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 Benefits of Tanning in Fibromyalgia Patients (NCT00447083), a randomized na study. The primary outcome is Pain Relief Success Rates (Phase I).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00447083 |
| Phase | NA |
| Condition | Fibromyalgia Syndrome |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Double |
| Enrollment | 19 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Wake Forest University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with Fibromyalgia Syndrome. The registry record lists enrollment of 19. The posted outcomes refer to a Phase I period, and the record describes participants who completed an acclimation phase before being randomized to the exposure regimens. Further eligibility criteria, participant characteristics, and details about how many people completed each phase are not reported in the registry record.
Intervention
The intervention was UVB exposure in tanning beds. The arm description says that the regimen after acclimation involved treatments 3 times/week for 6 weeks, with a fixed dose of 10 min. The record also describes an acclimation period involving 6 sessions, with exposure time progressively increased from 3 minutes to 9 minutes. Those acclimation details are presented for UVB and non-UVB exposure.
Comparator
The comparator was non-UVB exposure in tanning beds. Its described regimen after acclimation also involved treatments 3 times/week for 6 weeks, with a fixed dose of 10 min. The non-UVB acclimation exposures were described as mirroring the UVB schedule. The registry calls the study double-masked and crossover, but it does not report enough detail to establish how masking was maintained or how treatment order and transitions were handled.
Primary question
The primary question was whether exposures were followed by pain relief, defined as a 2 point improvement on an 11 point Likert scale. The outcome was the percentage of exposures with relief over 2 weeks in Phase I. The record also states broader aims: to assess acute pain perceptions after ultraviolet exposure and whether a series of exposures has a cumulative effect. The posted primary results give percentages for each exposure condition, but a two-arm inferential comparison is not estimable from the posted outcome.
3. Trial Design
This was a randomized, double-masked, crossover pilot study listed as completed. The registry identifies Wake Forest University as sponsor and gives the study title as “Benefits of Tanning in Fibromyalgia Patients.” The official title describes a pilot study of ultraviolet light and pain in persons with fibromyalgia syndrome. The record lists phase as NA. The study start is recorded as 2005-05 and primary completion as 2008-09.
The record describes an acclimation period followed by randomization to UVB or non-UVB exposure. During acclimation, each described group had 6 tanning sessions over 2 weeks, with exposure time increasing from 3 minutes to 9 minutes. The descriptions say the non-UVB schedule was intended to mirror the UVB schedule. After acclimation, the arm descriptions give a regimen of treatments 3 times/week for 6 weeks, using a fixed dose of 10 min for UVB and non-UVB exposure.
The crossover label means that the study was organized around participants receiving more than one condition, rather than being a simple parallel-group comparison. In a crossover design, within-person comparisons can reduce the influence of stable differences between participants. However, the registry record does not report the treatment sequence details, the length or use of any washout period, or how data from the different periods were incorporated into the analysis. Those details matter because order, carryover, and period effects can influence crossover results.
Enrollment is listed as 19, and the posted outcome records show 19 for each exposure condition. These figures should be understood within the crossover structure, not as evidence of separate parallel groups. The record does not report the number of participants completing each phase or the analysis population. Randomization and masking are identified, but their procedures are not reported in 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.
Phase I
| Stage | Phase I - UVB First | Phase I - Non-UVB First | Phase II - UVB Exposure | Phase II -Non-UVB |
|---|---|---|---|---|
| STARTED | 10 | 9 | 0 | 0 |
| COMPLETED | 10 | 9 | 0 | 0 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
Phase II
| Stage | Phase I - UVB First | Phase I - Non-UVB First | Phase II - UVB Exposure | Phase II -Non-UVB |
|---|---|---|---|---|
| STARTED | 0 | 0 | 8 | 8 |
| COMPLETED | 0 | 0 | 7 | 7 |
| NOT COMPLETED | 0 | 0 | 1 | 1 |
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 | UVB First | Non-UVB First | Total |
|---|---|---|---|---|
| Participants analysed | 10 | 9 | 19 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 10 | 9 | 19 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 10 | 9 | 19 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 10 | 9 | 19 |
6. Primary Endpoint
The registry lists the primary outcome as Pain Relief Success Rates (Phase I), measured over 2 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of exposures with relief |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled “Pain Relief Success Rates (Phase I).” It measures the percentage of exposures followed by pain relief during a 2 weeks timeframe. Relief was defined as a 2 point improvement on an 11 point Likert scale. Unlike an endpoint that summarizes a participant’s average score, this endpoint classifies individual exposures according to whether the specified improvement occurred, then expresses relief as a percentage of exposures.
