Meredyth Evans

What is Fatigue? Pathological and Nonpathological Fatigue

Aid in understanding issues surrounding the construct validity of fatigue including the distinction between pathological versus nonpathological fatigue. Fatigue is a universal symptom reported by individuals in the general population as well as by those suffering from different medical and psychological illnesses, including cancer, multiple sclerosis, chronic fatigue syndrome, depression, and anxiety. Chronic fatigue is a significant problem in many primary care settings, and the debilitating and prolonged nature of fatigue can pose significant economic consequences for society. Researchers have struggled to better assess and understand the etiology and classification of fatigue within different illness groups.

Measuring substantial reductions in functioning in patients with chronic fatigue syndrome

Purpose. All the major current case definitions for chronic fatigue syndrome (CFS) specify substantial reductions in previous levels of occupational, educational, social, or personal activities to meet criteria. Difficulties have been encountered in operationalizing ‘substantial reductions.’ For example, the Medical Outcomes Study Short Form-36 Health Survey (SF-36) has been used to determine whether individuals met the CFS disability criterion. However, previous methods of using the SF-36 have been prone to including people without substantial reductions in key areas of physical functioning when diagnosing CFS. This study sought to empirically identify the most appropriate SF-36 subscales for measuring substantial reductions in patients with CFS. Method. The SF-36 was administered to two samples of patients with CFS: one recruited from tertiary care and the other a community-based sample; as well as a non-fatigued control group. Receiver operating characteristics were used to determine the optimal cutoff scores for identifying patients with CFS. Results. The SF-36 Role-Emotional subscale had the worst sensitivity and specificity, whereas the Vitality, Role-Physical, and Social Functioning subscales had the best sensitivity and specificity. Conclusion. Based on the evidence from this study, the potential criteria for defining substantial reductions in functioning and diagnosing CFS is provided.

Contrasting chronic fatigue syndrome versus myalgic encephalomyelitis/chronic fatigue syndrome

Background: Much debate is transpiring regarding whether chronic fatigue syndrome (CFS) and myalgic encephalomyelitis (ME) are different illnesses. Several prior studies that compared the Fukuda et al. CFS criteria to the Canadian ME/CFS criteria found that the Canadian criteria identified patients with more functional impairments and greater physical, mental, and cognitive problems than those who met Fukuda et al. criteria. These samples were located in the Chicago metropolitan area, so the results could not be generalized to other locations. In addition, past studies used a symptom questionnaire that was not specifically developed to tap the Canadian criteria. Purpose: The present comparative study of CFS and ME/CFS criteria was intended to correct the limitations of prior studies. Methods: This article used data from three distinct samples to compare patients who met criteria for the ME/CFS Canadian clinical case definition to those who met the Fukuda et al. CFS case definition. Results: Findings indicated that fewer individuals met the Canadian criteria than the Fukuda et al. criteria. Those who met the Canadian criteria evidenced more severe symptoms and physical functioning impairment. Conclusions: Future research should continue to compare existing case definitions and determine which criteria best select for this illness.

Contrasting Case Definitions for Chronic Fatigue Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Myalgic Encephalomyelitis

This article uses data from patients recruited using the 1994 case definition of chronic fatigue syndrome (CFS) to contrast those meeting criteria for the Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS) Canadian case definition with those that did not meet these criteria. The study also contrasts those meeting criteria for Myalgic Encephalomyelitis (ME) based on criteria from Ramsay and other theorists with those that did not meet the ME criteria. The ME/CFS case definition criteria identified a subset of patients with more functional impairments and physical, mental, and cognitive problems than the subset not meeting these criteria. The ME subset had more functional impairments, and more severe physical and cognitive symptoms than the subset not meeting ME criteria. When applied to a population meeting the 1994 CFS case definition, both ME/CFS and ME criteria appear to select a more severe subset of patients.

Chronic fatigue syndrome and myalgic encephalomyelitis: towards an empirical case definition

Current case definitions of myalgic encephalomyelitis and chronic fatigue syndrome (CFS) have been based on consensus methods, but empirical methods could be used to identify core symptoms and thereby improve the reliability. In the present study, several methods (i.e. continuous scores of symptoms, theoretically and empirically derived cut off scores of symptoms) were used to identify core symptoms best differentiating patients from controls. In addition, data mining with decision trees was conducted. Our study found a small number of core symptoms that have good sensitivity and specificity, and these included fatigue, post-exertional malaise, a neurocognitive symptom, and unrefreshing sleep. Outcomes from these analyses suggest that using empirically selected symptoms can help guide the creation of a more reliable case definition.

Test-Retest Reliability of the DePaul Symptom Questionnaire.

