Illness perceptions and mood in chronic fatigue syndrome

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Abstract

Background: Individual beliefs and cognitions may affect adjustment to chronic fatigue syndrome (CFS) and illness perceptions, in particular, have been reported to correlate with both disability and psychological adjustment to CFS in self-diagnosed cases. Objectives: The aim of the present study was to examine these relationships in a clinic sample of CFS patients assessed by both a physician and psychiatrist. Method: A sample of 173 patients referred to a multidisciplinary CFS clinic and fulfilling current operational criteria for CFS [Ann Intern Med 121 (1994) 953; J R Soc Med 84 (1991) 118.] were randomly selected from the clinic database and surveyed with the Hospital Anxiety and Depression scale, Fatigue Questionnaire and Illness Perceptions Questionnaire [J Psychosom Res 37 (1993) 147; Psychol Health 11 (1996) 431; Acta Psychiatr Scand 67 (1983) 361.]. Results: A total of 126 patients responded (73% response rate). The illness perception components studied were consequences (of illness), illness identity, causes (of illness), the ability to control/cure the illness and (expected) timeline of the illness. These components accounted for 15%, 28% and 30% of the variance in levels of fatigue, depression and anxiety, respectively. Two of the illness perception components (consequences and illness identity) were stronger predictors of fatigue score than mood scores. Conclusions: These findings confirmed in a clinical sample that illness perceptions are associated with variation in both disability and psychological adjustment in CFS. Illness perceptions may have an important and long-lasting effect on adaptation to CFS, and it is necessary to have a greater understanding of their role in order to tailor effective interventions for the condition.

Introduction

The importance of illness representations and cognitions in adjustment to long term conditions, such as chronic fatigue syndrome (CFS) has been recently recognised [1]. Petrie et al. [2] have found that catastrophic thinking was related to increased disability and fatigue in CFS patients, even controlling for the number of symptoms, psychological disturbance and help-seeking behaviour. Ray et al. [3] found that aspects of illness beliefs could predict progression of CFS with a stronger belief in perceived controllability of the condition at initial assessment being linked to better outcome.

Mood may also have an effect on adjustment in CFS. Ray et al. [4] has found that emotional distress correlates with factors that are predictive of illness severity (i.e., cognitive difficulty). This suggests disturbed mood can indirectly affect CFS by exacerbating symptoms, thus, amplifying the severity of the individual's illness experience [5]. All these findings point to the concept of ‘illness perceptions’ [6], where individuals create a cognitive model of their illness, which may influence their adjustment to a chronic condition.

This cognitive model is supported in CFS by the study of Moss-Morris et al. [7] who found that illness perceptions were related to levels of disability and psychological adjustment. The generalisability of their findings is limited as the CFS sample that they studied was of self-diagnosed cases obtained through the Australian and New Zealand Myalgic Encephalomyelitis Society (ANZMES) — a national postal-based community service. The use of this sample poses several problems. The study relied on self-identified sufferers who may not have fulfilled CFS operational criteria [8]. Secondly, a further selection bias is that the ANZMES is a self-help organisation and one follow up study [9] found that members of self-help groups had greater functional impairment than nonmembers. Finally, as discussed by Sharpe et al. [9], patients who believe they have ‘M.E.’ may have different illness characteristics from those who consider themselves to be CFS sufferers — that is, greater disability, but less psychological distress.

For these reasons, it was felt important to reassess the role of illness perception in a less selected clinic sample of CFS patients, comprehensively assessed according to recent CDC criteria [8]. It was aimed to assess which illness perception components had greatest influence on disability (fatigue) and adjustment (mood), and to explore the relative importance of mood and illness perception components on fatigue.

Section snippets

Characteristics of clinic sample

The patients contacted for this study (n=173) had attended a CFS clinic in tertiary care. They were chosen randomly from a database of 355 consecutive referrals between June 1995 and February 1997 who all fulfilled both the Oxford criteria for CFS [10] and the 1994 CDC criteria for CFS [8]. All patients had a primary complaint of chronic disabling mental and physical fatigue and were firstly assessed by an infectious diseases physician (PS), then by a liaison psychiatrist (SL). Patients with

Initial analysis

At the time of the survey, 29.8% of the respondents were HAD depression ‘cases’ and 32.3% were anxiety ‘cases.’

The ‘illness identity’ component of the Illness Perception Questionnaire showed the principal causes to which illness onset was ascribed. Eighty-eight (69.6%) patients believed that a germ or virus was the trigger for CFS. Most respondents did not accept any ‘emotional’ explanation for the condition, with only 34 (27%) believing a cause may have been their ‘own behaviour,’ and only 29

Discussion

This study had a large, thoroughly assessed sample of clinically diagnosed CFS sufferers, and confirmed that illness perceptions can explain a significant percentage of variance in levels of emotional adjustment (depression and anxiety) and, to a lesser degree, levels of fatigue in CFS. Less than a third of the sample were HAD anxiety or depression cases, yet, the correlations found suggest that those who did have significant mood disturbances and higher fatigue levels also had more

Acknowledgements

We thank Drs. D. Hargreaves, S. Rashid and G. Hill, K. Suresh for the assessment of patients and are grateful to Dr. Peter Trigwell, Consultant Liaison Psychiatrist, Leeds General Infirmary, for his advice on the use of the Illness Perception Questionnaire. A grant from Leeds CMHS Trust Charitable Funds funded Rupalee Suresh, grants from Shire Pharmaceuticals and the Northern and Yorkshire NHS Executive R&D Directorate funded Rachel Edwards. Paul Clarkson was funded by Northern and Yorkshire

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