Gender differences in chronic fatigue syndrome

The title of this post matches the title of the paper published by Monica Faro and colleagues [1] (open-access here) and some potentially important data on "whether there are gender-related differences in CFS [Chronic Fatigue Syndrome], and to define a clinical phenotype in men."

Starting with the idea that the prevalence of CFS - a generic term covering a spectrum of conditions characterised by severe and debilitating fatigue among several other things - may have a gender skew towards females over males [2], Faro and colleagues set about looking at whether the presentation of CFS might also differ between males and females. I should perhaps back-up a little and highlight how the sex differences in CFS frequency might be somewhat clouded by the fact that quite a few diagnostic criteria systems are currently around for CFS (also called myalgic encephalomyelitis, ME) and that under-diagnosis of men cannot yet be discounted as contributing to any gender differences. Think autism and the perceived gender skew there as an example of potential under-diagnosis in action with another label in mind.

Based on the analysis of over 1300 patients formally diagnosed with CFS (using the Fukuda 1994 definition), 119 (9%) of the cohort were described as male. Following the administration of a clinical interview "conducted by 2 specialized internists in the diagnosis of the disease" among other things, researchers reported a few interesting details. First, men in general seemed to be diagnosed slightly earlier than women. It wasn't a stark difference measured in decades for example, but a difference of on average, 4-5 years. Further: "Widespread pain, muscle spasms, dizziness, sexual dysfunction, Raynaud's phenomenon, morning stiffness, migratory arthralgias, drug and metals allergy, and facial oedema were less frequent in men." Fibromyalgia as "defined by the criteria of the ACR" was also reported to be less frequent in men than women (29% vs 58% respectively). Also of interest was the suggestion that: "The most common triggering factor was an infection" where men were more likely than women to relate their symptoms to such a factor.

These are interesting findings that add an extra dimension to discussions about CFS with a view to a possible role for gender differences. Obviously one has to be a little guarded about making too many sweeping generalisations that for example, CFS is a 'different condition' for men and women because we don't really have a great deal of evidence to back up such a claim. Insofar as the possibility that men are diagnosed earlier than women, this could point to a number of things. Either this is reflective of an earlier onset of the illness in men or that women find it more difficult to get diagnosed with CFS. I'd be interested to see how this variable pans out as and when more research in this area is forthcoming.

Music: The Calling - Wherever You Will Go.

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[1] Faro M. et al. Gender differences in chronic fatigue syndrome. Reumatol Clin. 2015 Jul 16. pii: S1699-258X(15)00081-9.

[2] Líndal E. et al. The prevalence of chronic fatigue syndrome in Iceland - a national comparison by gender drawing on four different criteria. Nord J Psychiatry. 2002;56(4):273-7.

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Faro M, Sàez-Francás N, Castro-Marrero J, Aliste L, Fernández de Sevilla T, & Alegre J (2015). Gender differences in chronic fatigue syndrome. Reumatologia clinica PMID: 26190206