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Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington (DC): National Academies Press (US); 2015 Feb 10.

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Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness.

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CDisability in ME/CFS

Several ME/CFS symptoms may contribute to impairment or disability, including fatigue, cognitive dysfunction, pain, sleep disturbance, post-exertional malaise (PEM), and secondary depression or anxiety (Andersen et al., 2004; Tiersky et al., 2001).1 This appendix presents the Social Security Administration's (SSA's) current guidelines for evaluating disability in ME/CFS patients and summarizes research to date in assessing disability and impairment in both children and adults with ME/CFS.

SSA GUIDELINES FOR EVALUATING DISABILITY

In April 2014, SSA issued updated guidelines for evaluating disability claims involving ME/CFS. Social Security Ruling (SSR 14-1p) provides guidance on how to develop evidence to establish that a person has a medically determinable impairment (MDI) of ME/CFS and explains how SSA evaluates disability claims and continuing disability reviews for ME/CFS under titles II and XVI of the Social Security Act. According to SSA, determination of an MDI includes a diagnosis of ME/CFS by a licensed physician using the Fukuda case definition, supported by specific medical evidence consisting of signs, symptoms, and laboratory findings (see Box C-1). Therefore, it is critical for health care providers to know what medical evidence is necessary and how to test for it in order for patients to receive disability status. It should be noted that the symptoms constituting this report's new diagnostic criteria, as well as the objective tests mentioned in Chapter 7 (tilt table test, cardiopulmonary exercise test [CPET], and neuropsychological testing), are already included in the current guidelines.

Box Icon

BOX C-1

Social Security Administration Evaluation of Disability. For the purposes of Social Security Disability evaluation, in addition to a diagnosis of ME/CFS that meets the Fukuda case definition, one or more of the following medical signs clinically documented (more...)

ASSESSING DISABILITY

This section reviews the literature regarding the role of impairment and disability in ME/CFS patients. While it stands to reason that many of the individual symptoms of ME/CFS can cause impairment, this is not the focus of this section; it is instead discussed in various sections throughout Chapters 4, 5, and 6.

Challenges and Limitations

Research to date illustrates the many challenges of assessing disability in adults with ME/CFS, an illness for which cause and cure are unknown. First, the often lengthy duration of time between symptom onset and diagnosis is estimated to be at least 1 year in 67 to 77 percent of patients and at least 5 years in 29 percent of patients (CFIDS Association of America, 2014; ProHealth, 2008). Thus, many people may be disabled for years before being identified as an ME/CFS patient. Second, compared with more current case definitions (Carruthers et al., 2003, 2011), the most commonly used case definition (Fukuda et al., 1994) identifies a more broadly defined patient population in which PEM, arguably a hallmark of ME/CFS, is not required for diagnosis. Thus, evidence of disability must correspond to the unique semiology of this broadly defined patient population. Third, disability, evidenced by the persistence of illness following optimal treatment, requires consensus regarding an optimal course of treatment. A lack of consensus regarding treatment efficacy persists in the research to date and further confounds efforts to assess disability status. Fourth, studies of recovery from ME/CFS vary widely as a result of the use of different case definitions in the study samples; differing definitions of “recovery”; the lack of temporal metrics of function obtained before, during, and after treatment; and the use of patients' subjective assessment of their own progression of illness and recovery (Cairns and Hotopf, 2005). The call for objective markers of impairment that correspond to the unique symptom complex of ME/CFS patients is prudent and indicated given the lack of consensus that persists in the research literature regarding assessment of recovery.

Impact on Daily Activities, Responsibilities, and Social Interactions

Daily activities, responsibilities, and social interactions—perhaps the most important of which are adults' ability to work and children's attendance and performance in school—can be an important indicator of disability and impairment (Schweitzer et al., 1995). Patients coping with the burden of disease will often reduce certain activities such as extracurricular school activities or social gatherings in order to fulfill these essential responsibilities. Thus, it is important to exercise caution in generalizing findings on work and school to a patient's overall function.

