The effect of comorbid medical diagnoses on disturbed sleep in chronic fatigue syndrome

ABSTRACT

Background

Chronic fatigue syndrome [CFS] may occur alone or with fibromyalgia. This has led some to believe the two occur along a common illness spectrum. Evaluating whether this is the case is important as differences in burden or severity of CFS with fibromyalgia (FM) would suggest different underlying pathophysiological processes.

Objective

To determine if Insomnia Severity Index [ISI] scores differ between patients with CFS and those with CFS plus FM. In addition, we aim to determine if insomnia severity is impacted by other comorbid medically unexplained diagnoses.

Methods

247 patients with CFS completed the ISI and the Centers for Epidemiological Study – Depression. Patient groups were stratified on CFS severity and the presence of FM. A secondary analysis was conducted to evaluate insomnia severity related to the number of comorbid medically unexplained diagnoses including, FM, multiple chemical sensitivity and/or irritable bowel syndrome.

Results

When controlling for depressed mood, ISI did not differ significantly across patient groups defined by CFS severity and FM status. However, independent of mood, ISI was sensitive to multiple diagnoses showing a significant increasing trend from CFS alone to CFS plus one, two or three comorbid diagnoses.

Conclusion

Although CFS severity and FM status do not impact insomnia severity, increased illness burden as manifested by multiple medically unexplained diagnoses does appear to influence insomnia. In contrast to our earlier studies, this study did not find that a comorbid diagnosis of FM in patients with CFS is related to a worse outcome in the variable of interest.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported in part by funds received by BHN from the Centers for Disease Control and Prevention [grant #200-2012-53463]

Notes on contributors

Aaron J. Stegner

Aaron J. Stegner is an independent biostatistician based in Madison, WI, with a research background in pain andfatigue associated with medically unexplained illnesses. Michelle Blate is a nurse practitioner in the Pain and Fatigue Study Center at theIcahn School of Medicine at Mount Sinai. Benjamin H. Natelson is a clinician/researcher trained in neurology and behavioral medicineand the current director of the Pain and Fatigue Study Center at the Icahn School of Medicine at Mount Sinai.