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 To Evaluate if the Medication Gabapentin Lessens Vulvar Pain (NCT00390013), a randomized na study. The primary outcome is Change From Baseline in Vulvar Pain.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00390013 |
| Phase | NA |
| Condition | Vulvar Pain Symptoms, Vulvodynia (Chronic Vulvar Pain) |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Triple |
| Enrollment | 9 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Colleen Stockdale |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerned women experiencing vulvar pain symptoms, including vulvodynia (chronic vulvar pain). The registry says recruitment was poor and the study terminated early. It does not report detailed eligibility criteria or describe the characteristics of the participants who contributed to the posted outcome.
Intervention
The active treatment was gabapentin, described as titration and dosing for a total of 8 weeks in a crossover design. The clinical question was whether gabapentin lessened vulvar pain. The registry does not provide further detail about dose levels or how participants’ treatment sequences were assigned.
Comparator
The comparator was a placebo oral capsule, also described as titration and dosing for a total of 8 weeks in the crossover design. The trial was randomized and triple masked. The record does not specify which people were masked or give additional details about the masking procedures.
Primary question
The primary outcome was change from baseline in vulvar pain, assessed on an ordinal scale from 0-10, where 0 meant no pain and 10 meant the most severe pain. The outcome description names assessments at the end of the first treatment, after 8 weeks, and at the end of the second treatment, after 19 weeks. The listed primary timeframe is 19 weeks. The registry reports arm-level means and full ranges, but no statistical analysis comparing gabapentin with placebo.
3. Trial Design
The registry describes a randomized, triple-masked crossover pilot study of gabapentin and placebo. In a crossover design, treatment conditions are arranged across periods rather than assigned only as parallel treatments. In general, this can allow comparisons within the same participant, but interpretation depends on the treatment sequence, period effects, and the analysis used. The registry record does not report those details, so it is not possible to determine how the crossover was implemented or analyzed.
Gabapentin was described as titration and dosing for a total of 8 weeks, and the placebo oral capsule was described on the same basis. The primary outcome description identifies an assessment at the end of the first treatment after 8 weeks and another at the end of the second treatment after 19 weeks. The record does not explain the timing between periods or whether any other design features were used to address carryover effects.
The enrollment was 9. The posted arm-level outcome summaries list 6 for gabapentin and 6 for placebo. Because the study is described as crossover, those arm counts should not be added or treated as a count of distinct participants. The record does not explain why the outcome counts differ from the enrollment or identify the analysis population.
The trial began in 2007-01, had a primary completion date of 2008-03, and is recorded as terminated. The registry attributes early termination to poor recruitment. It does not report a target enrollment, recruitment plan, or the reason the study was stopped beyond that explanation.
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: Study has 2 phases: first was a placebo controlled randomized study (4 participants) second was a cross-over study (5 participants - 2 did not cross over)
Phase 1
| Stage | Gabapentin First Then Placebo Crossover | Placebo Oral Capsule First Then Gabapentin Crossover | Treatment Only (Gabapentin) | Placebo Control Arm |
|---|---|---|---|---|
| STARTED | 0 | 0 | 2 | 2 |
| COMPLETED | 0 | 0 | 2 | 1 |
| NOT COMPLETED | 0 | 0 | 0 | 1 |
Reasons for not completing this period:
| Reason | Gabapentin First Then Placebo Crossover | Placebo Oral Capsule First Then Gabapentin Crossover | Treatment Only (Gabapentin) | Placebo Control Arm |
|---|---|---|---|---|
| tired | 0 | 0 | 0 | 1 |
Phase 2 First Treatment
| Stage | Gabapentin First Then Placebo Crossover | Placebo Oral Capsule First Then Gabapentin Crossover | Treatment Only (Gabapentin) | Placebo Control Arm |
|---|---|---|---|---|
| STARTED | 3 | 2 | 0 | 0 |
| COMPLETED | 2 | 1 | 0 | 0 |
| NOT COMPLETED | 1 | 1 | 0 | 0 |
Reasons for not completing this period:
| Reason | Gabapentin First Then Placebo Crossover | Placebo Oral Capsule First Then Gabapentin Crossover | Treatment Only (Gabapentin) | Placebo Control Arm |
|---|---|---|---|---|
| tired | 1 | 0 | 0 | 0 |
| Withdrawal by Subject | 0 | 1 | 0 | 0 |
Phase 2 Second Treatment
| Stage | Gabapentin First Then Placebo Crossover | Placebo Oral Capsule First Then Gabapentin Crossover | Treatment Only (Gabapentin) | Placebo Control Arm |
|---|---|---|---|---|
| STARTED | 2 | 1 | 0 | 0 |
| COMPLETED | 2 | 1 | 0 | 0 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: study terminated early due to poor recruitment
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 | All Cross Over Participants | Gabapentin (Phase 1) | Placebo (Phase 1) | Total |
|---|---|---|---|---|---|
| Participants analysed | 5 | 2 | 2 | 9 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 5 | 2 | 2 | 9 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 5 | 2 | 2 | 9 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 5 | 2 | 2 | 9 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 5 | 2 | 2 | 9 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in Vulvar Pain, measured over 19 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | units on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was change from baseline in vulvar pain. Pain was assessed using an ordinal scale from 0-10, with 0 defined as no pain and 10 as the most severe pain. The registry describes the outcome as the mean change and reports the full range of observed values for each treatment arm.