Impairment and Employment Status

A review of studies published between 1966 and 2004 examined the extent of work-related impairment and unemployment in ME/CFS (Taylor and Kielhofner, 2005). Studies were included if work-related impairment was a primary variable and individuals met any case definition for ME/CFS. Regarding work-related impairment, unemployment rates in 13 of 15 studies varied from 35 to 69 percent. Job loss ranged from 26 to 89 percent, which was consistent with job loss among those with other chronic illnesses. Decreased work performance also was consistently reported in the literature and was attributed to impairments of short-term memory and learning, decision making, attendance, and communication skills and increased dependence on coworkers to perform work duties, among other reasons. Studies in this review were based primarily on unstandardized self-report, and some data indicated that symptom severity was associated with inability to work.

A systematic review of studies published between 1988 and 2001 examined evidence in the literature relating impairment to employment status in those diagnosed with ME/CFS (Ross et al., 2002, 2004). Evidence of impairment was found to be substantially more prevalent in ME/CFS (40 percent of 1,830 patients) than in controls (12 percent), and 54 percent of ME/CFS patients reported being unemployed, compared with 9 percent of controls.

Impairment and School Activity

For children, adolescents, and young adults who are not yet engaged in full-time occupations, physical function, impairment, and disability are more appropriately evidenced by school attendance. Additionally, assessment of social, physical, emotional, psychosocial, and cognitive domains that reflect levels and quality of overall function in this age range are warranted.

In their epidemiological study of absence due to long-term sickness in U.K. schools, Dowsett and Colby (1997) examined the results of a 5-year retrospective survey of school principals and students in six school areas. They found that 42 percent of all medically certified long-term sickness-related absence was due to ME/CFS, a figure considerably higher than those absent due to cancers (23 percent), other illnesses (13 percent), and psychiatric or psychological problems (12 percent). Crawley and colleagues (2011) performed a clinical evaluation of schoolchildren ages 11-16 years enrolled in secondary schools in the Bath region of England and who had been absent for more than 20 percent of a 6-week term (n = 461). Of this high absence group, 6 percent were identified as having ME/CFS, confirming ME/CFS as a major cause of school absence. Only 11 percent of these children had previously been diagnosed with ME/CFS, indicating under-recognition of the illness.

Bell and colleagues (2001) completed a 13-year follow-up of 35 respondents who developed an illness suggestive of ME/CFS in children and adolescents between January 1984 and December 1987 in an isolated rural community in upstate New York. All of these individuals met the Fukuda definition retrospectively. The educational impact of the illness was correlated most closely with illness outcome, with those who missed the most school (up to 2 years) reporting the poorest recovery over time. Upon follow-up, 66 percent believed that their illness had an overall social effect on their life that varied from mild to severe. In general, the social effect paralleled the perceived illness outcome. Crawley and Sterne (2009) found that reduced school attendance among children with ME/CFS was associated most strongly with poor physical function, with more than 60 percent of the 211 children with ME/CFS in their sample attending only 2 days of school or less per week. Smith and colleagues (2003) found that adolescents with ME/CFS missed 57 days of school on average over a 6-month period. Severity of fatigue was highly associated with school absence.

Health care providers should not dismiss the lack of school attendance or participation in activities in these patients as merely school phobia or having overprotective parents. Further, pediatricians should assess the risk or existence of a disability in their patients ideally at their first visit and identify those who may benefit from services under the Individuals with Disabilities Education Act (IDEA). Pediatricians should be well informed about the process for referring children and adolescents with a disabling condition to early intervention programs in the community and explain the parents' right to have their children evaluated by a multidisciplinary team from the school or a state-designated agency (American Academy of Pediatrics, 1999).

