ME/CFS is hetergeneous
This study found that although there is a wide variation in experience among the ME/CFS patient population, it does not differ significantly across different clinics. According to the authors “this suggests that expert clinicans are recognizing the same clinical entity, albeit one that is far from homogeneous.”
SUMMARY
- This study aimed to assess whether different clinical practices across seven U.S. specialty clinics lead to variations in the identification of ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) characteristics.
- Researchers utilized standardized questionnaires and data collection methods to compare patient characteristics and clinical features across these clinics.
- The results showed that despite slight statistical differences in demographic and clinical characteristics across sites, there were no clinically significant differences in the presentation of ME/CFS symptoms and functions among the clinics.
- This suggests that different clinical practices do not lead to significant variations in how ME/CFS is identified and managed among specialists.
- The study confirmed a wide range of symptom severity and functional impairment among ME/CFS patients, highlighting the inherent heterogeneity of the disease. All clinics reported a broad distribution in symptom scores and health measures.
- The study also examined the use of different case definitions for ME/CFS and found varying proportions of patients meeting each criterion across clinics, indicating that the choice of case definition can influence disease recognition and research outcomes.
DEFINITIONS
Case Definition: A set of standard criteria for determining whether a person has a particular disease or condition, used in research and clinical diagnostics to ensure consistency across studies and treatments.
Functional Impairment: A decrease in a patient’s ability to perform daily activities due to the effects of a medical condition.
Heterogeneity: In medical research, this refers to the variation in disease presentation and progression among different individuals with the same diagnosis.
RESEARCH ABSTRACT
Background:
One of the goals of the Multi-site Clinical Assessment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (MCAM) study was to evaluate whether clinicians experienced in diagnosing and caring for patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) recognized the same clinical entity.
Methods:
We enrolled participants from seven specialty clinics in the United States. We used baseline data (n = 465) on standardized questions measuring general clinical characteristics, functional impairment, post-exertional malaise, fatigue, sleep, neurocognitive/autonomic symptoms, pain, and other symptoms to evaluate whether patient characteristics differed by clinic.
Results:
We found few statistically significant and no clinically significant differences between clinics in their patients’ standardized measures of ME/CFS symptoms and function. Strikingly, patients in each clinic sample and overall showed a wide distribution in all scores and measures.
Conclusions:
Illness heterogeneity may be an inherent feature of ME/CFS. Presenting research data in scatter plots or histograms will help clarify the challenge. Relying on case–control study designs without subgrouping or stratification of ME/CFS illness characteristics may limit the reproducibility of research findings and could obscure underlying mechanisms.
Read full study:
Heterogeneity in Measures of Illness among Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Is Not Explained by Clinical Practice: A Study in Seven U.S. Specialty Clinics, by by Elizabeth R Unger et al in
J. Clin. Med. 2024, 13, 1369. [doi.org/10.3390/jcm13051369]
Read ME Research UK’s overview:
Disease heterogeneity among people with ME/CFS
Although a lack of variation between clinics was identified, the participants within each clinic – and in the overall sample – showed a wide distribution in scores and measures, indicating overall disease heterogeneity.