Background: The DePaul Symptom Questionnaire (DSQ) was developed to provide a structured approach for collecting standardized symptomatology and health history information to allow researchers and clinicians to determine whether a patient meets the diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), myalgic encephalomyelitis (ME), and/or chronic fatigue syndrome (CFS). Purpose: The purpose of this study was to examine the test–retest reliability of the DSQ. Methods: Test–retest reliability of the measure was examined with a sample of 26 adults self-identifying as having either ME/CFS, ME, and/or CFS and 25 adults who did not self-identify as having these illnesses and were otherwise healthy controls. Results: Overall, the majority of items on the DSQ exhibited good to excellent test–retest reliability, with Pearsons or kappa correlation coefficients that were 0.70 or higher. Conclusions: Thus, the present study suggests that the DSQ is a reliable diagnostic measure that can provide a standardized way of examining illness constructs and symptomatology among patients who identify as having ME/CFS, ME, and/or CFS.

Examining case definition criteria for chronic fatigue syndrome and myalgic encephalomyelitis

Background: Considerable controversy has transpired regarding the core features of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Current case definitions differ in the number and types of symptoms required. This ambiguity impedes the search for biological markers and effective treatments. Purpose: This study sought to empirically operationalize symptom criteria and identify which symptoms best characterize the illness. Methods: Patients (n = 236) and controls (n = 86) completed the DePaul Symptom Questionnaire, rating the frequency and severity of 54 symptoms. Responses were compared to determine the threshold of frequency/severity ratings that best distinguished patients from controls. A Classification and Regression Tree (CART) algorithm was used to identify the combination of symptoms that most accurately classified patients and controls. Results: A third of controls met the symptom criteria of a common CFS case definition when just symptom presence was required; however, when frequency/severity requirements were raised, only 5% met the criteria. Employing these higher frequency/severity requirements, the CART algorithm identified three symptoms that accurately classified 95.4% of participants as patient or control: fatigue/extreme tiredness, inability to focus on multiple things simultaneously, and experiencing a dead/heavy feeling after starting to exercise. Conclusions: Minimum frequency/severity thresholds should be specified in symptom criteria to reduce the likelihood of misclassification. Future research should continue to seek empirical support of the core symptoms of ME and CFS to further progress the search for biological markers and treatments.

Energy Conservation/Envelope Theory Interventions to Help Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Objectives: Treatment approaches for patients with chronic fatigue syndrome (CFS), Myalgic Encephalomyelitis (ME) and Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS) have been controversial. This paper provides the theoretical and conceptual background for the Energy Envelope Theory to assist patients and reviews evidence of its treatment efficacy. Methods: Over a 15-year period, efforts were directed to develop a non-pharmacologic intervention that endeavored to help patients to self-monitor and self-regulate energy expenditures and learn to pace activities and stay within their energy envelope. Conclusions: Studies show that the energy envelope approach, which involves rehabilitation methods, helps patients pace activities and manage symptoms and can significantly improve their quality of life.

Cognitive impairments associated with CFS and POTS.

Chronic fatigue syndrome (CFS) is characterized by fatigue, sleep dysfunction, and cognitive deficits (Fukuda et al., 1994). Research surrounding cognitive functioning among patients with CFS has found difficulty with memory, attention, and information processing. A similar disorder, postural tachycardia syndrome (POTS), is characterized by increased heart rate, fatigue, and mental cloudiness (Raj et al., 2009). Potential implications of cognitive deficits for patients with CFS and/or POTS are discussed, including difficulties with school and/or employment. A few biological theories (i.e., kindling, impairments in the central nervous system, and difficulty with blood flow) have emerged as potential explanations for the cognitive deficits reported in both CFS and POTS Future research should continue to examine possible explanations for cognitive impairments in CFS and POTS, and ultimately use this information to try and reduce cognitive impairments for these patients.

Myalgic Encephalomyelitis Case Definitions

This article reviews a Myalgic Encephalomyelitis (ME) case definition based on criteria offered over the past five decades. The current paper looks to review case definitions for ME based on Ramsay’s definition [41], the “London” criteria [45], Hyde’s Nightingale definition [16], and Goudsmit et al.’s criteria [11]. In general, these theorists have argued that ME is now defined differently than chronic fatigue syndrome because ME involves an acute onset, postexertional malaise and neurocognitive problems, and fatigue is not a major criteria. We will compare these theorists to the recently published International Consensus Criteria for Myalgic Encephalomyelitis [3]. We will also attempt to consolidate aspects of different current definitions in order to suggest possible core features of ME. This article will also recommend the importance of providing explicit, objective criteria on specific key symptoms. In addition, structured interview schedules along with specific medical tests are recommended to assure this illness is assessed in a consistent way across settings. It is hoped these developments will lead to increased reliability of the ME case definition, as well as more frequent use of these criteria by investigators.