Summary
Background: Several studies have reported on extensive two-way overlaps found among chronic fatigue syndrome (CFS), fibromyalgia syndrome (FMS) and multiple chemical sensitivity syndrome (MCS) but none have yet reported on the overlap of all three. This study assesses the prevalence of pure MCS, MCS-CFS, MCS-FMS and the overlap of all three among 100 consecutive new patients evaluated for MCS in a private practice specializing in occupational and environmental medicine.
Methods: Sixty-eight females and 32 males diagnosed with MCS-based on a medical history of multiple chronic symptoms in multiple organs triggered by multiple chemical exposures at or below previously tolerated levels-were also evaluated for CFS and FMS using the diagnostic criteria of the US Centers for Disease Control and the American College of Rheumatology, respectively.
Results: Eighty-eight percent of the 100 MCS patients met criteria for CFS, 49% met criteria for FMS, and 47% met both. Slightly more male than female MCS patients had CFS: 91% vs. 87%; while FMS was more than twice as common among female MCS patients: 59% vs. 28%. The majority of women, 56%, met criteria for all three disorders, and an additional 31% had both MCS and CFS. This pattern was reversed in men, only 28% of whom had all three, compared to 63% with MCS and CFS but no FMS. MCS alone was diagnosed in only 10% of the women and 9% of the men. Even rarer was the overlap of MCS and FMS without any CFS, found in just 2 women.
Conclusions: At least in this clinic population, MCS seldom occurs alone. The enormous range of diagnostic overlaps reported here and in previous studies of various overlaps among CFS, FMS and MCS highlights the need to screen for all three disorders in studies of any one and to report results in these terms. We recommend this be made standard practice in both clinical settings and research protocols.
Additional information
Notes on contributors
Albert Donnay
Grace Ziem maintains a private practice specializing in chemical injury and is the co-founder of MCS Referral & Resources, Inc.