Change from baseline is used to describe how an outcome differs from its starting measurement over a specified period. In general, a pain scale gives a structured way to record participants’ reported pain, while a change score expresses the shift relative to baseline. On a scale where higher values indicate more severe pain, a negative change would ordinarily correspond to a lower score; however, the registry record does not state the subtraction convention used to calculate change. The signed values should therefore be read as posted, without assuming an unstated convention.
The registry lists a primary timeframe of 19 weeks. Its outcome description also refers to the end of the first treatment after 8 weeks and the end of the second treatment after 19 weeks. It does not clarify which assessment the posted arm summaries represent or how the assessments were combined. That uncertainty matters when interpreting the endpoint because the summary values cannot be confidently assigned to a particular treatment period from the record alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted mean change is -1.3 for gabapentin and -1.3 for placebo. The reported full range is -6.0 to 0.0 for gabapentin and -5.0 to 0.0 for placebo. These are arm-level summaries, not an estimate of the treatment contrast. Although the two listed means are the same, the registry does not report a direct comparison, uncertainty interval, or hypothesis test. The arm summaries alone therefore do not establish whether the treatments differed.
The ranges describe the spread from the lowest to the highest observed changes in each arm. They are not confidence intervals and do not show the precision of an estimated treatment effect. Both ranges include 0.0, but the record does not provide participant-level values or enough detail to determine how changes were distributed within either arm. The posted summaries also do not explain whether the endpoint values refer to the first treatment assessment or the assessment at the end of the second treatment.
The registry identifies a crossover design, in which a treatment comparison may use information from measurements made under both conditions for the same participant. A comparison appropriate to that design would need to account for the paired structure and potentially for treatment period or sequence. No such analysis is reported. The listed arm means and ranges cannot substitute for a within-participant contrast, and no recalculated comparison is available in the registry record.
The record reports 9 enrolled and an outcome count of 6 in each treatment arm. Those figures do not, by themselves, show how many people completed both periods or contributed to a paired analysis. No analysis population, missing-data approach, or reason for the difference between enrollment and the arm-level outcome counts is reported.
Early termination due to poor recruitment limits how much can be learned from the posted outcome. The registry does not report a completed statistical analysis, and the trial’s status is terminated. The results are best read as descriptive summaries from a small pilot trial, not as a definitive estimate of the effect of gabapentin relative to placebo. The record does not provide enough information to judge the precision of a treatment comparison or to draw conclusions beyond the posted arm-level observations.
9. Statistical Methods Explained
The registry identifies randomization, triple masking, and a crossover model. These labels describe broad features of the design, not the full statistical analysis. The record does not report the randomization procedure, the masking procedures, the treatment sequence, or a statistical plan. It also reports no analysis results for the primary outcome.
What do the arm summaries describe?
The outcome is labeled as mean change from baseline. A mean is a measure of the center of a set of observations. The registry gives the same reported mean change, -1.3, for each treatment arm. It also gives the full range for each arm: -6.0 to 0.0 for gabapentin and -5.0 to 0.0 for placebo. A full range reports the lowest and highest observed values, but does not show how many observations fell between those endpoints or how concentrated the values were.
In general, means and ranges are descriptive statistics. They can summarize the observed data but do not, on their own, quantify uncertainty about a treatment contrast. The record does not report a standard deviation, standard error, or confidence interval for the outcome. A confidence interval is a statistical range that expresses uncertainty around an estimate under the assumptions of the analysis. Without a reported treatment-effect estimate and its uncertainty, the precision of the comparison cannot be assessed from these summaries.
Why does the crossover design matter?
In general, a crossover study compares treatments across periods, often using within-participant information. This can make the relationship between repeated observations important: measurements from the same person are usually not treated as if they came from unrelated people. A crossover analysis may also need to consider period and sequence effects, and whether an earlier treatment could influence a later-period measurement. The registry does not report how these issues were handled, whether a washout period was used, or whether a paired analysis was performed.
