BackgroundGulf War illness (GWI) is a deployment-related chronic multisymptom illness impacting the health-related quality of life (HRQOL) of many U.S. Military Veterans of the 1990–91 Gulf War. A proinflammatory blood biomarker fingerprint was discovered in our initial study of GWI. This led to the hypothesis that chronic inflammation is a component of GWI pathophysiology.ObjectivesThe GWI inflammation hypothesis was tested in this Phase 2 randomized controlled trial (RCT) by measuring the effects of an anti-inflammatory drug and placebo on the HRQOL of Veterans with GWI. The trial is registered at ClinicalTrials.gov, Identifier: NCT02506192.RCT design and methodsGulf War Veterans meeting the Kansas case definition for GWI were randomized to receive either 10 mg modified-release prednisone or matching placebo. The Veterans RAND 36-Item Health Survey was used to assess HRQOL. The primary outcome was a change from baseline in the physical component summary (PCS) score, a measure of physical functioning and symptoms. A PCS increase indicates improved physical HRQOL.ResultsFor subjects with a baseline PCS <40, there was a 15.2% increase in the mean PCS score from 32.9±6.0 at baseline to 37.9±9.0 after 8 weeks on modified-release prednisone. Paired t-test analysis determined the change was statistically significant (p = 0.004). Eight weeks after cessation of the treatment, the mean PCS score declined to 32.7±5.8.ConclusionsThe prednisone-associated improvement in physical HRQOL supports the GWI inflammation hypothesis. Determining the efficacy of prednisone as a treatment for GWI will require a Phase 3 RCT.