Gulf War Illness Inflammation Reduction Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Gulf War Illness Inflammation Reduction Trial (NCT02506192), a randomized phase 2 study. The primary outcome is Change From Baseline of Veterans RAND 36-Item Health Survey Physical Component Summary Score (PCS) Scores at 8 and 16 Weeks.

2. Clinical Question

3. Trial Design

The Gulf War Illness Inflammation Reduction Trial was a randomized, parallel-group Phase 2 trial with triple masking. The registry record lists an enrollment of 83 and identifies modified-release prednisone and placebo as the two interventions. It does not state which participant, clinician, or outcome-assessment roles were included in the triple masking, so the exact masking arrangement is not reported in the registry record.

The stated objective was to determine whether anti-inflammatory treatment with prednisone improves health-related quality of life in veterans with Gulf War Illness. The primary outcome focused on the physical component score, while the listed secondary outcomes covered pain, fatigue, cognitive failures, mental health-related quality of life, and peripheral blood biomarkers associated with Gulf War Illness. The primary outcome timeframe includes baseline and assessments at 8 and 16 weeks.

The registry record gives the start as 2015-07 and the primary completion date as 2023-10-19. The trial status is completed. These dates describe the recorded trial timeline; they do not indicate when results were analyzed or reported. The record does not give further details about recruitment, participant flow, adherence, treatment discontinuation, or follow-up completeness.

Although the design is randomized, the numerical results needed to compare the groups are not reported in the registry record. In particular, there are no posted group means, changes from baseline, between-group estimates, confidence intervals, or p-values for the primary outcome. The record therefore identifies the comparison and its planned time points, but does not support a quantitative estimate of the observed difference.

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.

Overall Study

Reasons for not completing this period:

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 Change From Baseline of Veterans RAND 36-Item Health Survey Physical Component Summary Score (PCS) Scores at 8 and 16 Weeks, measured over 0, 8, and 16 weeks.

The primary endpoint is change from baseline in the Veterans RAND 36-Item Health Survey Physical Component Summary score at 8 and 16 weeks. The instrument is described as a modification of the SF-36 and covers health concepts including physical functioning, limitations due to physical problems, bodily pain, general health perceptions, energy and vitality, social functioning, limitations due to emotional problems, and mental health. Its physical and mental component summary scores combine information from these concepts.

The physical component score is intended to represent health-related quality of life related to physical functioning and symptoms. The score is standardized and ranges from 0 to 100; the reference US population mean is 50 points with a standard deviation of 10 points. Higher scores indicate better health status. These scale properties help explain what a score represents, but they do not supply the trial’s observed results.

Change from baseline focuses attention on how scores differ from participants’ starting values over follow-up. Comparing those changes between randomized groups can estimate the treatment-group contrast, subject to the analysis method and assumptions. The registry record does not report the group-level scores or the statistical estimate for either follow-up time, so the magnitude, direction, and precision of the primary endpoint contrast cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For a continuous outcome such as a health-related quality-of-life score, a mean describes the average score in a group, while a standard deviation describes how dispersed individual scores are around that average. The primary endpoint is a change from baseline, so an analysis could describe average changes within each randomized group and compare those changes between groups. These are general statistical concepts; the registry record specifies a mean and standard deviation as the outcome parameter and dispersion, but does not report the actual group summaries or the analysis used.

What does a between-group estimate represent?

A between-group estimate expresses the difference in outcome between the randomized treatment strategies, under a defined analysis. For a change-from-baseline endpoint, the estimate could compare the groups’ average changes. A within-group change alone does not answer the randomized comparison: participants may change over time for reasons unrelated to assigned treatment. The between-group contrast is the quantity needed to describe the comparative result. No such estimate is reported for the primary endpoint in the registry record.

Randomization is intended to create groups that are comparable on average at the point of assignment. It supports a fair comparison when the analysis and follow-up preserve the randomized groups and when missing observations and other departures are handled appropriately. Randomization does not by itself guarantee that every participant has an observed outcome at each follow-up, nor does it resolve how missing data should be treated. The registry record does not report the analysis population, participant flow, or missing-data method.

How should uncertainty be read?

A confidence interval is a range of estimates compatible with the observed data and the assumptions of the statistical method. Its width conveys precision: a narrower interval generally indicates a more precise estimate, while a wider interval indicates greater uncertainty. A confidence interval also shows which effect sizes remain plausible under the analysis. It is not reported for the primary outcome in the registry record, so the precision of any treatment-group difference cannot be evaluated.