This type of endpoint is intended to capture the frequency of short-term relief events, rather than only the average level of pain after a treatment period. That can be useful when the research question concerns whether relief occurs after exposure. It also creates an analysis challenge: multiple exposures from the same participant are not necessarily independent observations. Exposures from one person may be more alike than exposures from different people. A suitable analysis may need to account for that clustering, but the statistical method for the primary endpoint is not reported in the registry record.
The posted values are 33.0 for UVB Exposure and 16.0 for Non-UVB Exposure, in the stated percentage-of-exposures measure. The registry record does not provide an estimable two-arm comparison for this count-other endpoint. The displayed percentages therefore describe each exposure condition, but they do not by themselves establish the precision or statistical uncertainty of the contrast between conditions. The record does not report confidence intervals or a p-value for the primary result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary outcome describes the percentage of exposures meeting the specified pain-relief threshold during Phase I. The posted value is 33.0 for UVB Exposure and 16.0 for Non-UVB Exposure. These are descriptive results. The registry record indicates that values are missing or not estimable for a two-arm comparison of this count-other endpoint, so it does not provide an inferential estimate of the difference, a confidence interval, or a p-value for the primary comparison.
That distinction is important. Seeing two percentages does not show how precisely the underlying difference has been estimated. In particular, the outcome is based on exposures within participants, and observations from the same participant may be related. Without a reported analysis that accounts for the crossover structure and repeated exposures, the percentages alone cannot establish the amount of uncertainty around a comparison or whether the observed pattern is compatible with chance variation.
A secondary endpoint gives mean post-treatment Likert scores over 2 weeks: 4.89 for UVB Exposure and 5.21 for Non-UVB Exposure. The reported mean difference, comparing Non-UVB Exposure with UVB Exposure, is 0.32, with a 95% confidence interval from -1.334 to 1.974 and an unadjusted p-value of 0.704. The interval includes zero and spans values on either side of zero. In general, a confidence interval describes a range of estimates compatible with the data under the analysis assumptions; its width conveys precision. The reported interval is broad relative to the point estimate, so the secondary comparison is imprecise. The unadjusted p-value does not indicate strong evidence against a zero mean difference under the stated analysis, but it is not a probability that either treatment is effective or ineffective.
The secondary comparison is presented as an unadjusted re-calculation from posted summary statistics. The registry record does not report an analysis for it. The trial is identified as a crossover, while the posted comparison is based on the summary statistics for the two exposure conditions. It should not be assumed that this calculation accounts for within-participant pairing, period effects, or carryover. The sponsor's own analysis takes precedence if it is available, but no reported analyses are listed in the record.
None of these results supports a definitive conclusion about the broader study aims. The primary endpoint lacks an estimable contrast, and the secondary comparison has substantial uncertainty and is unadjusted. The record also does not report the underlying participant-level data, an analysis plan, or enough design detail to assess whether the posted summary comparison reflects the crossover structure. The appropriate reading is therefore descriptive and cautious: the record contains outcome values, but the inferential evidence for a treatment contrast is limited.
