THERE ARE NO SUBSETS IN CFS.....Virtually every researcher I know of would love to find subsets...because then you would have discrete types of patients that they can study without the 'other types' of patients confounding their results....
...
It all comes down to research. Until you can prove subsets with research studies everything else is just talk! You'll never get someone to study a 'subset' until they can prove it exists. Because no one has done that... there is no science showing verifiable subsets and until there is its all just going to be 'CFS'.
Actually, there have been a couple of methods of determining subsets proposed. Nobody has bothered to try to replicate them so we don't know if they're verifiable, but there are indeed possibilities. There's no reason under the sun why we shouldn't be campaigning to replicate some of these studies:
Kerr
et al. have written three articles on their genomics approach
Kerr JR, Burke B, Petty R, Gough J, Fear D, Mattey DL, Axford JS, Dalgleish AG, Nutt DJ. "Seven genomic subtypes of chronic fatigue syndrome/myalgic encephalomyelitis: a detailed analysis of gene networks and clinical phenotypes." J Clin Pathol. 2008 Jun;61(6):730-9. Epub 2007 Dec 5. PMID: 18057078
Kerr JR. "Gene profiling of patients with chronic fatigue syndrome/myalgic encephalomyelitis." Curr Rheumatol Rep. 2008 Dec;10(6):482-91. PMID: 19007540
Abstract: Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a multisystem disease, the pathogenesis of which remains undetermined. Following two microarray studies, we reported the differential expression of 88 human genes in patients with CFS; 85 of these genes were upregulated and 3 were downregulated. The top functional categories of these 88 genes were hematologic disease and function, immunologic disease and function, cancer, cell death, immune response, and infection. Clustering of quantitative polymerase chain reaction data from CFS/ME patients revealed seven subtypes with distinct differences in Short Form (SF)-36 scores, clinical phenotypes, and severity. Gene signatures in each subtype implicate five human genes as possible targets for specific therapy. Development of a diagnostic test for subtype status is now a priority. The possibility that these subtypes represent individual host responses to particular microbial infections is being investigated and may provide another route to specific therapies for CFS patients.
Zhang L, Gough J, Christmas D, Mattey DL, Richards SC, Main J, Enlander D, Honeybourne D, Ayres JG, Nutt DJ, Kerr JR. "Microbial infections in eight genomic subtypes of chronic fatigue syndrome/myalgic encephalomyelitis." J Clin Pathol. 2010 Feb;63(2):156-64. Epub 2009 Dec 2. PMID: 19955554
BACKGROUND: The authors have previously reported genomic subtypes of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) based on expression of 88 human genes.
AIM: To attempt to reproduce these findings, determine the specificity of this signature to CFS/ME, and test for associations between CFS/ME subtype and infection.
METHODS: Expression levels of 88 human genes were determined in blood of 62 new patients with idiopathic CFS/ME (according to Fukuda criteria), six patients with Q-fever-associated CFS/ME from the Birmingham Q-fever outbreak (according to Fukuda criteria), 14 patients with endogenous depression (according to DSM-IV criteria) and 29 normal blood donors.
RESULTS: In patients with CFS/ME, differential expression was confirmed for all 88 genes. Q-CFS/ME had similar patterns of gene expression to idiopathic CFS/ME. Gene expression in patients with endogenous depression was similar to that in the normal controls, except for upregulation of five genes (APP, CREBBP, GNAS, PDCD2 and PDCD6). Clustering of combined gene data in CFS/ME patients for this and the authors' previous study (117 CFS/ME patients) revealed genomic subtypes with distinct differences in SF36 scores, clinical phenotypes, severity and geographical distribution. Antibody testing for Epstein-Barr virus, enterovirus, Coxiella burnetii and parvovirus B19 revealed evidence of subtype-specific relationships for Epstein-Barr virus and enterovirus, the two most common infectious triggers of CFS/ME.
CONCLUSIONS: This study confirms the involvement of these genes in CFS/ME.