A p-value, when reported, measures how surprising data at least as inconsistent with a specified null hypothesis would be under that hypothesis and the model assumptions. It does not measure the probability that the null hypothesis is true, the size of an effect, or its clinical importance. The primary p-value is not reported in the registry record. In the absence of an estimate and uncertainty interval, a p-value alone would also be insufficient to characterize the result.

Why do multiple outcomes and time points matter?

The primary outcome includes follow-up at 8 and 16 weeks, and the registry lists secondary outcomes for pain, fatigue, cognitive failures, mental component summary score, and peripheral blood biomarkers. When several outcomes or time points are tested, the chance of obtaining at least one apparently notable result can increase if each is interpreted independently. Statistical methods can address this multiplicity, for example by adjusting significance criteria or by defining a hierarchy of outcomes in advance. These are general options, not claims about this trial. The registry record does not report a multiplicity strategy or analysis plan.

Repeated measurements from the same participant are generally related rather than independent. A statistical model for repeated measures can account for that correlation and may use information across follow-up times. Alternatively, separate analyses at each time point have different interpretive and multiplicity implications. The record does not identify which approach was used, so neither should be attributed to the trial.

What does over-dispersion mean for these outcomes?

Over-dispersion is a general issue for outcomes whose observed variability exceeds what a chosen statistical model expects. It is especially relevant to count or event data and to models that assume a particular relationship between a mean and variance. The primary endpoint is a continuous score summarized by a mean and standard deviation, and the registry record does not report an over-dispersion assessment or a model. No conclusion about the presence or handling of over-dispersion can be drawn from the registry record.

The record 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 says that the effect to detect is a stated fraction of the observed effect and that non-time-to-event illustrations are expressed as participants per arm for 80% power. These are planning assumptions, not a result from the trial and not observed power. Numerical illustration results and the underlying observed effect are not reported in the registry record. The trial’s own sample-size justification is also not reported, so the planning illustration should not be treated as the original design rationale.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome has measurements at 8 and 16 weeks, and several secondary outcome domains are listed. Testing multiple outcomes or time points can complicate interpretation because the overall chance of false-positive findings can grow when many comparisons are considered. As a general matter, a prespecified testing hierarchy or an adjustment for multiplicity can help control that risk. The registry record does not report whether either approach was planned or used, and it does not provide outcome-specific test results.

Missing-data handling is also important for change-from-baseline outcomes. If participants do not provide a follow-up score, the analysis must make choices about which observations to include and how to address the unobserved values. Different assumptions can lead to different estimates, particularly if missingness is related to health status or treatment experience. The registry record does not report the amount or pattern of missing primary-outcome data, the method used to handle missingness, or sensitivity analyses.

The analysis population is not reported in the registry record. It is therefore not possible to determine whether the primary comparison included all randomized participants, only those with observed follow-up, or another defined group. The record also does not report a detailed statistical analysis plan, the model used, covariate adjustment, or treatment of protocol deviations. These omissions limit assessment of how the planned comparison was translated into an analysis and how robust any result would be to alternative assumptions.

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 0% reporting threshold.

The registry record lists 42 participants at risk in the treatment group and 41 in the placebo group. It records zero serious adverse events in each group, zero other adverse events in each group, and zero deaths in each group. These are the posted counts and their accompanying at-risk group sizes.

Zero recorded events does not establish that a treatment has no safety risks. It describes only the events captured and reported under the registry record’s categories and observation period. The record does not provide event definitions, detailed collection procedures, the duration of safety follow-up, or information about events that may have occurred but were not included in these counts. It also does not list serious adverse-event terms.

The adverse-event denominators should not be assumed to be the primary-outcome analysis counts. The registry record does not state how many participants contributed PCS measurements at baseline, 8 weeks, or 16 weeks. These safety figures can be read as reported counts, but they do not establish comparative safety beyond those counts or explain the balance of benefits and risks.

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

The trial’s stated aim was to assess whether modified-release prednisone changes health-related quality of life related to physical functioning and symptoms in veterans with Gulf War Illness, compared with placebo. Its primary measure, follow-up times, and randomized comparison are identified in the registry record. The record also identifies secondary measures addressing pain, fatigue, cognitive failures, mental health-related quality of life, and peripheral blood biomarkers.

