Light Treatment to Improve Symptom Management of Fibromyalgia Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Light Treatment to Improve Symptom Management of Fibromyalgia Syndrome (NCT03794908), a randomized na study. The primary outcome is Fibromyalgia Impact Questionnaire, Revised (FIQ-R) Score.

2. Clinical Question

The study’s stated purpose was to determine the effect of morning light treatment on physical function, pain intensity, and pain sensitivity in people with FMS. Its named primary outcome was the Fibromyalgia Impact Questionnaire, Revised (FIQ-R) score. The registry record also lists heat pain threshold, heat pain tolerance, and the PROMIS Pain Intensity Score as secondary outcomes.

The intervention descriptions specify the same daily duration and timing for both groups, while identifying the light conditions as bright and dim. The registry record does not give further details about light exposure, adherence, or how the two conditions were distinguished for participants or study staff. It also does not report a single primary contrast, such as a comparison of change between groups at a particular assessment. Instead, the primary outcome is described at baseline, mid-treatment, and post-treatment. The record’s note that the outcome has several time points and was not reduced to one comparison is important: without a selected contrast and its results, the registry information cannot answer how the groups differed on the primary outcome.

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study of light treatment for fibromyalgia syndrome. It records enrollment as 60 and identifies two device interventions: bright light and dim light, each delivered via the Re-Timer®. Both arm descriptions specify 60 minutes per day for the first hour after waking. The study is marked completed. Its recorded start date is 2019-01-31, and its primary completion date is 2021-07-15.

In a parallel-group design, participants are assigned to one of the study groups and remain in that group for the comparison. Random assignment is intended to make the groups comparable on average before treatment, although it does not guarantee that every characteristic is balanced in a particular trial. Masking can reduce the influence of expectations or knowledge of assignment on conduct or outcome assessment. The registry labels this trial double-masked, but does not identify which people were masked or describe how masking was maintained. These are general explanations of the design terms, not additional details about this trial.

The record does not report the randomization procedure, allocation ratio, concealment method, eligibility criteria, recruitment setting, participant characteristics, or actual numbers assigned to each group. It identifies a home light-treatment study in its official title and states that treatment was used after waking, but further details about device settings, adherence monitoring, or co-interventions are not reported in the registry record. The record also does not report the protocol or a statistical analysis plan.

Four outcome measures and two analyses are listed in the registry. The primary outcome is recorded at three assessment points: baseline, mid-treatment at 2 weeks post-baseline, and post-treatment at 4 weeks post-baseline. These assessment times describe the outcome schedule; they do not, on their own, identify which group contrast was designated as the primary statistical test. No numerical primary outcome results or analysis estimates are 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.

Before assignment: 60 participants were enrolled, and 57 participants were randomized.

Overall Study

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.

6. Primary Endpoint

The registry lists the primary outcome as Fibromyalgia Impact Questionnaire, Revised (FIQ-R) Score, measured over Baseline (1 week), Mid-Treatment (2 weeks post-baseline), Post-Treatment (4 weeks post-baseline).

The primary endpoint is the Fibromyalgia Impact Questionnaire, Revised (FIQ-R) score. The registry describes the FIQR as consisting of 21 questions, each with 11 boxes similar to a visual analog scale. Questions cover difficulty with physical activities and the severity of symptoms. The recorded scale runs from 0 - 100, with lower scores representing better functional status.

A patient-reported measure can capture a person’s assessment of symptoms and function that may not be represented by a single clinical observation. In general, a repeated score can describe how an outcome changes over time. To determine whether two groups differ, however, the assessment schedule needs to be paired with a defined comparison—for example, a contrast between groups at a specified time or a comparison of changes from baseline. The registry record lists three FIQ-R assessment points, but does not report which specific contrast was the primary one.

The registry identifies the FIQ-R as the primary outcome and records its unit as a score on a scale, with mean and standard deviation as the measure and dispersion. Those labels describe the intended summary format, not the actual results. The registry record does not report group means, standard deviations, changes, a between-group estimate, a confidence interval, or a p-value for the FIQ-R. Consequently, the direction and precision of the primary outcome findings cannot be assessed from the reported record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods turn outcome measurements into estimates that can be interpreted in light of uncertainty. In this trial, the registry describes a continuous primary outcome summarized by a mean and standard deviation. It does not report the analysis method used for the posted results, so the concepts below explain common statistical ideas rather than identify methods used in this study.

