Natural course and predicting self-reported improvement in patients with chronic fatigue syndrome with a relatively short illness duration

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Abstract

Objective: To describe the course of fatigue in chronic fatigue syndrome (CFS) patients with a relatively short duration of complaints and to test which psychosocial factors predict spontaneous improvement 1 year later. Methods: Seventy-nine patients with a complaint duration of less than 2 years were tested at baseline and 78 of the same group at 1-year follow-up. During this time period, no systematic intervention took place. Self-reported improvement and fatigue severity were the main outcome measures. Results: Forty-six percent (95% confidence intervals, 95CI=35–58%) of the patients with a short illness duration reported to be improved. This was a significantly (χ2=20.3, P<.001) higher percentage compared to the 20% (95CI=15–26%) self-reported improvement in a previously published natural-course study among 246 CFS patients with a longer illness duration. Persistence of complaints after 1-year follow-up was associated with high baseline levels of experienced concentration problems, less strong psychosocial causal explanations for the complaints, and higher levels of the experienced lack of social support. Baseline fatigue severity predicted fatigue severity at follow-up. Conclusion: The results showed that CFS patients with a relatively short duration of complaints had a more favourable outcome compared to patients with a long illness duration. The data also indicated that complete recovery only occurred in patients with a complaint duration of less than 15 months. This finding has important implications, since it suggests that after such a time period spontaneous recovery hardly occurs.

Introduction

Chronic fatigue syndrome (CFS) is characterised by severe disabling fatigue of definite onset, lasting longer than 6 months, and for which no somatic cause can be found [1]. Follow-up studies in patients with CFS showed that only small proportions of these patients, varying between 0% and 8%, recovered spontaneously [2], [3], [4], [5], [6]. The means of the illness duration in these studies ranged between 3 to 9 years, while the follow-up periods varied between 1 and 3 years. These differences make direct comparisons between these studies difficult. Nevertheless, the reported number of patients becoming symptom-free indicated that prognosis in CFS is rather poor. Follow-up data of patients who suffered prolonged fatigue (>1 month) but did not fulfill the criteria of 6-month illness duration showed that approximately half of the patients reported full recovery of their symptoms at follow-up [7], [8]. These discrepancies between recovery rates in CFS patients and recovery rates in studies concerning patients suffering prolonged fatigue do suggest a reversed relation between complaint duration and spontaneous recovery of symptoms. Some prospective studies have indeed found that illness duration in CFS was a predictor of persistence of fatigue [2], [9]. Therefore, there is a need for investigating prognosis in CFS patients with a relatively short duration of complaints.

In a previous study of natural course in CFS patients with a median duration of complaints of 5 years, 20% of the CFS patients reported improvement (including 3% recovery) in complaints after a 112-year follow-up period [2]. In this study, the persistence of fatigue was not only predicted by long illness duration, high level of baseline fatigue, and functional disability, but also by the lack of perceived control over symptoms (low self-efficacy expectations) and strong physical attributions. The importance of physical attributions was confirmed by the cohort study of Wilson et al. [4], but illness duration, premorbid psychiatric diagnosis, and cell-mediated immune function, did not predict outcome. Another prospective study reported long illness duration and low internal locus of control to be significant predictors for persisting fatigue [9]. Based on their data, the authors suggested that interventions should enhance perceived control. Bombardier and Buchwald [3] surveyed large groups (>400) of persons with chronic fatigue and found that prognostic indicators differed for both groups. However, the presence of dysthymia at baseline predicted poorer outcome in both groups.

An uncontrolled intervention study found that CFS patients with a shorter illness duration had a lower incidence of psychiatric disorder [10]. The authors of this study also reported that the effectiveness of counselling was greater in patients with a relatively short illness duration. The average complaint duration in their sample was 21 months, and after counselling 80% of their patients reported improvement at follow-up.

In summary, most of the described studies suggested a possible relation between illness duration and spontaneous recovery, while psychosocial factors were consistently found to predict outcome. In spite of this, most of the data were limited to patients with a relatively long illness duration. Consequently, this follow-up study was aimed at assessing improvement rates in patients with a recent diagnosis of CFS (maximum illness duration of 2 years) and to compare them with the findings in our previous natural-course study. Furthermore, it was tested whether similar or other psychosocial factors as found in our previous natural-course study predicted outcome. Based on the literature, we expected higher improvement and recovery rates in patients with a relatively recent diagnosis of CFS.

Section snippets

Participants

This study was carried out at the University Medical Centre Nijmegen in the Netherlands and was approved by the Medical Ethical Committee. Informed consent was obtained prior to the start of the study. All patients with a major complaint of fatigue referred to the outpatient clinic of the Department of Internal Medicine were assessed by means of detailed history, physical examination, and computer assessment of questionnaires. Patients were eligible for the study if they met the U.S. Centers

Self-reported improvement

At follow-up, 6 (8%) patients indicated that they had no complaints anymore, 30 (38%) patients reported that they had less complaints, 29 patients reported that their complaints remained similar, and 13 (17%) patients indicated that their complaints had become worse. Thus, 46% (95CI=35–58%) of the patients reported to be improved or recovered, which was a significantly (χ2=21.2, P<.001) higher percentage compared to the 19% (95CI=13–25%) improvement in the comparison group of 199 patients with

Discussion

This study specifically targeted CFS patients with a relatively short illness duration. The findings suggested that a shorter illness duration was associated with higher rates of spontaneous improvement and recovery. Since no details were available concerning nonparticipants, there is some uncertainty whether the investigated sample might have been biased towards a more favourable illness course. Nevertheless, a post hoc analysis among equally fatigued and disabled patients of a previous

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