Subtyping Patients with Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) By Course of Illness

Past research has subtyped patients with Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) according to factors related to illness onset, illness duration, and age. However, no classification system fully accounts for the wide range of symptom severity, functional disability, progression, and prognosis seen among patients. This study examined whether illness trajectories among individuals with CFS were predictive of different levels of symptomology, functional disability, and energy expenditure. Of the participants (N=541), the majority described their illness as Fluctuating (59.7%), with 15.9% Constantly Getting Worse, 14.1% Persisting, 8.5% Relapsing and Remitting, and 1.9% Constantly Getting Better. The illness courses were associated with significant differences in symptomology on select domains of the DSQ, functioning on select subscales of the SF-36, and on overall levels of energy expenditure. The significant symptomatic and functional differences between groups suggest that subtyping patients with CFS according to illness course is a promising method for creating more homogeneous groups of patients

Operationalizing Substantial Reduction in Functioning Among Young Adults with Chronic Fatigue Syndrome

Purpose Chronic fatigue syndrome and myalgic encephalomyelitis are fatiguing illnesses that often result in long-term impairment in daily functioning. In reviewing case definitions, Thrope et al. (Fatigue 4(3):175–188, 2016) noted that the vast majority of case definitions used to describe these illnesses list a “substantial reduction” in activities as a required feature for diagnosis. However, there is no consensus on how to best operationalize the criterion of substantial reduction. Method The present study used a series of receiver operating curve (ROC) analyses to explore the use of the Medical Outcomes Study Short-Form-36 Health Survey (SF-36), designed by Ware and Shelbourne for operationalizing the substantial reduction criterion in a young adult population (18–29 years old). We compared the sensitivity and specificity of various cutoff scores for the SF-36 subscales and assessed their usefulness in discriminating between a group of young adults with a known diagnosis of chronic fatigue syndrome or myalgic encephalomyelitis (n = 98) versus those without that diagnosis (n = 272). Results The four top performing subscales and their associated cutoffs were determined: Physical Functioning ≤ 80, General Health ≤ 47, Role Physical ≤ 25, and Social Functioning ≤ 50. Used in combination, these four cutoff scores were shown to reliably discriminate between the patients and controls in our sample of young adults. Conclusion The implications of these findings for employing the substantial reduction criterion in both clinical and research settings are discussed

Assessing current functioning as a measure of significant reduction in activity level

Background Myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) have case definitions with varying criteria, but almost all criteria require an individual to have a substantial reduction in activity level. Unfortunately, a consensus has not been reached regarding what constitutes substantial reductions. One measure that has been used to measure substantial reduction is the Medical Outcomes Study Short Form-36 Health Survey (SF-36).[1] Purpose The current study examined the relationship between the SF-36, a measure of current functioning, and a self-report measure of the percent reduction in hours spent on activities. Results Findings indicated that select subscales of the SF-36 accurately measure significant reductions in functioning. Further, this measure significantly differentiates patients from controls. Conclusion Determining what constitutes a significant reduction in activity is difficult because it is subjective to the individual. However, certain subscales of the SF-36 could provide a uniform way to accurately measure and define substantial reductions in functioning