The posted arm counts are 6 for gabapentin and 6 for placebo, while enrollment is 9. Those figures should not be interpreted as independent parallel-group sample sizes or added to infer a total number of participants. The record does not state whether all participants contributed data under both treatments. It also does not explain the endpoint-specific analysis population or the handling of incomplete treatment periods.
What can be concluded without a treatment comparison?
The registry lists one outcome measure and zero analyses. It posts arm-level values but no direct estimate of the gabapentin-versus-placebo difference, no test statistic, and no p-value. A comparison cannot be reconstructed from the reported means and ranges alone because a crossover comparison depends on the relationship between each participant’s observations under the treatment conditions. That relationship is not reported.
In general, a nonsignificant result would not prove that treatments are equivalent, and similar descriptive means do not establish equivalence either. Equivalence or non-inferiority questions require an appropriate prespecified margin and analysis. Neither is reported in the registry record. In this case, the more basic limitation is that no inferential comparison is posted.
How should planning illustrations be read?
The registry’s planning note describes illustrations based on a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed trial results and not observed power. The note explicitly distinguishes them from the trial’s own design. No sample-size justification or power calculation for the original trial is reported in the registry record.
In general, planning calculations depend on assumptions about the effect to detect, variability, allocation, and analysis. They do not make an under-recruited or incomplete trial more informative after the fact. A planning estimate also does not replace an analysis of the trial’s actual outcome data. The registry record does not report the variance information or paired treatment contrast that would be needed to assess the precision of this crossover comparison.
Why might variability matter?
In general, variability describes how far observations tend to spread around a central value. Over-dispersion occurs when observed variability is greater than a model assumes; if it is ignored, uncertainty can be understated. The registry reports full ranges but not a variance estimate or a fitted model, so over-dispersion cannot be assessed from the posted summaries. More broadly, a range alone is not enough to establish whether a statistical model’s assumptions are appropriate.
The primary timeframe is listed as 19 weeks, while the outcome description names both the assessment after the first treatment and the assessment after the second treatment. No method for handling multiple time points or repeated outcome measurements is reported. The registry also does not say whether results were adjusted for baseline values or other variables. Without these details, the arm summaries should remain descriptive rather than being interpreted as a modeled treatment effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and no posted analyses. It does not report secondary outcomes. It also does not report whether there was a prespecified hierarchy of outcomes, a multiplicity adjustment, or a plan for selecting which assessment time to emphasize. The outcome description refers to assessments after the first and second treatment periods, while the primary timeframe is listed as 19 weeks. The record does not explain how those time points relate to the reported arm summaries.
Missing-data methods are not reported in the registry record. The trial enrolled 9, and the posted outcome summaries list 6 for each treatment arm. The record does not explain why the outcome counts differ from enrollment, whether the same participants contributed to both arm summaries, or whether incomplete observations occurred. It does not state how missing baseline or follow-up measurements were handled.
The analysis population is also not reported. The record does not specify whether the posted outcome includes all randomized participants, participants who completed treatment, or another subset. In a crossover study, incomplete periods can affect which within-participant comparisons are available. The record does not say whether a paired analysis was possible or how any incomplete treatment sequences were treated.
These omissions limit interpretation of the posted summaries. They do not establish that a particular analysis or adjustment was omitted from all trial conduct; they mean only that the registry record does not report it. No inference about the handling of missing data, multiplicity, or analysis populations can be made from the arm means and ranges alone.
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 |
|---|---|---|---|
| Gabapentin | 0 | 6 | 0.0% |
| Placebo Oral Capsule | 0 | 6 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Gabapentin | 0 of 6 |
| Placebo Oral Capsule | 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 |
|---|---|
| Gabapentin | 0 of 6 |
| Placebo Oral Capsule | 0 of 6 |
The registry reports safety figures separately for gabapentin and placebo oral capsule. For each listed treatment group, 6 were recorded as at risk for serious adverse events and 0 as affected. For other adverse events, each group also lists 6 at risk and 0 affected. Deaths are recorded as 0 in each group. No serious adverse-event terms are listed.
These are the counts recorded in the registry, not a complete description of every possible safety outcome. The record does not provide event-level detail, observation time by treatment, or an explanation of how adverse events were collected and classified. Because the study is crossover, the group counts should not be added or interpreted as numbers of distinct participants. They indicate the posted figures for each treatment group.
A recorded count of 0 means that the registry reports no affected participants for that category in the listed group; it does not show that an event is impossible or that the treatment has no risk. The small pilot study and early termination also restrict what can be inferred from these counts. The safety figures should be read as descriptive registry data, not as a precise comparison of safety between treatments.