9. Statistical Methods Explained
The study is described as randomized, double-masked, and crossover. These design labels address different features. Randomization is intended to reduce systematic differences in treatment assignment. Masking is intended to limit the influence of knowledge about exposure assignment on participants or study personnel. A crossover design exposes participants to more than one condition, permitting comparisons within the same person. The registry record names these features but does not describe the randomization procedure, who was masked, or how the crossover sequence was implemented.
In a crossover study, measurements from the same participant are usually related. For example, a participant's pain ratings under one condition may resemble that participant's ratings under another condition because of stable personal characteristics. A method that treats observations as independent can misstate uncertainty when that relationship is ignored. Period effects can also matter if pain changes over time regardless of exposure, and carryover can matter if an earlier condition influences outcomes in a later period. The record does not report whether or how the primary analysis addressed within-participant correlation, period effects, or carryover.
What does the primary endpoint count?
The primary endpoint is the percentage of exposures with pain relief, with relief defined as a 2 point improvement on an 11 point Likert scale. This is a repeated binary-type outcome at the exposure level: an exposure either meets the stated improvement criterion or does not. Summarizing such observations as a percentage is straightforward descriptively, but comparing conditions requires attention to the number of exposures and how those exposures are grouped within participants. The record does not report the total exposure counts used in each percentage, the distribution of exposures across participants, or the primary statistical model.
Because the primary endpoint is classified as count other, the posted results do not support the standard two-arm comparison calculation used for the continuous secondary endpoint. The registry record explicitly indicates that values are missing or not estimable for a two-arm comparison. This is not a reason to infer a particular model or a particular unreported result. It means the record supplies descriptive percentages but no reported contrast with an uncertainty estimate.
How should the secondary score comparison be read?
The secondary continuous endpoint is a post-treatment pain score on a scale. Its posted summaries are means and standard deviations for UVB Exposure and Non-UVB Exposure. The recalculated comparison is an unadjusted mean difference, with a 95% confidence interval and an unadjusted p-value. A mean difference expresses the contrast in average scores in the scale's units. The confidence interval describes uncertainty around that contrast under the calculation's assumptions. An interval spanning zero includes no mean difference among the values compatible with the calculation; it also includes differences in either direction.
This re-calculation uses posted summary statistics and is not a substitute for a trial-specific analysis. For a crossover design, an analysis based on paired participant data can use the within-person relationship, while a comparison of group summaries may not. The record does not report the sponsor's analysis for this secondary endpoint, and the listed reported analyses are empty. The recalculated p-value is unadjusted, meaning it does not account for the possibility of examining multiple outcomes or comparisons.
What do the planning figures mean?
The planning illustration is based on the observed effect and assumes a two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. It gives participants per arm for 80% power and participants per arm for 90% power under scenarios that plan for 100% of the observed effect, 75% of the observed effect, or 50% of the observed effect. These are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. They are also framed as a two-arm planning calculation, so they do not establish the sample size needed for a crossover design or for the primary repeated-exposure endpoint.
Power is a design concept describing the chance that a planned analysis will detect an effect of a specified size under its assumptions. It is not a measure of how convincing an already observed result is. In general, planning for a smaller effect requires more information to detect it reliably. The listed figures should therefore be read as conditional scenarios, not as recommendations or as proof that a given study size would be adequate. The actual sample-size justification and statistical plan are not reported in the registry record.
Why can repeated outcomes require special methods?
In general, over-dispersion occurs when outcome variability is greater than a simple model expects. For count or binary outcomes, clustering can contribute to this: events within one participant may be more alike than events across participants. If this dependence is ignored, standard errors can be too small or otherwise inaccurate, making confidence intervals and tests unreliable. Methods that model participant-level clustering or use participant-level summaries can address this issue, but the registry record does not say which, if any, was used for the primary endpoint.
