Functional status of persons with chronic fatigue syndrome in the Wichita, Kansas, population

Abstract

Background: Scant research has adequately addressed the impact of chronic fatigue syndrome on patients' daily activities and quality of life. Enumerating specific problems related to quality of life in chronic fatigue syndrome patients can help us to better understand and manage this illness. This study addresses issues of functional status in persons with chronic fatigue syndrome and other fatiguing illnesses in a population based sample, which can be generalized to all persons with chronic fatigue.

Methods: We conducted a random telephone survey in Wichita, Kansas to identify persons with chronic fatigue syndrome and other fatiguing illnesses. Respondents reporting severe fatigue of at least 1 month's duration and randomly selected non-fatigued respondents were asked to participate in a detailed telephone interview. Participants were asked about symptoms, medical and psychiatric illnesses, and about physical, social, and recreational functioning. Those meeting the 1994 chronic fatigue syndrome case definition, as determined on the basis of their telephone responses, were invited for clinical evaluation to confirm a diagnosis of chronic fatigue syndrome. For this analysis, we evaluated unemployment due to fatigue, number of hours per week spent on work, chores, and other activities (currently and prior to the onset of fatigue), and energy level.

Results: There was no difference between persons with chronic fatigue syndrome and persons with a chronic fatigue syndrome-like illness that could be explained by a medical or psychiatric condition for any of the outcomes we measured except for unemployment due to fatigue (15% vs. 40%, P <.01). Persons with chronic fatigue syndrome and other fatiguing illnesses had substantially less energy and spent less time on hobbies, schooling, or volunteer work than did non-fatigued controls (P <.01).

Conclusions: Persons with chronic fatigue syndrome are as impaired as persons whose fatigue could be explained by a medical or psychiatric condition, and they have less energy than non-fatigued controls.

Figure 1

Study population as classified into fatigued and non-fatigued groups. *all CFS-like respondents who did not report an exclusionary condition were invited to participate in a clinical evaluation; †3 participants had inconclusive psychiatric assessments and could not be classified; Fatigue = severe fatigue of ≥ 1 month. Exclusion = subject reported a medical or psychiatric condition that would exclude a diagnosis of CFS. Prolonged Fatigue = severe fatigue ≥ 1 month but < 6 months. Chronic fatigue = severe fatigue ≥ 6 months, but without sufficient symptoms or fatigue severity to meet the 1994 CFS research case definition1. CFS-like = appears to meet the CFS case definition [1].Insufficient Fatigue = no longer reported sufficient symptoms or fatigue severity when evaluated clinically. Explained Syndromic Fatigue = appears to meet the CFS case definition, except that an exclusionary condition was either reported or discovered upon clinical evaluation.

Figure 2

Median number of activity hours per week for fatigue groups. *significantly different (P < .05) from corresponding fatigue group with exclusionary conditions; CFS and CFS-like groups are compared with the Explained Syndromic Fatigue group. † significantly different (P < .05) across the fatigue groups without exclusionary conditions. Bars represent 25th to 75th percentile.

Figure 3

Changes from before onset of fatigue to time of interview in number of hours per week spent on activities by different fatigue groups. §Hours reported at time of interview were significantly different from hours prior to the onset of fatigue (P < .01). Bars represent 25th to 75th percentile.

Figure 4

Energy level of fatigue groups on a scale from 1 to 100, 1 being the worst one could feel and 100 being the best. groups are statistically similar; ‡ significantly different from the adjacent group (P < .01);Bars represent 25th to 75th percentile.

Figure 5

Percentage of subjects unemployed due to fatiguing illness *significantly different (P < .05) from corresponding fatigue group with exclusionary conditions, CFS and CFS-like are both compared with Explained Syndromic Fatigue. Bars represent 95% confidence intervals.