12. What the Result Does, and Does Not, Mean
The registry documents a randomized, triple-masked crossover pilot study of gabapentin and placebo for vulvar pain. It records the primary endpoint as change from baseline in pain and posts the same mean change, -1.3, for each arm, together with a full range for each. These values describe the reported arm-level observations. They do not provide an estimate of the treatment difference.
The record does not report a statistical comparison, confidence interval, or p-value. It therefore does not establish whether the posted changes differed between gabapentin and placebo. Nor do matching arm means establish that the treatments are equivalent: equivalence requires a defined margin and an appropriate analysis, neither of which is reported. The ranges do not resolve this issue because they are descriptions of observed extremes, not uncertainty intervals for the treatment contrast.
The trial terminated early because of poor recruitment. Its enrollment was 9, and the outcome summaries list 6 in each arm, but the registry does not report the analysis population or explain the relationship between those counts. It also does not clarify which of the described assessment times is represented by the posted summaries. These gaps make the findings difficult to interpret beyond their descriptive content.
The posted data do not establish how gabapentin compares with placebo for vulvar pain, and the registry record does not report enough information to evaluate the precision or robustness of a comparison. The appropriate reading is limited: the registry contains arm-level outcome and safety summaries from a pilot study that ended early, but no reported inferential analysis. This is not a basis for a clinical recommendation.
13. Why This Trial Matters Statistically
This trial illustrates why study design and reported analysis need to be interpreted together. A crossover design can make within-participant comparisons informative, but the analysis must preserve that structure. Separate arm means and ranges do not reveal the paired differences between participants’ observations under gabapentin and placebo. Without those paired results or a reported model, the treatment comparison cannot be evaluated from the registry summaries.
The record also shows the distinction between descriptive results and inferential evidence. The same posted mean change appears for both arms, but that alone does not show equivalence, establish a lack of difference, or quantify uncertainty. A direct estimate with an appropriate measure of precision would be needed to assess the contrast. The registry reports no analysis for that comparison.
Early termination due to poor recruitment is relevant to the amount of information available. The recorded enrollment and outcome counts do not explain who contributed data to each treatment summary, whether complete crossover observations were available, or how missing observations were handled. These reporting details are important for readers assessing both the analysis population and the reliability of a crossover comparison.
Finally, the registry distinguishes planning illustrations from the trial’s own design. Planning calculations can show how assumptions relate to a future study’s information needs, but they are not observed power and cannot replace a completed analysis. For biostatisticians and clinical researchers, the record is a useful example of why outcome summaries, analysis methods, participant flow, and design-specific estimands all matter when interpreting a pilot trial.
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 trial ended early because of poor recruitment, and the registry gives no further account of recruitment progress or the decision to terminate. Enrollment was 9, while the outcome summaries list 6 for each treatment arm. The record does not explain the difference or report how many participants completed the crossover periods, so the completeness of the outcome data cannot be assessed.
The registry does not describe the treatment sequence, period structure, or any washout procedure. It also does not report whether potential period or carryover effects were considered. Those details are important in crossover studies because treatment-period structure can affect the interpretation of a within-participant comparison.
The primary outcome description names two assessment times, but the listed primary timeframe is 19 weeks and the record does not clarify which time point corresponds to the posted arm summaries. The subtraction convention for change from baseline is also not stated. This limits interpretation of both the timing and direction of the reported values.
No direct treatment-effect estimate, confidence interval, p-value, or analysis method is posted. The record does not identify the analysis population, describe missing-data handling, or report a sample-size justification for the original trial. Safety reporting is limited to group-level counts, without event-level descriptions or further collection details. These omissions mean the posted data can be described, but the precision and robustness of a treatment comparison cannot be assessed.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: To Evaluate if the Medication Gabapentin Lessens Vulvar Pain — NCT00390013.
- Registry record last updated 2017-07-31; status last verified 2017-07.
- Results first posted 2017-07-31.
- 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 record describes NCT00390013, a randomized, triple-masked crossover pilot study of gabapentin versus placebo oral capsule for vulvar pain. It lists enrollment of 9 and says the study terminated early due to poor recruitment.
The primary outcome was change from baseline in vulvar pain on an ordinal 0-10 scale. The posted arm summaries give a mean change of -1.3 for both gabapentin and placebo, with full ranges of -6.0 to 0.0 and -5.0 to 0.0, respectively. The registry reports no analysis comparing the treatments. It lists 0 serious adverse events, 0 other adverse events, and 0 deaths in each treatment group among the listed at-risk counts.
The record does not report an analysis population, missing-data approach, or the statistical method for the crossover comparison. The posted values should therefore be read as descriptive arm summaries rather than an inferential estimate of the treatment effect.