparison with specified symptom measures, while the outcome results needed to interpret its treatment contrast are not reported in the registry record.
9. Statistical Methods Explained
Randomization is intended to make treatment assignment independent of participant characteristics, on average, so that a comparison between groups can be interpreted as a treatment contrast rather than simply a comparison of initially different kinds of participants. In a small trial, random assignment does not guarantee that all important characteristics are balanced. The registry identifies the study as randomized but does not report how the sequence was generated, whether assignment was concealed before enrollment, or what allocation ratio was used. Those details matter when assessing the protection against selection bias.
Double masking means that the study is described as keeping treatment identity concealed from two groups of people involved in the trial. The registry does not specify exactly who was masked or how masking was maintained. Placebo is the comparator, and the parallel design means participants were assigned to one group rather than receiving both interventions in sequence. In general, a placebo comparison can help separate differences associated with assignment to the study drug from differences associated with receiving an intervention and being assessed. The details of the placebo and the treatment procedures are not reported in the registry record.
The primary measure is continuous: hours occupied by preoccupations and rituals on the YBC-EDS. The endpoint entry specifies a mean and standard deviation. In general, a mean is a measure of the center of a distribution, and a standard deviation describes variability among observations. A group mean alone does not indicate how much the group differs from another. The main comparative quantity would usually be a between-group estimate, interpreted alongside its uncertainty. The registry record does not report the group means, standard deviations, or a primary contrast.
In general, a confidence interval helps communicate uncertainty around an estimated contrast. It reflects the data and the assumptions of the analysis, and its width is informative about precision. A narrow interval indicates a more precise estimate than a wide interval, though neither width nor statistical significance by itself determines clinical importance. A p-value is a measure of compatibility between the observed data and a specified null model, given the analysis assumptions. It is not the probability that the null hypothesis is true, nor is it an effect-size measure. No confidence interval or p-value for the primary outcome is reported in the registry record.
What does the endpoint timeframe mean?
The endpoint is recorded from Day 1 to LOCF, up to 8 weeks. LOCF stands for last observation carried forward. In general, this approach uses a participant’s last recorded measurement as a substitute for a later measurement that is missing. It relies on assumptions about what the unobserved later value would have been. Those assumptions can be problematic if outcomes change over time, and LOCF does not remove uncertainty caused by missing data. The registry record does not describe how many observations were missing, why they were missing, or whether additional methods were used to assess the effect of missingness.
Why does multiplicity matter?
When researchers examine several outcomes or conduct several analyses, the chance of obtaining at least one apparently unusual result can increase if every test is treated as independent and interpreted without adjustment. This general issue is called multiplicity. The registry lists 5 outcome measures and 9 analyses, but does not report a multiplicity adjustment, a hierarchy of outcomes, or the statistical plan defining which comparisons were primary or secondary. The number of registered analyses alone does not show whether adjustment was necessary or used; the analysis plan and outcome structure would be needed to assess that question.
What would over-dispersion mean?
Over-dispersion is a general issue for count outcomes when the observed variation exceeds what an assumed probability model expects. In such settings, standard errors can be too small if the extra variation is ignored. The listed primary endpoint is a continuous measure summarized by a mean and standard deviation, not a count endpoint, so the registry entries do not establish that over-dispersion is relevant to the primary analysis. The statistical model used is not reported in the registry record.
Sample-size planning and observed results answer different questions. In general, a planning calculation describes what group size might be needed under specified assumptions about the effect, variability and analysis. It is not a measure of the power actually achieved after a study has been completed. The registry record does not report a trial-specific sample-size justification or the assumptions used to plan enrollment. No planning illustration can substitute for an observed effect estimate and its uncertainty.
Finally, analysis populations affect how participants are included in the comparison. For example, an analysis might follow assigned groups, or might include only participants meeting specified adherence or assessment criteria. These are general approaches; the registry record does not identify the analysis population used for the primary endpoint. Without that information, the handling of participants who discontinued, missed assessments, or lacked usable outcome data cannot be assessed.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 5 outcome measures and 9 analyses. It identifies a primary endpoint and describes additional symptom measures, but the record does not report the statistical plan, a prespecified hierarchy among outcomes, or whether any correction for multiple comparisons was used. These omissions matter because assessing several outcomes or contrasts can increase the chance that at least one result appears noteworthy by chance. Whether and how that concern applies depends on the planned hypotheses and analysis structure, which are not reported in the registry record.