Other Indicators of Impairment

A recent Norwegian study that surveyed ME patients as defined by the International Consensus Criteria for ME (ME-ICC) (Carruthers et al., 2011) attempted to characterize the burden of disease through self-report measures in lay terms (Bringsli et al., 2014). The authors found that 75 percent of those surveyed described their impairment as being housebound most of the time (leaving home only with careful planning) if not all of the time or being fully bedridden.

The Centers for Disease Control and Prevention's (CDC's) Multi-Site Study surveyed ME/CFS patients using the Short Form 36-Item Questionnaire of the Medical Outcomes Study (MOS) (SF-36) as an indicator of function (Unger, 2013). Preliminary data from this study show that patients scored under 40 on all measures except for “role emotional” and “mental health.” They scored particularly low (< 20) on “role physical” and “vitality.” These findings were consistent across sites.

A comparison of quality of life (QOL) characteristics in 25 children from the United Kingdom with ME/CFS (based on the Fukuda definition) and 23 age/gender/Tanner stage-matched healthy controls found QOL in the ME/CFS children to be profoundly reduced (Kennedy et al., 2010). Only 1 of 25 children with ME/CFS attended school full time, 48 percent attended school part time, and 32 percent received home tutoring. Children with ME/CFS scored substantially lower than controls on the global health item of the Child Health Questionnaire (CHQ), as well as most other items, including physical functioning, social limitations due to emotional and health limitations, pain and discomfort, mental health, self-esteem, general health perceptions, and family activities. Most notably, a comparison of scores on nine items of the CHQ revealed that the ME/CFS children scored lower than children with type 1 diabetes and asthma as well as healthy controls.

Similarly, Rowe and colleagues (2014) compared the self-reported health-related quality of life (HRQOL) of adolescents and young adults with ME/CFS with that of healthy controls as well as published results of HRQOL in other chronic pediatric conditions. Scores on all measures of HRQOL indicated worse function among those with ME/CFS compared with controls. The mean total score on the Pediatric Quality of Life Inventory (one of the tools used to measure HRQOL) for ME/CFS was lower than published scores for children with cystic fibrosis, eosinophilic gastrointestinal disorder, epilepsy, type 1 diabetes, sickle cell disease, and renal transplants and comparable to scores for children with pediatric fibromyalgia and paraplegic cerebral palsy (Ingerski et al., 2010; Varni et al., 2007).

Duration of Disability

The length of recovery time and effectiveness of treatment for ME/CFS have important implications for defining the duration of disability.

Recovery

A recent effort to define recovery in ME/CFS employed a systematic review of 22 studies in which recovery was defined operationally by reference to one or more of these domains: (1) premorbid functioning, (2) both fatigue and function, (3) fatigue (or related symptoms) alone, (4) function alone, and/or (5) brief global assessment (Adamowicz et al., 2014). The aim was to systematically review and evaluate the different definitions of recovery proposed in the ME/CFS literature and to offer recommendations for future research.

The brief global assessment was the most common outcome measure used to define recovery, although measures of recovery varied considerably among the studies. Overall, the review revealed widely varying estimates of recovery that ranged from 0 to 66 percent in intervention studies and 2.6 to 62 percent in naturalistic studies. The review found many inconsistencies across the literature which help explain the wide range of these estimates. First, the wide range can be explained in part by whether recovery was defined by single or multiple domains. Reports of high recovery rates typically were based on single-domain definitions of recovery (e.g., fatigue or function); use of multiple criteria (fatigue scores within the normal range, normal health perceptions, no physical or social disabilities, and no negative perceptions of fatigue) within the same cohort produced rates of recovery less than half of those reported using single-domain definitions. Second, the term “recovery” often included less than full restoration of health as reported by the patients, and typically it was based on limited assessment. Thus, the authors recommend that positive changes in illness status be referred to more precisely as “clinically significant improvement” to better differentiate between “recovery” (return to premorbid functioning) and “improvement” (positive change in health but not full restoration). Third, the majority of studies relied on patient self-reports and did not utilize more objective measures of recovery, such as return to work or school- or laboratory-based assessments. Consequently, it is difficult to know whether substantial recovery occurred.

