Critical Review Indicates Need for Standard Definition of Recovery in Studies of Chronic Fatigue Syndrome

Fred Friedberg, PhD

May 6, 2014 – In a critical review article, Associate Professor Fred Friedberg, PhD and colleagues pointed out the need for a standard definition of recovery in studies of chronic fatigue syndrome (CFS). Their review of the literature identified 22 articles published since 1988 that included an operational definition of recovery and reported recovery results. Each of the studies used a different definition of recovery and used different cutoff points to categorize a result as recovery. Not surprisingly, the outcomes varied widely, with reported recovery rates ranging from 0 to 66% in intervention studies and 2.6 to 62% in naturalistic studies.

Definitions of recovery used in the studies referred to one or more dimensions — return to pre-morbid function, measures of fatigue alone, function alone, both fatigue and function, or a brief global assessment. The variety of recovery concepts used in the literature and resulting uncertainties suggested a “need for recovery criteria that set high but reasonable standards for behavioral recovery that approach restoration of pre-morbid health.”

After ruling out measures of fatigue, successful adaptation to illness, return to pre-morbid function, and patient self-report as adequate definitions of recovery, the authors proposed the use of “broadly based assessments that include criteria for normalization of symptoms and functioning as well as patient perceptions that indicate a return to health,” coupled with an assessment of recovery time following physical and mental exertion. They concluded by recommending that in the absence of a clear consensus about the definition of recovery, investigators use the more appropriate and informative criterion of “clinically significant improvement.”

The article, titled “Defining recovery in chronic fatigue syndrome: a critical review,” was published in the May 2014 issue of Quality of Life Research. The lead author was Senior Research Analyst Jenna L. Adamowicz, MA. Indre Caikauskaite also contributed to the research.