Likewise, missing outcomes can affect an estimate if the likelihood of missingness is related to participants' pain, exposure, or response. The record does not describe missing-data handling, exclusions, or the analysis population. These are not minor reporting details: they determine which observations contribute and what assumptions support the resulting inference.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies a primary endpoint and lists secondary outcomes, but the statistical plan is not reported in the registry record. It does not state whether secondary analyses were prespecified, whether any outcome hierarchy was used, or whether adjustments for multiple comparisons were planned. When more than one outcome or comparison is examined, unadjusted tests can make chance findings more likely across the set. This does not invalidate a particular result, but it limits the weight that should be placed on an isolated unadjusted result.
Missing-data procedures are also not reported. The record does not describe how missing pain ratings or incomplete exposure sequences were handled, whether participants were excluded from particular analyses, or whether any sensitivity analyses were performed. Those details affect which observations contribute to each estimate and whether missingness could bias the result.
The analysis population is not reported in the registry record. Although enrollment is listed as 19 and the posted outcome groups each show 19, the record does not specify whether the outcome summaries include all enrolled participants, only completers, or another analysis set. This matters particularly in a crossover study, where participants may contribute data under more than one condition and may not complete every period.
The record lists one analysis and two posted secondary outcomes, but reported analyses are absent. It does not report an interim analysis plan, a stopping rule, or the sample-size justification. The study's randomization and masking labels do not fill these gaps: design labels do not establish how missingness, multiplicity, or analysis populations were handled. Without these details, readers cannot determine whether the posted comparisons reflect a prespecified analysis or how robust they are to alternative reasonable analytic choices.
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 |
|---|---|---|---|
| UVB Exposure | 0 | 19 | 0.0% |
| Non-UVB | 0 | 19 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| UVB Exposure | 0 of 19 |
| Non-UVB | 0 of 19 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| UVB Exposure | 0 of 19 |
| Non-UVB | 0 of 19 |
The adverse-event figures report zero serious adverse events among 19 at risk in each exposure condition, and zero deaths in each condition. Other adverse events are also reported as zero among 19 at risk in each condition. These are the posted registry counts; they should be read as descriptions of events recorded during the study, not as proof that an exposure carries no risk.
Safety counts in a small pilot study have limited ability to characterize uncommon events. A zero count means that no event of that category was recorded in the listed group during the period represented by the registry entry. It does not establish that the underlying risk is zero, and it does not tell readers how outcomes were monitored or classified. The record does not report the event-collection procedures, follow-up duration for safety, or detailed adverse-event definitions.
The crossover structure also means the exposure-condition records should not be interpreted as independent parallel groups. The registry's risk counts and event counts are presented by condition, but the safety analysis details are not reported. No serious adverse-event terms are listed. These figures are therefore a concise account of the posted safety record, with substantial limits on broader safety inference.
12. What the Result Does, and Does Not, Mean
The posted results describe pain-related outcomes after UVB and non-UVB exposure in a randomized, double-masked crossover pilot study. The primary endpoint is the percentage of exposures meeting a defined improvement threshold. The record reports 33.0 for UVB Exposure and 16.0 for Non-UVB Exposure, but does not provide an estimable two-arm comparison for this endpoint. The figures alone do not show the uncertainty around a contrast or establish that the conditions differ.
The secondary post-treatment pain-score comparison reports a mean difference of 0.32, with a 95% confidence interval from -1.334 to 1.974 and an unadjusted p-value of 0.704. This is an imprecise, unadjusted summary-statistic comparison, and the interval spans zero. It should not be interpreted as proof of equivalence, proof of no effect, or proof of benefit. A wide interval can be compatible with a range of possible differences, while the p-value is tied to the assumptions of the calculation and is not a probability that a hypothesis is true.
The record does not provide the primary endpoint's inferential comparison or report the sponsor's analyses. It also does not describe enough of the crossover analysis to determine whether the posted secondary calculation accounts for paired responses, period effects, or carryover. The findings therefore do not answer the broader question of whether a series of exposures has a cumulative effect, and they do not establish a durable effect beyond the reported outcome timeframe.