This does go along with Dowsett's assertion that only enteroviral infection counts as true ME and other kinds of infections leading to similar symptoms are different diseases. I don't have a huge issue with whether we say different diseases or different subtypes (although different subtypes seems more convenient to me among the community of those of us with long-lasting disease and PEM) as long as we make some progress towards
understanding and treating our disease(s).
Then you have, of course, Natleson
et al.'s symptom-based analysis (and Kerr
et al. are saying their findings correlate with symptoms so we may be looking at some of the same sets actually).
Janal MN, Ciccone DS, Natelson BH. "Sub-typing CFS patients on the basis of 'minor' symptoms." Biol Psychol. 2006 Aug;73(2):124-31. Epub 2006 Feb 10. PMID: 16473456
Fatigue Research Center and Department of Psychiatry, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07101, USA.
Abstract
The diagnosis of chronic fatigue syndrome (CFS), an illness characterized by medically unexplained fatigue, depends on a clinical case definition representing one or more pathophysiological mechanisms. To prepare for studies of these mechanisms, this study sought to identify subtypes of CFS. In 161 women meeting 1994 criteria for CFS, principal components analysis of the 10 'minor' symptoms of CFS produced three factors interpreted to indicate musculoskeletal, infectious and neurological subtypes. Extreme scores on one or more of these factors characterized about 2/3 of the sample. Those characterized by the neurological factor were at increased risk of reduced scores on cognitive tests requiring attention, working memory, long-term memory or rapid performance. In addition, the neurological subtype was associated with reduced levels of function. Those characterized by the musculoskeletal factor were at increased risk for the diagnosis of fibromyalgia (chronic widespread pain and mechanical allodynia) and reduced physical function. Those characterized by the infectious factor were less likely to evidence co-occurring fibromyalgia, and showed lesser risk of functional impairment. The prevalence of disability was increased in those with the highest scores on any of the subtypes, as well as in those with high scores on multiple factors. Depression and anxiety, while frequently present, were not more prevalent in any particular subtype, and did not increase with the severity of specific symptom reports. Results suggest that subtypes of CFS may be identified from reports of the minor diagnostic symptoms, and that these subtypes demonstrate construct validity.
Then, of course, you have this little matter of
the Fukuda mandate:
http://myalgic-encephalomyelitis.com/Fukuda_Criteria2.html
In formal studies, cases of the chronic fatigue syndrome and idiopathic chronic fatigue should be subgrouped before analysis or stratified during analysis by the presence or absence of essential variables, which should be routinely established in all studies. Further subgrouping by optional variables can be done according to specific research interests.
Essential Subgrouping Variables
1. Any clinically important coexisting medical or neuropsychiatric condition that does not explain the chronic fatigue. The presence or absence, classification, and timing of onset of neuropsychiatric conditions should be established using published or freely available instruments, such as the Composite International Diagnostic Instrument (34), the National Institute of Mental Health Diagnostic Interview Schedule (35), and the Structured Clinical Interview for DSM-III(R) (36)
2. Current level of fatigue, including subjective or performance aspects. These levels should be measured using published or widely available instruments. Examples include instruments by Schwartz and colJeagues (37), Piper and colleagues (38), rupp and colleagues (39), Chalder and colleagues (40), and Vercoulen and colleagues (41).
3. Total duration of fatigue.
4. Current level of overall functional performance as measured by published or widely available instruments, such as the Medical Outcomes Study Short Form 36 (42) and the Sickness Impact Profile (43).
Optional Subgrouping Variables
Examples of optional variables include:
1. Epidemiologic or laboratory features of specific interest to researchers. Examples include laboratory documentation or self- reported history of an infectious illness at the onset of fatiguing illness, a history of rapid onset of illness, or the presence or level of a pal1icular immunologic marker.
2. Measurements of physical function quantified by means such as treadmill testing or motion-sensing devices.
Please notice that presence/absence of psychiatric and medical conditions is
mandatory, as is level and length of fatigue and
level of functionality.
Having followed the
MANDATE of Fukuda would have saved us a lot of grief.
Why is no one insisting on this at least?
