Comparison of patients with chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivities.
Buchwald, D, Garrity, D · Archives of internal medicine · 1994
Quick Summary
This study compared 90 patients with three conditions that cause fatigue and other symptoms: ME/CFS, fibromyalgia, and multiple chemical sensitivities. The researchers found that these three conditions are very similar in many ways—patients often report overlapping symptoms, and many people meet the criteria for more than one condition. All three groups used a lot of healthcare services, visiting doctors about 22-40 times per year on average.
Why It Matters
This study provides important evidence that ME/CFS, fibromyalgia, and multiple chemical sensitivities may share common underlying biological or pathophysiological mechanisms rather than being completely distinct diseases. Understanding these overlaps helps patients and clinicians recognize that having multiple diagnoses is common and may inform future research into whether these conditions share a common cause.
Observed Findings
Patients with CFS and FM frequently reported symptoms compatible with MCS.
70% of fibromyalgia patients met diagnostic criteria for CFS; 30% of MCS patients met CFS criteria.
The three groups were similar in demographic characteristics and symptom prevalence.
Average healthcare provider visits in the prior year: CFS 22.1, FM 39.7, MCS 23.3 visits.
Health locus of control did not differ significantly among the three patient groups.
Inferred Conclusions
Demographic and clinical factors do not clearly distinguish patients with CFS, FM, and MCS, suggesting possible shared pathophysiology.
Symptoms typical of each disorder are prevalent in the other two conditions, indicating substantial overlap in clinical presentation.
These conditions may represent different clinical manifestations of a common underlying process rather than entirely separate diseases.
Remaining Questions
What are the biological mechanisms that explain the symptom overlap among these three conditions?
Do patients with multiple diagnoses have different prognoses or treatment responses compared to those with single diagnoses?
What This Study Does Not Prove
This cross-sectional design cannot establish causation or determine whether symptom overlap reflects shared etiology or simply represents different manifestations of a single process. The study does not prove that these conditions are the same disease or explain why some patients meet criteria for multiple conditions while others do not. Small sample sizes and recruitment from specialty clinics may limit generalizability to broader patient populations.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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