Reducing Heterogeneity in Chronic Fatigue Syndrome: A Comparison with Depression and Multiple Sclerosis

Abstract

Chronic fatigue syndrome (CFS) is a heterogeneous illness characterized by a high prevalence of psychiatric problems. We reasoned that we could reduce heterogeneity by excluding patients with psychiatric problems preceding CFS. We compared the functional status, mood, fatigue level, and psychiatric status of this more homogeneous group of CFS patients with the same parameters in patients with mild multiple sclerosis and in patients with major depression or dysthymia. Patients with CFS and those with multiple sclerosis were similar in terms of level of anger, severity of depression, level of anxiety, and frequency of current psychiatric diagnoses. Patients with CFS resembled depressed patients in having impaired vigor and experiencing substantial fatigue and confusion--problems constituting part of the case definition of CFS. The group with CFS was not psychologically vulnerable before the development of this condition and maintained adequate networks of social support despite disabling illness. Stratification to exclude patients with prior psychiatric disease and those with mild CFS allowed us to define a group of patients with CFS who more resembled patients with mild MS than patients with major depression or dysthymia and thus were more likely to have illness with an infectious or immunologic cause. Use of such a stratification strategy should prove important in testing of the viral/immunologic hypothesis of the etiology of CFS.

Hormonal Responses to Exercise in Chronic Fatigue Syndrome

“…To reduce heterogeneity and to assure that subjects were seriously ill at the time of study [19], the women met additional inclusion criteria: they rated the severity of their symptoms as substantial or worse over the last month, were sick for less than 6 years and had no major psychiatric diagnosis in the 5 years prior to illness onset [20,21]. Fifteen age-and education-matched, sedentary controls were recruited who were healthy but had no more than one regular exercise session a week and did not have jobs requiring substantial physical activity.…”

Single-Blind, Placebo Phase-in Trial of Two Escalating Doses of Selegiline in the Chronic Fatigue Syndrome

“…One explanation suggested for these results is that the study patients had a severe form of CSF which might be less responsive to treatment [20]. In fact, we used a protocol purposely designed to select more severely ill patients, because such a tactic appears to reduce patient pool heterogeneity [21]. Despite this explanation, the only way to eliminate the alternative interpretations of our results is by a double-blind placebo-controlled trial.…”

A Subgroup of Patients with Chronic Fatigue Syndrome May Have a Disorder of Arousal~!2009-11-19~!2010-02-23~!2010-04-21~!

“…Patients fulfilled the 1994 case definition for CFS [8] and thus had no medical explanation for their symptoms based on history, physical examination or lab tests. Patients were further characterized as having severe CFS or not using previously published criteria [9] as well as for the presence of co-existing fibromyalgia (FM) based on the American College of Rheumatology's 1990 criteria [10] to see if either illness severity or presence of FM impacted on results. Psychiatric diagnosis according to DSM-IV criteria was made using the computerized version of the Diagnostic Interview Schedule (DIS-IV) [11].…”