Illness and disability in Danish Chronic Fatigue Syndrome patients at diagnosis and 5-year follow-up

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Abstract

Objective: Evaluation of the life impact of Chronic Fatigue Syndrome (CFS) over 5 years. Methods: Thirty-three adult patients meeting 1988 and 1994 CDC case criteria answered identical questionnaires at diagnosis and 5 years later, when a retrospective questionnaire was also completed. Results: Work disability was very high and increased further, social isolation remained high, emotional adjustment improved. There were increased problems with reading and with allergies. Two measures of improvement were used: The relation between these measures was weak. Length of illness, extent of disability and emotional adjustment were poorly related to measures of improvement. Average illness scores were unchanged, but most individuals improved in some ways while worsening or remaining the same in others. Only one participant (3%) neared recovery, one other was substantially better but still severely disabled. Conclusion: CFS patients exhibit severe, long-term functional impairment. Substantial improvement is uncommon, less than 6%. Allergies and aspects of cognition may worsen, emotional adjustment often improves.

Introduction

Studies of the natural course of Chronic Fatigue Syndrome (CFS) have produced inconsistent results, some showing significant proportions of patients improving or recovering, others contradicting these findings. Reasons cited for this variation include heterogeneity due to type of onset, differing types of sample (primary care, specialized clinic, population) and use of different case definitions. Three CFS case definitions have been in use over a period of 10–15 years: two CDC-defined definitions, Holmes et al. [1] and Fukuda et al. [2], and also a more lenient set of criteria, which does not require eight or more minor symptoms, Sharpe et al. [3]. The latter is often referred to as the “Oxford” definition. Other factors contributing to inconsistent results have been the lack of strict diagnostic work-up, problems with instruments, low response rates, reliance on overly simplified self-reports of improvement and the apparent heterogeneity of the illness itself. Another important reason for the inconsistency is that follow-up periods vary considerably.

Joyce et al. [4] performed a systematic review in 1997 of all studies of recovery from CFS. Length of follow-up varied from a few months to 3 years. In studies of subjects meeting operational CFS definitions, <10% returned to premorbid levels of functioning. In the remaining studies of patients in primary care, where less stringent criteria were used, at least 40% of patients improved. Hill et al. [5] followed severely ill patients for up to 4 years (average 3.4 years) and found that only 4% recovered. van der Werf et al. [6] found that complete recovery occurred only in patients with symptom duration of less than 15 month. Levine et al. [7] followed patients with epidemic neuromyasthenia for 10 years (New Zealand), and Strickland et al. [8] did a 10-year follow-up of an outbreak (Lake Tahoo) with very heterogeneous fatigue patients. Both studies found recovery rates of great variation depending on the measure used.

Tiersky et al. [9] studied neuropsychological functioning and employment status in CFS patients in a specialized clinic. The patients were reevaluated after a mean period of 3 years and 7 months following their initial visit. Results indicated that objective and subjective attention abilities, mood, level of fatigue and disability improve over time. However, overall, the prognosis for CFS appears to be poor, as the majority of participants remained functionally impaired over time and were unemployed at follow-up, despite the noted improvements.

Jason et al. [10] reviewed four studies on community-based subtypes of CFS. They found variations in sociodemographics, illness onset, illness duration, symptom frequency, comorbidity and stressful precipitating events affected outcome measures of fatigue, symptom severity, functional ability and psychiatric comorbidity.

DeBecker et al. [11] performed a definition-based analysis of symptoms in a large cohort of patients with CFS to assess the Holmes and Fukuda definitions compared with idiopathic chronic fatigue patients not meeting either CFS case definition. They found patients meeting the Holmes criteria had both more symptoms and the most severe symptoms. Jason et al. [12] compared the Fukuda definition with the “Oxford” and concluded that using the latter case definition probably produces more heterogeneous patients groups, including some patients with purely psychiatric disorders.

Hickie et al. [13] studied temporal stability of chronic fatigue patients in primary care over 1 year and found that chronic fatigue is a persistent diagnosis over time. Bell et al. [14] followed pediatric cases from his practice for up to 13 years and found 80% of patients with “satisfactory outcome,” but with mild to moderate persisting symptoms.

One conclusion supported by all studies is that CFS patients who fulfill strict diagnostic criteria [1], [2] have worse prognosis compared to patients fulfilling lenient criteria.

Functional impairment in CFS is well documented, starting in 1995 with Wessely [15]. Schweitzer et al. [16] studied the impact of CFS on social and family relationships, work and recreational activities. They found significantly impaired quality of life (QOL), especially in areas of social functioning. Anderson and Ferrans [17] found the overall scores on their QOL index to be significantly lower in CFS than in other chronic illness groups. Buchwald et al. [18] used the Short-Form General Health Survey (SF-36) in patients with CFS and chronic fatigue seen in a university-based referral clinic. Among the factors found to be associated with functional limitations, increasing fatigue appeared to have the greatest effect. Hardt et al. [19] studied profiles of impairments in patients from three different countries using the SF-36. Patients scored below normal on all subscales. They concluded that health-related QOL is poor in CFS patients from all three countries. All in all, these findings unambiguously suggest that QOL is particularly and uniquely disrupted in CFS.

The purpose of this study is to illustrate in more detail than previously the impact on patients' lives of severe CFS (meeting both Holmes and Fukuda case criteria). Daily activities, social isolation, cognitive difficulties and neuropsychological problems were studied over a 5-year period, using two kinds of self-report measure. Focusing on groups of patients functionally improved, worsened or remained unchanged over this period, we present a detailed and complex picture of the natural course of this illness over 5 years in a carefully diagnosed, culturally and ethnically homogeneous sample.

Section snippets

Data acquisition and scoring

In March of 1994 (Time One) a questionnaire was sent to the first 37 patients who had been diagnosed with CFS using the 1988 criteria [1] at the Department of Infectious Diseases, Rigshospitalet, Copenhagen. The same physician saw all patients. Work-up included physical history and examination, psychiatric examination and laboratory tests including blood cell count, immunoglobulins, C-reactive protein, electrolyte panel, renal, hepatic and thyroid function, and rheumatological and virological

Activities of daily life

In 1994, work disability was 77% (Table 1). Of the 35 patients, 25 had stopped working completely, 4 had various part-time works and only 6 patients had remained in previous jobs. In 1999, work disability had increased to 91%. One patient was in a part-time supported employment, two were part-time students and one was self-employed less than full time. None had full time or regular employment. Housework disability was 56% in 1994 and was almost unchanged in 1999.

Social impairment was high with

Discussion

This 5-year follow-up of patients meeting both 1988 [1] and 1994 [2] CFS case definitions suggests that (1) recovery and substantial improvement are uncommon; (2) social isolation is severe and changes little over time; (3) some cognitive functions may decline over time; (4) emotional adjustment tends to improve over time but is unrelated to illness improvement or reduced disability; (5) some nondefinitional symptoms, including reduced sexual function and increased allergy, may be common in

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    Conducted at the Department of Infectious Diseases, Rigshospitalet, Copenhagen.

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