Jennifer, please bring this up with the CAA board ASAP (stratification mandate of Fukuda, and the subset possibilities that exist and require replication studies).
That the CDC would not follow their official definition (and not be asking/reminding outside research community to do this as well, and including it prominently as part of the definition) is outrageous and unconscionable. This goes for use of Reeves inclusion crieteria, too. The best definition approach is to switch to something which more properly defines ME/CFS, but the CDC should AT LEAST follow their own official definition!!!!!
Of course, we can try to inform this stratification info with later research (such as that the Chalder scale is inappropriate for severe lengthy disease, and maybe with other items needed to add to the mandatory list, etc.) In fact, Fukuda did say later research should be informative:
These research tools will evolve as new knowledge is gained. Second, none of the provisions in these guidelines, especially the definition of idiopathic chronic fatigue and subgroups of the chronic fatigue syndrome, establish new clinical entities. Rather, these definitions were designed to facilitate comparative studies. Finally, general reference to these guidelines should not be substituted for clear and detailed methodologic descriptions when reporting studies. The lack of detailed information about the sources, selection, and evaluation of study participants (including controls), case definitions, and measurement techniques in reports of chronic fatigue syndrome research has contributed substantially to our current difficulties in interpreting research findings.
Yet the CDC's website recommends the exact same set of tools as Fukuda did. There has seriously been no progress that they have noticed since 1994? No progress
at all in 18 years? Not even these?
Whistler T, Jones JF, Unger ER, Vernon SD. "Exercise responsive genes measured in peripheral blood of women with chronic fatigue syndrome and matched control subjects." BMC Physiol. 2005 Mar 24;5(1):5. PMID: 1579042
Viral Exanthems and Herpesvirus Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333
Exercise-responsive genes differed between CFS patients and controls. These were in genes classified in chromatin and nucleosome assembly, cytoplasmic vesicles, membrane transport, and G protein-coupled receptor ontologies. Differences in ion transport and ion channel activity were evident at baseline and were exaggerated after exercise, as evidenced by greater numbers of differentially expressed genes in these molecular functions.
CONCLUSION: These results highlight the potential use of an exercise challenge combined with microarray gene expression analysis in identifying gene ontologies associated with CFS.
Cameron B, Galbraith S, Zhang Y, Davenport T, Vollmer-Conna U, Wakefield D, Hickie I, Dunsmuir W,
Whistler T, Vernon S, Reeves WC, Lloyd AR; Dubbo Infection Outcomes Study. "Gene expression correlates of postinfective fatigue syndrome after infectious mononucleosis." J Infect Dis. 2007 Jul 1;196(1):56-66. Epub 2007 May 24. PMID: 17538884
School of Medical Sciences, University of New South Wales, Sydney, Australia.
RESULTS: Differential expression of 733 genes was identified when samples collected early during the illness and at the late (recovered) time point were compared. Of these genes, 234 were found to be significantly correlated with the reported severity of the fatigue symptom factor, and 180 were found to be correlated with the musculoskeletal pain symptom factor. Validation by analysis of the longitudinal expression pattern revealed 35 genes for which changes in expression were consistent with the illness course. These genes included several that are involved in signal transduction pathways, metal ion binding, and ion channel activity.
CONCLUSIONS: Gene expression correlates of the cardinal symptoms of PIFS after IM have been identified. Further studies of these gene products may help to elucidate the pathogenesis of PIFS.
Sorensen B, Jones JF, Vernon SD, Rajeevan MS. "Transcriptional control of complement activation in an exercise model of chronic fatigue syndrome." Mol Med. 2009 Jan-Feb;15(1-2):34-42. Epub 2008 Nov 10. PMID: 19015737
Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, United States of America.
In conclusion, lectin pathway responded to exercise differentially in CFS than in control subjects. MASP2 down-regulation may act as an antiinflammatory acute-phase response in healthy subjects, whereas its elevated level may account for increased C4a and inflammation-mediated postexertional malaise in CFS subjects.
And we must insist upon replication of existing proposed subgroups and further development of subgroups as well. This is the only way we are going to get proper treatment for individuals.