What does a mean describe?

General: A mean is the arithmetic average of the observed scores in a group. It gives a concise description of the group’s central value, but it does not show how much participants’ scores vary or how the distribution is shaped. A mean difference between groups can summarize a contrast, provided the groups and assessment time are clearly specified. For repeated measurements, the chosen contrast might concern scores at one follow-up time, change from baseline, or a pattern across multiple assessments. Those are not interchangeable questions.

The registry records the FIQ-R as measured at baseline, mid-treatment, and post-treatment and identifies mean and standard deviation as the summary and dispersion. It does not report the actual means or standard deviations. It also does not identify a single primary comparison across the listed assessment times. Without the estimate and its definition, it is not possible to tell what statistical question a numerical result would answer.

Why report a standard deviation?

General: A standard deviation describes the spread of individual observations around the mean. A small standard deviation indicates that observed values are relatively concentrated; a larger one indicates more variation. It is not the same as the standard error, which describes uncertainty in an estimated mean, and neither measure is itself an effect of treatment. Reporting both a group summary and a comparison estimate helps distinguish how scores are distributed from how groups differ.

For this trial, no FIQ-R standard deviations are reported in the registry record. The record therefore does not allow readers to assess the observed spread of scores or to reproduce an unadjusted comparison from summary statistics.

What does a confidence interval add?

General: A confidence interval expresses uncertainty around an estimate under a specified statistical procedure. A narrower interval indicates greater precision than a wider interval, all else being equal. The interval should be interpreted alongside the estimate and the outcome scale. It does not replace the estimate, and it does not by itself determine whether a difference is important to patients.

No confidence interval for the primary outcome is reported in the registry record. The precision of any primary effect therefore cannot be judged from the recorded results. There is also no reported threshold for an important FIQ-R difference, so a clinical-importance interpretation is not available from this record.

What does a p-value answer?

General: A p-value describes how unusual data at least as inconsistent with a specified null hypothesis would be under the assumptions of a statistical model. It is not the probability that the null hypothesis is true, and it does not measure the magnitude of an effect. A small p-value does not guarantee a meaningful effect; a larger p-value does not establish that two groups are equivalent.

The registry record does not report a p-value for the primary outcome. It also does not report whether tests were one-sided or two-sided in the trial’s own analysis, or identify the statistical model used. The two-sided significance level of 0.05 belongs to the stated planning illustration, not a reported test result.

How can repeated measurements be analyzed?

General: Repeated measurements on the same participant are related. A statistical approach that treats every observation as independent may fail to account for that relationship. Common approaches can estimate differences at selected times, average patterns over time, or changes relative to baseline while modeling within-participant correlation. The choice affects the interpretation of the estimate and can affect its uncertainty.

The FIQ-R schedule includes baseline, mid-treatment at 2 weeks post-baseline, and post-treatment at 4 weeks post-baseline. The registry record does not report whether the analysis used all assessments together, selected one follow-up, adjusted for baseline, or handled time as a categorical or continuous variable. It also does not report whether the analysis included an interaction between treatment group and time. No particular repeated-measures method should therefore be attributed to the trial based on the registry entry alone.

Why can over-dispersion matter?

General: Over-dispersion is a feature of some data in which variability exceeds what a chosen statistical model expects. It is most often discussed for counts or binary outcomes, rather than a continuous questionnaire score such as the FIQ-R. When present, ignoring over-dispersion can make standard errors too small and confidence intervals too narrow. The statistical approach should match the outcome and its distribution.

The registry records the primary endpoint as a continuous score summarized by a mean and standard deviation. It does not report distributional diagnostics or model assumptions, so there is no basis to state that over-dispersion was present or that a particular correction was used in this trial.

What do the planning illustrations mean?

General: A sample-size calculation asks how many participants would be needed to detect a specified effect under stated assumptions. Such a calculation depends on the effect size, variability, significance level, power target, allocation, and analysis method. Changing the effect to be detected changes the required sample size. A planning calculation is not a measure of how likely a completed trial was to find an effect after its results are known.

