Guiding Principles for the Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome The following document is based on input and feedback obtained from a panel of experts using a modified Delphi panel process. These experts were engaged by the Centre for Effective Practice on behalf of the Minis- try of Health and Long-Term Care.1 The following principles represent a suggested approach for the diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in primary care, based on available literature and expert opinion. This resource is intended to help primary care providers diagnose and treat patients with ME/CFS. The key features of ME/CFS are: Fatigue Post-Exertional Malaise • New/defined onset • Worsening of symptoms (e.g. soreness, feeling drained or sick) resulting from minimal physical, • Persistent mental, or cognitive exertion • Not resulting from other diagnoses, medical • Episodes of immobilizing post-exertional physical and/ problems, medications or mental fatigue and/or malaise • Accompanied by malaise and a range of other symptoms Consensus was achieved among the panel to support the use of the Canadian Consensus Definition for ME/ CFS2 or the Institute of Medicine 2015 Criteria for the Diagnosis of ME/CFS.3 Providers may consider using one, or both, of these resources in supporting their diagnosis, depending on their familiarity with ME/CFS.4 Providers may also consider the following in diagnosing patients using these definitions: • Orthostatic intolerance, as listed in the Institute of Medicine definition, may be present in patients but is not essential for a diagnosis of ME/CFS. Similarly, some symptoms listed in the Canadian Consensus Definition (i.e. autonomic, neuroendocrine, and immune manifestations) may be present in patients but will vary significantly from patient to patient. Providers should consider all of these symptoms and each patient’s history, clinical examination, and differential diagnoses and comorbidities that may aggravate ME/CFS in order to appropriately manage these symptoms. • The assessment of symptom severity may be conducted using the patient reported questions and scales outlined by the Institute of Medicine, by patient-reported severity, or by the criteria outline by the International Consensus Criteria.2,3 • Patients may also report: unrefreshing sleep, new sensitivities to food, medications, and/or chemicals; and/or reduced cognitive function (e.g. memory problems, difficulty concentrating/paying attention). Summer 2018 cep.health | @CEPHealth Guiding Principles for the Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Additional Notes and Resources • ME/CFS is a chronic condition that can cause significant lifestyle changes and functional impairment in affected patients. ME/CFS is often a comorbid condition – a diagnosis of ME/CFS is valid irrespective of other diagnoses and a diagnosis of ME/CFS does not exclude the presence of other conditions. • The diagnosis of ME/CFS will change as scientific research reveals new information about the symptoms, causes and treatments of this condition. Related Resources • Functional Capacity Scale5 • NASA Lean Test6 References 1 Ontario Ministry of Health and Long-Term Care. Time for Leadership: Recognizing and Improving Care, Task Force on Environmental Health - Phase 1 Report. 2017. Available from: http://www.health.gov.on.ca/en/common/ministry/publi- cations/reports/environmental_health_2017/default.aspx 2 Carruthers BM, Jain AK, De Meirleir KL, Peterson DL, Klimas NG, Lerner AM, et. al. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols. J Chron Fatigue Syn 2002: 11(1); 7-115. 3 Institute of Medicine of the National Academies. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Rede- fining an Illness. 2015. Available from: http://www.nationalacademies.org/hmd/Reports/2015/ME-CFS.aspx 4 Jason LA, Sunnquist M, Brown A, Newton JL, Strand EB, Vernon SD. Chronic fatigue syndrome versus systemic exertion intolerance disease. Fatigue: Biomed, Health & Behav 2015. 5 Bested A and Marshall L. Activity Log and Functional Capacity Scale. Available from: https://ocfp.on.ca/docs/commit- tee-documents/activity-log-and-functiona-capacity-scale.pdf?sfvrsn=3 6 Bateman Horne Centre. NASA 10 Minute Lean Test. Available from: https://batemanhornecenter.org/wp-content/up- loads/2016/09/NASA-Lean-Test-Instructions.pdf Summer 2018 cep.health | @CEPHealth.