What the posted results do not provide is the numerical primary outcome result. Without group-specific changes and a between-group estimate, it is not possible to describe the observed direction or magnitude of the contrast. Without a confidence interval, the precision and range of plausible effects cannot be assessed. Without a reported analysis method and analysis population, the assumptions underlying any estimate cannot be evaluated. The completed status and study objective do not fill these gaps.

Even when a numerical difference is available, statistical evidence and clinical importance are distinct questions. Statistical uncertainty concerns how precisely an effect is estimated under a model; clinical interpretation asks whether the size of the effect would matter in the context of the outcome and population. The registry record does not report an effect estimate or a threshold for interpreting a meaningful change, so neither question can be answered for this trial from the posted results.

The safety counts record no serious adverse events, other adverse events, or deaths in either group. These counts do not establish that no events occurred outside the recorded categories or follow-up, and they cannot by themselves establish that either treatment is safe or unsafe. The available information supports a description of the design and reported counts, not a treatment recommendation or a conclusion about efficacy.

13. Why This Trial Matters Statistically

This trial illustrates why a registry description and a statistical result answer different questions. The record specifies a randomized, triple-masked comparison, identifies the health-related quality-of-life construct, and names follow-up times. Those details let readers understand what investigators intended to measure. But interpretation of a treatment comparison depends on the observed estimates and their uncertainty, and those numerical primary-outcome results are not reported in the registry record.

It also highlights the importance of defining an endpoint clearly. The physical component summary score brings together several aspects of health, while its direction and scale help explain what a score means. A clearly described measure does not, on its own, reveal whether groups changed differently. Readers need the between-group estimate, its precision, and enough analysis information to understand the comparison.

The multiple follow-up times and secondary outcomes make prespecification and multiplicity relevant statistical concerns. Reporting how comparisons were prioritized or adjusted can help readers distinguish a primary test from exploratory findings. Likewise, transparent reporting of participant flow, analysis populations, and missing-data methods helps show which observations support the estimates and how sensitive conclusions may be to incomplete follow-up.

Finally, the adverse-event figures demonstrate the distinction between a count and a broad safety conclusion. Counts are interpretable only alongside their denominators, event definitions, and observation context. The registry record provides group sizes and zero counts, but not the additional detail needed for a comprehensive safety assessment. These are general lessons in interpreting clinical-trial evidence, not claims that a particular unreported analysis was or was not performed.

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 principal limitation for statistical interpretation is that the registry record does not report numerical primary-outcome results. Group means, changes from baseline, between-group estimates, confidence intervals, and p-values are absent. The record therefore does not permit assessment of the primary result’s direction, magnitude, or precision.

The registry record also does not describe the analysis method or analysis population. It does not report participant flow by follow-up time, the amount or pattern of missing outcome data, or methods used to address missingness. Without these details, it is not possible to evaluate whether the primary comparison followed the randomized allocation or how incomplete data may have affected the estimate.

The primary endpoint covers more than one post-baseline time point, and multiple secondary outcomes are listed. The record does not report how multiplicity was handled, whether outcomes were prioritized beyond the designation of a primary outcome, or whether a statistical analysis plan specified the tests. Triple masking is recorded, but the roles masked are not described. The registry record also does not give further eligibility criteria, participant characteristics, adherence information, or treatment discontinuation details.

The safety record gives at-risk group sizes and zero event counts but does not describe event definitions, ascertainment, or safety follow-up duration. These omissions constrain interpretation of the counts. The record’s planning illustration is not the trial’s own design justification, and its numerical outputs and underlying observed effect are not reported. Taken together, these limitations mean the design can be described, but the primary comparative outcome and its robustness cannot be independently assessed from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Gulf War Illness Inflammation Reduction Trial — NCT02506192.
• Registry record last updated 2024-12-10; status last verified 2024-11.
• Results first posted 2023-12-06.
• 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 Gulf War Illness Inflammation Reduction Trial is recorded as a completed, randomized, triple-masked, parallel Phase 2 trial with an enrollment of 83. It compared modified-release prednisone with placebo in veterans with Gulf War Illness. The primary endpoint was change from baseline in the Veterans RAND 36-Item Health Survey Physical Component Summary score at 8 and 16 weeks.

The registry record lists secondary outcomes for pain, fatigue, cognitive failures, mental component summary score, and peripheral blood biomarkers. It records 42 participants at risk in the treatment group and 41 in the placebo group, with zero serious adverse events, zero other adverse events, and zero deaths in each group. Numerical primary-outcome results and detailed analysis methods are not reported in the registry record.