The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. The record details do not include the observed effect, the resulting participant counts, or a power target for any particular illustration. The record also does not report the trial’s own sample-size justification. These planning assumptions cannot be treated as evidence about the trial’s results or as observed power.

The registry identifies a continuous primary outcome, so its planning note that non-time-to-event results are expressed as participants per arm describes the kind of output such an illustration would use. No resulting count is reported in the record details. No additional calculation can be recovered from the assumptions alone without introducing values that are not reported.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is listed at three assessment points: baseline, mid-treatment, and post-treatment. The registry record notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not report which assessment or contrast was designated for the primary statistical test, nor how the multiple time points were accounted for in the analysis.

The registry also lists three secondary outcomes: heat pain threshold, heat pain tolerance, and PROMIS Pain Intensity Score. Considering multiple outcomes or multiple assessment times can increase the chance of at least one apparently notable result when many statistical tests are conducted. General approaches to address this include defining a hierarchy of outcomes, adjusting inference for multiple comparisons, or clearly distinguishing prespecified analyses from exploratory ones. The registry record does not report whether any such approach was planned or used. It also does not report a protocol or statistical analysis plan that would clarify the outcome hierarchy.

Information about missing observations is not reported in the registry record. The record does not state how many FIQ-R measurements were missing, why they were missing, or how missing data were handled. It also does not describe whether an analysis used all available observations, imputation, or another method. Missing-data assumptions can affect interpretation, especially when the likelihood of missingness is related to symptoms, treatment experience, or other observed or unobserved characteristics.

The analysis population is not reported in the registry record. In particular, the record does not specify whether the primary analysis included all randomized participants, participants who followed the assigned intervention, or another defined group. The number enrolled is recorded as 60, but that entry does not establish the number included in any outcome analysis. Interim analyses, stopping rules, and any adjustments associated with them are also not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry’s adverse-event figures record zero serious adverse events among 29 participants at risk in the bright-light group and zero among 28 participants at risk in the dim-light group. It also records zero other adverse events in each group and zero deaths in each group. These are the event counts and denominators listed in the record; they do not describe the primary FIQ-R outcome.

A zero count means that no events of that recorded category are listed among the participants included in the corresponding safety denominator. It does not establish that an event could never occur, or that the two groups have identical safety profiles. In general, event counts are interpreted in light of the number of participants observed, the duration of observation, how events were defined and collected, and the completeness of follow-up. Those details are not reported in the registry record.

The registry lists no top serious-event terms. The record does not report further information about the definition of serious events, event surveillance, exposure duration for safety analyses, or reasons that the adverse-event denominators differ from the enrollment entry of 60. The figures should therefore be read narrowly as the recorded counts and denominators, not as a complete characterization of safety or a comparison with other interventions.

12. What the Result Does, and Does Not, Mean

The record identifies a randomized comparison of bright and dim morning light in people with fibromyalgia syndrome and names the FIQ-R as the primary outcome. It also specifies the treatment duration and timing and lists several assessment points. Those details describe the question the trial was intended to address, but they do not provide the answer to the primary outcome question.

No numerical FIQ-R results are reported in the registry record: there are no group means, standard deviations, changes, between-group estimates, confidence intervals, or p-values. As a result, the direction, size, and precision of any difference cannot be determined from the available record. The same limitation applies to the listed secondary outcomes, for which numerical results are not reported in the record details.

The randomized design is relevant because random assignment can support a fair comparison by reducing systematic differences between groups at the start of a study. That design feature alone does not demonstrate that the groups were balanced in this trial, establish how participants were analyzed, or replace the need for outcome estimates and uncertainty measures. The registry’s double-masked designation also does not specify who was masked or how masking worked.

The recorded safety figures show zero serious events, zero other events, and zero deaths in both groups among the stated risk denominators. They are limited event counts and do not establish that the interventions have identical safety or that no unrecorded events occurred. The record does not provide the details needed for a broader safety assessment.