The primary endpoint timeframe is Day 1 to LOCF, up to 8 weeks. LOCF generally refers to carrying a participant’s last recorded value forward when a later observation is absent. The record does not report the number of missing observations, reasons for missingness, timing of missing assessments, or sensitivity analyses. It is therefore not possible to judge how incomplete follow-up may have affected the primary comparison.
The registry record does not report the primary analysis population, participant flow by group, or whether the comparison followed randomized assignment. It also does not report how protocol deviations or participants without endpoint measurements were handled. Enrollment is listed as 21, while the serious-event entries list 9 at risk in the placebo group and 6 in the quetiapine group. Those safety figures do not establish the analysis denominators for the efficacy outcomes.
These gaps limit reproducibility and make it difficult to determine whether the reported analyses, if any, followed the intended plan. Numerical outcome results and analysis details are not reported in the registry record.
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 |
|---|---|---|---|
| Placebo | 1 | 9 | 11.1% |
| Quetiapine | 2 | 6 | 33.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Placebo | 0 of 9 |
| Quetiapine | 0 of 6 |
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 |
|---|---|
| Placebo | 0 of 9 |
| Quetiapine | 0 of 6 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | Quetiapine |
|---|---|---|---|
| Worsening weight loss | Metabolism and nutrition disorders | 0 of 9 | 1 of 6 |
| Car Accident | Social circumstances | 0 of 9 | 1 of 6 |
| Worsening Manic Symptoms | Psychiatric disorders | 1 of 9 | 0 of 6 |
Serious events with the highest arm-level rate: worsening weight loss (16.7%), car accident (16.7%), worsening manic symptoms (11.1%).
The safety entries list serious adverse events for the placebo group, with 9 participants at risk and 1 affected, and for the quetiapine group, with 6 at risk and 2 affected. Deaths are listed as 0 in both groups. Other adverse events are listed as 0 affected among 9 at risk in the placebo group and 0 affected among 6 at risk in the quetiapine group.
The registry also lists serious-event terms with percentages: Worsening weight loss, 16.7%; Car Accident, 16.7%; and Worsening Manic Symptoms, 11.1%. The record does not identify the group associated with each of these terms in the registry record, so they should not be assigned to a treatment group. It also does not provide further event descriptions, timing, duration, or an assessment of relatedness to treatment.
In general, adverse-event counts describe events recorded during a study; they do not by themselves establish that an intervention caused an event. Small group counts can also make safety comparisons imprecise. The safety figures should be read as registry entries, not as a complete assessment of comparative risk. The participant denominators and event counts above are distinct from the missing efficacy results; the registry record does not report the primary outcome comparison.
12. What the Result Does, and Does Not, Mean
The available registry information establishes that this was a randomized, double-blind, placebo-controlled, parallel trial of quetiapine in anorexia nervosa, with enrollment of 21. It identifies a primary measure focused on hours occupied by preoccupations and rituals on the YBC-EDS, assessed from Day 1 to LOCF, up to 8 weeks. It also describes intended assessments of other eating-disorder symptoms and secondary symptoms.
What the registry information does not establish is the observed difference between the quetiapine and placebo groups on the primary endpoint. The group outcome values, between-group estimate, confidence interval and p-value are not reported in the registry record. The same limitation applies to interpreting the listed secondary outcome measures: their numerical results are not reported in the registry record. Without those results, it is not possible to describe the direction, size or precision of any outcome contrast.
In general, a study’s design and outcome definitions explain what it was intended to test, while its results show what was observed. A missing result is not evidence that there was no difference. Likewise, a small or large sample alone does not establish whether an effect is present or absent. The estimate and its uncertainty are needed to distinguish an imprecise result from a precise estimate near no difference.
The safety entries record serious adverse events and deaths by group, but do not provide enough contextual detail for a comprehensive comparison of safety. Event counts do not establish causation, and the registry does not report group attribution for the listed serious-event terms in the registry record. The efficacy and safety information therefore answer different questions and should not be conflated.