In a response to the recommendations of Adamowicz and colleagues (2014), Twisk (2014) states that subjective measures cannot dispel the debate regarding identification of full or partial recovery from ME/CFS. Instead, he recommends objective measures to characterize the clinical status and function of a patient before, during, and after treatment interventions to ascertain partial or full recovery. Further, he asserts that accurate diagnosis is crucial to establish whether a patient has recovered, and that objective assessment must address the unique symptoms in accordance with the diagnosis, whether it be ME or CFS.

The challenge of defining recovery in ME/CFS is further supported by a study of long-term health, symptom, and disability outcomes in ME/CFS patients diagnosed 25 years ago compared with healthy controls (Brown et al., 2012). Twenty of the 25 patients in the study reported no longer having a diagnosis of ME/CFS. Compared with healthy controls, those who remitted from ME/CFS showed significantly more impairment on 21 of 23 outcomes. Likewise, compared with the 5 patients who maintained a diagnosis of ME/CFS, those who remitted from ME/CFS showed no difference on 17 outcomes of impairment. The results of this study suggest that over time, most ME/CFS patients will not maintain the diagnosis, but they will not fully recover and will still be symptomatic.

A systematic review by Taylor and Kielhofner (2005) examined employment status as an indicator of recovery. The review included three longitudinal studies that found little change in employment status over time (Bombardier and Buchwald, 1995; Tiersky et al., 2001; Vercoulen et al., 1996). A 5-year follow-up study by Andersen and colleagues (2004) found that work disability of ME/CFS patients, identified in accordance with the Fukuda definition, increased from 77 to 91 percent, indicating no evidence of recovery.

Treatment

Similar to the literature on treatment in ME/CFS patients, there is little evidence on the efficacy of interventions in ME/CFS patients with respect to function and disability.

The efficacy of cognitive-behavioral therapy (CBT) in improving cognitive function in ME/CFS patients is unclear. Knoop and colleagues (2007) found a decrease in self-reported cognitive impairment following CBT, yet ME/CFS patients did not differ from a support control group on results of the subscale of alertness behavior of the Sickness Impact Profile (SIP-ab). These results do not preclude the use of CBT to mitigate cognitive impairment in ME/CFS, but they do suggest that any effects of CBT may not be measurable by a single scale such as the SIP-ab.

A systematic review showed that while a few studies found improvement in symptoms over time, no variables, including gender or length of illness, predicted improvement or positive work or functional outcomes (Ross et al., 2002). Furthermore, analysis of existing studies revealed no evidence of treatments effective at restoring the ability to work. Another systematic review found that the placebo response is lower in behavioral intervention studies than in medical intervention studies of patients with ME/CFS (Cho et al., 2005).

Consistent with the findings of the systematic review of Ross and colleagues (2002, 2004), studies reviewed by Taylor and Kielhofner (2005) provided no evidence regarding the efficacy of employment rehabilitation, such as CBT and/or graded exercise therapy. Variation in methodologies, outcome measures, subject selection criteria, and other factors precluded drawing conclusions about the efficacy of interventions designed to enable ME/CFS patients to return to work.

SUMMARY

ME/CFS clearly impairs patients' ability to function on a regular basis both cognitively and physically. This impairment often confines patients to their homes or beds and may severely restrict their ability to attend to their jobs or schoolwork, among other responsibilities and basic needs. Recovery is a highly variable and generally lengthy process with no standard course of treatment, and some patients' symptoms may persist indefinitely. Health care providers should be familiar with SSA's guidelines for evaluating disability and recognize that diagnosis alone is not sufficient for receiving a disability status.

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Footnotes

1

Personal communication; public comments submitted to the IOM Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome for meeting 3, 2014.

Copyright 2015 by the National Academy of Sciences. All rights reserved.
Bookshelf ID: NBK284900

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