E2 ModerateModerate confidencePEM not requiredCase-ControlPeer-reviewedReviewed
Standard · 3 min
The number of existing functional somatic syndromes (FSSs) is an important risk factor for new, different FSSs.
Warren, John W, Langenberg, Patricia, Clauw, Daniel J · Journal of psychosomatic research · 2013 · DOI
Quick Summary
This study found that people who have multiple overlapping illnesses like fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and others are more likely to develop additional new conditions over time. The more conditions someone already had, the higher their risk of developing a new one. This suggests these conditions may share common underlying causes rather than being completely separate diseases.
Why It Matters
For ME/CFS patients, this research demonstrates that having CFS alongside other conditions like fibromyalgia or IBS is not coincidental but reflects underlying biological connections between these syndromes. Understanding this polysyndromic relationship may help guide future research toward identifying shared disease mechanisms that could lead to more effective treatments addressing multiple conditions simultaneously.
Observed Findings
Incidence of new FSSs increased proportionally with the number of pre-existing FSSs in both case and control groups
Multiple antecedent FSSs generated among the highest odds ratios for incident fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome
The association between FSS count and new FSS development persisted after controlling for individual syndromes, published correlates, and demographic variables
Fibromyalgia, chronic fatigue syndrome, and IBS showed the strongest associations with antecedent FSS burden
Inferred Conclusions
Functional somatic syndromes are linked through a polysyndromic phenotype rather than operating as independent conditions
The number of existing FSSs is among the strongest risk factors for developing additional FSSs, independent of other known risk factors
Research seeking common pathogenic mechanisms should prioritize individuals with multiple FSSs, while research seeking syndrome-specific mechanisms should focus on adults with single-FSS presentations
Remaining Questions
What is the biological mechanism underlying the polysyndromic phenotype observed across these FSSs?
Does the temporal sequence of FSS development follow predictable patterns, or does it vary among individuals?
What This Study Does Not Prove
This study does not establish causation—having one FSS does not necessarily cause another. The cross-sectional and case-control design cannot definitively identify whether a shared biological mechanism drives all FSSs or whether having one condition increases detection/reporting of others. The study also cannot identify what that common mechanism might be.
Tags
Symptom:Cognitive DysfunctionPainFatigue
Method Flag:PEM Not DefinedWeak Case DefinitionMixed Cohort
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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How much of the increased FSS incidence risk reflects true biological susceptibility versus increased symptom recognition and medical attention in multiply-affected individuals?
Are there genetic, immune, neurological, or other pathophysiological factors shared across FSSs that could explain this clustering?