The planning illustration is described in terms of an observed effect and stated statistical assumptions, but its effect value and resulting participant counts are not reported in the record details. Such planning quantities, even if available, would not substitute for the observed outcome estimates. The registry information therefore supports describing the trial’s design and recorded outcomes, but not drawing a conclusion about whether bright or dim light produced a different FIQ-R result.

13. Why This Trial Matters Statistically

This trial raises a useful statistical question about how to compare a patient-reported outcome measured repeatedly during a randomized study. The FIQ-R is scheduled at baseline, mid-treatment, and post-treatment. A clear interpretation requires knowing which comparison is primary: a difference at a particular follow-up, a difference in change from baseline, or a treatment-group pattern across assessment times. These approaches can address different questions, so naming the outcome and schedule alone is not enough to define the estimand.

The registry record also illustrates why effect estimates and uncertainty matter alongside design descriptions. Randomization and masking describe features that can strengthen a comparison, but they do not convey the size or precision of an outcome difference. Without group summaries, a between-group estimate, or a confidence interval, readers cannot judge whether the results are compatible with a range of effects or how precisely the comparison was estimated.

Multiplicity is relevant because the record lists more than one outcome and several primary-outcome time points. A prespecified hierarchy or a clearly described multiplicity approach can help readers understand how findings across multiple tests should be interpreted. The registry record does not report such a plan. Missing-data methods and analysis populations are also important for repeated measurements, but are not reported.

Finally, a planning illustration based on an observed effect should be kept distinct from the trial’s original design justification and from the outcome results. The record states assumptions for a planning illustration but does not report its input effect or output counts. Keeping these categories separate prevents a planning exercise from being mistaken for evidence about what happened in the 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 main limitation for interpreting this trial from the registry record is the absence of numerical primary outcome results. The FIQ-R is described and its assessment schedule is recorded, but group means, standard deviations, changes, between-group estimates, confidence intervals, and p-values are not reported. This prevents assessment of effect direction, magnitude, and precision.

The primary outcome spans baseline, mid-treatment, and post-treatment, and the record notes that it was not reduced to one comparison. The specific primary contrast and the statistical method used are not reported. Without that information, even a numerical result would require context to understand which question it answers. The record also does not report the protocol, a statistical analysis plan, multiplicity procedures, or analysis populations.

Participant flow and baseline characteristics are not reported in the registry record. Although enrollment is recorded as 60, the numbers assigned to each group and the numbers included in the primary analysis are not reported. The record does not describe eligibility criteria, participant characteristics, missing outcome data, reasons for missingness, or methods for handling missing measurements. It also does not describe adherence or treatment exposure beyond the stated daily duration and timing.

The registry labels the study double-masked but does not report who was masked or how masking was maintained. It does not describe the randomization procedure, allocation concealment, or the details of the two light conditions beyond their bright and dim labels and shared device. These omissions limit assessment of implementation and possible sources of bias.

Safety reporting is limited to the recorded adverse-event counts and denominators. Definitions, surveillance procedures, follow-up duration for safety, and the reason for the denominators are not reported. The planning illustration’s observed effect and resulting participant counts are also not reported, and the trial’s own sample-size justification is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Light Treatment to Improve Symptom Management of Fibromyalgia Syndrome — NCT03794908.
• Registry record last updated 2022-10-05; status last verified 2022-09.
• Results first posted 2022-10-05.
• 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.

18. Record Summary

The registry describes a completed randomized, double-masked, parallel-group study of bright versus dim light delivered via the Re-Timer® for people with fibromyalgia syndrome. Both interventions are described as 60 minutes per day during the first hour after waking. Enrollment is recorded as 60; the recorded start date is 2019-01-31 and the primary completion date is 2021-07-15.

The primary outcome is the FIQ-R score, assessed at baseline, mid-treatment at 2 weeks post-baseline, and post-treatment at 4 weeks post-baseline. The registry also lists heat pain threshold, heat pain tolerance, and PROMIS Pain Intensity Score as secondary outcomes. Numerical outcome results and the primary statistical comparison are not reported in the registry record.

The adverse-event figures record zero serious events, zero other events, and zero deaths in each group, with 29 participants at risk in the bright-light group and 28 in the dim-light group. Further details about safety methods, missing data, analysis populations, and the statistical analysis plan are not reported in the registry record.