A definition of recovery in myalgic encephalomyelitis and chronic fatigue syndrome should be based upon objective measures.

Abstract

INTRODUCTION: Adamowicz and colleagues recently proposed to use "a consistent definition of recovery that captures a broad-based return to health with  assessments of both fatigue and function as well as the patients' perceptions of  his/her recovery status" for patients with chronic fatigue syndrome (CFS).  METHODS: A qualitative analysis of case definitions for Myalgic encephalomyelitis  (ME) and CFS and methods to assess the symptoms and clinical status of ME and CFS  patients objectively. RESULTS: The criteria of CFS define a heterogeneous  disorder. ME, often used interchangeably with CFS, is principally defined by  muscle weakness, cognitive impairment etc., but above all post-exertional  "malaise": a long-lasting increase in symptoms, e.g. muscle pain and cognitive  deficits, after a minor exertion. The principle symptom of CFS however is  "chronic fatigue". Since post-exertional "malaise" is not obligatory for CFS,  only part of the CFS patients meet the diagnostic criteria for ME, while not all  ME patients qualify as CFS patients. There are several accepted methods to assess  characteristic symptoms and the clinical status of ME and CFS patients using  objective measures, e.g. (repeated) cardiopulmonary exercise tests. CONCLUSION:  To resolve the debate about the clinical status, proposed effectiveness of  therapies and recovery in ME and CFS, it is crucial to accurately diagnose  patients using well-defined criteria for ME and CFS and an objective assessment  of various typical symptoms, since subjective measures such as "fatigue" will  perpetuate the debate.