The cautious conclusion is that the registry record documents a clinical trial question, broad design features, outcome definitions and selected safety counts. It does not report the outcome results necessary to conclude whether the groups differed, or by how much. No treatment recommendation follows from these incomplete results.
13. Why This Trial Matters Statistically
This trial illustrates why a registered research question and a reported treatment effect are not the same thing. The registry identifies a randomized, double-blind comparison and defines a symptom-focused primary endpoint. Those features allow readers to understand the broad intended comparison. But without the group results and an estimate of the contrast, the effect and its precision cannot be evaluated statistically.
The distinction is especially important for small trials. Enrollment is listed as 21, while the safety entries list 9 participants at risk in the placebo group and 6 in the quetiapine group. Small amounts of information can leave estimates uncertain, but the degree of uncertainty must be assessed from the actual results and their interval estimates. Those are not reported in the registry record. It would be inappropriate to infer an effect, or a lack of effect, from enrollment alone.
The record also lists multiple outcomes and analyses. This highlights a common statistical issue: decisions about which outcomes are primary, how secondary outcomes are interpreted, and whether multiplicity is addressed should be transparent. Here, the outcome and analysis counts are recorded, but the relevant analysis plan and multiplicity approach are not reported in the registry record. Counts alone are not enough to determine how results should be interpreted.
Finally, reference to LOCF makes missing-data methods relevant to interpretation. The method’s use is indicated in the endpoint timeframe, but the extent of missingness and any sensitivity analyses are not reported. Transparent reporting of participant flow, analysis populations, missingness, and outcome estimates would help readers judge the robustness of a clinical trial comparison. The record’s limitations demonstrate why statistical interpretation depends on more than a trial title, design label, or list of outcome measures.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Several trial-specific details needed for a full assessment are not reported in the registry record. These include the randomization procedure, allocation concealment, allocation ratio, treatment dose, and the exact roles covered by double masking. The record describes the study as randomized and double-blind, but those labels alone do not permit assessment of how well assignment and masking were implemented.
The listed primary endpoint is hours occupied by preoccupations and rituals on the YBC-EDS, while the group descriptions also refer to the YBC-EDS and EDI-2 as measures of core eating-disorder symptoms. The registry does not explain the relationship between these descriptions or report a detailed hierarchy among the outcome measures. Although it lists 5 outcome measures and 9 analyses, it does not report a statistical analysis plan, multiplicity approach, or the specific analyses corresponding to those counts.
The primary outcome results, including group summaries and a between-group estimate, are not reported in the registry record. Results for the listed secondary outcomes are also not reported in the registry record. This prevents assessment of effect size, uncertainty, and consistency across measures. Enrollment is 21, but the safety groups list 9 at risk in placebo and 6 in quetiapine; participant flow and the analysis denominators for efficacy outcomes are not reported.
The endpoint timeframe refers to LOCF, but the registry does not report the amount or pattern of missing data, reasons for missing assessments, or sensitivity analyses. It also does not report the primary analysis population or how deviations from the assigned treatment were handled. The sample-size justification and any interim analyses are not reported in the registry record. These limitations constrain both interpretation and reproducibility.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Trial of Quetiapine in Anorexia Nervosa — NCT00518973.
- Registry record last updated 2019-07-17; status last verified 2019-06.
- Results first posted 2019-07-17.
- 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 NCT00518973 as a completed randomized, double-blind, parallel, placebo-controlled trial of quetiapine in anorexia nervosa, sponsored by the University of California, San Diego. Enrollment is listed as 21, and the study phase is recorded as NA. The primary endpoint is hours occupied by preoccupations and rituals assessed with the YBC-EDS from Day 1 to LOCF, up to 8 weeks.
The record describes additional assessments related to eating-disorder symptoms, anxiety, depression and other symptoms. Safety entries list 1 serious adverse event among 9 at risk in placebo and 2 among 6 at risk in quetiapine, with 0 deaths in each group. Primary and secondary outcome results, statistical analysis details, and the sample-size justification are not reported in the registry record. The record therefore defines the trial’s broad question and selected safety counts, but does not permit evaluation of the efficacy comparison’s magnitude or precision.