These results are not a basis for medical advice. They are a limited statistical record from a pilot study. The primary percentages are descriptive, the secondary comparison has substantial uncertainty, and the analysis plan and population are not reported. Conclusions should be kept within those boundaries rather than extended to clinical effectiveness, long-term outcomes, or people not represented in the study.
13. Why This Trial Matters Statistically
This trial is statistically instructive because its design and primary outcome create different analytic demands. The study is labeled crossover, which can support within-person comparisons, while its primary endpoint summarizes relief across repeated exposures. Both features require careful accounting for dependence among observations. Treating each exposure as independent could misrepresent uncertainty if exposures from the same participant are correlated.
The record also illustrates the difference between descriptive results and an inferential comparison. Percentages are posted for the primary endpoint, but an estimable two-arm comparison is not. In contrast, the secondary score has a recalculated mean difference and confidence interval, yet that calculation is unadjusted and is not documented as the sponsor's analysis. The two kinds of information are not interchangeable: descriptive percentages can show the observed pattern, while an inferential comparison needs an estimate of uncertainty based on an appropriate analysis.
Small pilot studies can be useful for exploring feasibility and generating hypotheses, but their estimates may be imprecise. The posted planning figures are illustrations based on the observed effect under stated assumptions, not observed power and not the trial's own design justification. This distinction helps prevent a planning calculation from being mistaken for evidence about the reliability of the current results.
Finally, registry reporting determines how much readers can learn from results. Here, important details about the primary analysis, crossover handling, missing data, multiplicity, and analysis populations are not reported in the registry record. That absence does not prove that no such work occurred; it limits what can be evaluated from the registry entry. The study is therefore a useful example of why outcome definitions, analysis methods, and uncertainty estimates need to be reported together.
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 limitations are specific to interpreting this record. The primary endpoint is a repeated exposure-level percentage, but the exposure counts underlying the percentages and the distribution of observations across participants are not reported. Without these details, the precision of the primary percentages and the dependence structure cannot be evaluated. The registry also does not provide an estimable two-arm comparison for this endpoint.
The crossover design raises questions that the record does not answer. Treatment sequence details, washout procedures, period effects, carryover, and the handling of within-participant correlation are not reported in the registry record. The arm descriptions give exposure schedules, but they do not explain how the crossover periods were analyzed or whether all participants contributed data to both conditions.
The record does not report participant characteristics, eligibility details, completion by phase, or the analysis population. It also does not explain missing-data handling, the statistical plan, multiplicity procedures, or the rationale for sample size. The list of reported analyses is empty, limiting comparison between posted summaries and any trial-specific analysis.
The secondary result is a simple unadjusted re-calculation from posted summary statistics. It may not reflect a paired crossover analysis, and it does not account for multiple outcomes. The associated planning illustration is conditional on its stated assumptions and should not be read as a design recommendation for this trial. Finally, the safety counts are descriptive and do not establish the absence of risk. Together, these limitations restrict the conclusions that can be drawn from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Benefits of Tanning in Fibromyalgia Patients — NCT00447083.
- Registry record last updated 2018-11-13; status last verified 2018-10.
- Results first posted 2018-11-13.
- 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 a completed randomized, double-masked crossover pilot study sponsored by Wake Forest University. It lists Fibromyalgia Syndrome as the condition, enrollment of 19, and a study start of 2005-05 with primary completion in 2008-09. The described exposures were UVB and non-UVB tanning-bed sessions, with an acclimation period followed by the stated six-week treatment regimen.
The primary endpoint was the percentage of exposures with pain relief over 2 weeks in Phase I, defined as a 2 point improvement on an 11 point Likert scale. Posted values were 33.0 for UVB Exposure and 16.0 for Non-UVB Exposure, but a two-arm comparison was not estimable. A secondary post-treatment pain-score comparison was recalculated from posted summary statistics and is unadjusted. The record does not report sponsor analyses or key details about crossover analysis, missing data, multiplicity, and analysis populations. Safety entries report zero serious adverse events, other adverse events, and deaths in the listed exposure groups.