Department of Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Expert Centre for Chronic Fatigue, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Department of Medical Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Department of Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
Correspondence: Dr Judith Prins, University Medical Centre Nijmegen, 118 Medical Psychology, PO Box 9101, 6500 HB Nijmegen, The Netherlands. E-mail: j.prins{at}mps.umcn.nl
Declaration of interest None. Funding detailed in Acknowledgement.
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ABSTRACT |
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INTRODUCTION |
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METHOD |
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For comparison we used the published data of a Dutch general population sample with the same age range, in which the same diagnostic categories of DSM-III-R mood and anxiety disorders were obtained using a similar clinical interview (the Composite International Diagnostic Interview; CIDI) during the same period (Bijl et al, 1998).
Statistical analysis
Lifetime prevalence refers to disorders at some time in a participant's
life and current prevalence refers to disorders at the time of the study.
Controlling for overlap between depression and CFS, mood disorders were
calculated both with and without fatigue and/or poor concentration. We used
Z-scores to compare percentages of psychiatric disorders in the trial
participants and in the general population. Percentages of participants with
and without psychiatric disorders in those completing and not completing the
trial were compared using Fisher's exact test. Main and interaction effects of
psychiatric diagnoses on the outcome variables were analysed with a general
linear model for repeated measurements, with trial condition, current
psychiatric diagnosis and their first-order interactions as independent
variables.
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RESULTS |
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Participants with lifetime or current psychiatric disorders were not significantly different from those without in terms of age, duration of complaints, education, fatigue and functional impairment. Gender differences were found in lifetime psychiatric diagnoses (female 53.9% v. male 36.2%, P <50.05), but not in current psychiatric disorders (33% v. 29%).
Compared with the general population, lifetime and current mood disorders in the trial participants were significantly higher (37.1% v. 19.1%; Z=7.2, P <0.0001; 18.9% v. 3.9%; Z=12.5, P <0.0001). No significant differences were found between lifetime and current anxiety disorders (19.7% v. 19.3%; Z=0.16, P=0.87; 13.3% v. 9.7%; Z=1.89, P=0.058). No significant differences were found between participants with and without lifetime or current psychiatric diagnoses in the groups of those who completed or did not complete the trial. After controlling for CFS symptoms, fatigue and poor concentration, we found lifetime and current mood disorders in 26.5 and 14% of participants respectively, and lifetime and current psychiatric disorders in 42.8 and 28.4% respectively.
Psychiatric disorders and treatment outcome
In the outcome variables fatigue severity and functional impairment,
neither main effects of current psychiatric diagnosis (F=0.333,
P=0.564; F=0.209, P=0.209) nor interaction effects
of trial condition and current psychiatric diagnosis (F=0.065,
P=0.937; F=0.848, P=0.430) were found. Participants
with a current psychiatric diagnosis had outcomes almost identical to those
without. In the outcome variables depression and psychological distress, main
effects of current psychiatric diagnosis (F=25.4, P
<0.001; F=20.2, P <0.001) were found but no
interaction effects of trial condition and psychiatric diagnosis
(F=0.067; P=0.935; F=0.306, P=0.737). This
indicated that participants with a current psychiatric diagnosis had higher
BDI and SCL-90 scores at baseline, 8 and 14 months, compared with patients
without a current psychiatric diagnosis, but both groups had similar
difference scores from baseline to post-test and follow-up.
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DISCUSSION |
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The question arises whether overdiagnosis explains the higher percentages of mood disorders in people with CFS than in the general population. Controlling for CFS symptoms, respectively 9 and 5% fewer mood disorders resulted. Since more CFS patients were female, a gender effect might also explain the differences.
In contrast to what we expected, equal treatment effects of CBT were found for participants with and without current psychiatric disorders. Depression and psychological distress also benefited from CBT specially tailored for CFS. Treating psychiatric comorbidity may relieve psychological distress, but does not alter fatigue severity. Another interesting finding concerned the natural course of CFS, which was not adversely affected by current psychiatric comorbidity over 14 months. This confirmed results of an earlier study, in which depression was not a significant factor in the persistence of CFS (Vercoulen et al, 1998).
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ACKNOWLEDGMENTS |
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REFERENCES |
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Beck, A. T., Steer, R. A. & Garbin, M. G. (1988) Psychometric properties of the Beck Depression Inventory. Twenty-five years of evaluation. Clinical Psychology Review, 8, 77 -100.[CrossRef]
Bergner, M., Bobbitt, R. A., Kressel, S., et al (1976) The sickness impact profile: conceptual formulation and methodology for the development of a health status measure. International Journal of Health Services, 6, 393-415.[Medline]
Beurskens, A. J. H. M., Bültmann, U., Kant, I. J., et
al (2000) Fatigue amongst working people: validity of a
questionnaire measure. Occupational and Environmental
Medicine, 57, 353
-357.
Bijl, R. V., Ravelli, A. & van Zessen, G. (1998) Prevalence of psychiatric disorder in the general population: results of the Netherlands Mental Health Survey and Incidence Study (NEMESIS). Social Psychiatry and Psychiatric Epidemiology, 33, 587 -595.[CrossRef][Medline]
Bonner, D., Ron, M., Chalder, T., et al (1994) Chronic fatigue syndrome: a follow-up study. Journal of Neurology, Neurosurgery and Psychiatry, 57, 617 -621.[Abstract]
Deale, A., Chalder, T., Marks, I., et al (1997) Cognitive behaviour therapy for chronic fatigue syndrome: a randomized controlled trial. American Journal of Psychiatry, 154, 408 -414.[Abstract]
Prins, J. B., Bleijenberg, G., Bazelmans, E., et al (2001) Cognitive behaviour therapy for chronic fatigue syndrome: a multicentre randomised controlled trial. Lancet, 357, 841 -847.[CrossRef][Medline]
Sharpe, M., Hawton, K., Simkin, S., et al
(1996) Cognitive behaviour therapy for the chronic fatigue
syn-drome: a randomized controlled trial. BMJ,
312, 22-26.
Spitzer, R. L., Williams, J. B., Gibbon, M., et al (1990) Structured Clinical Interview for DSM-III-R - Patient Edition.Washington, DC: American Psychiatric Press.
Vercoulen, J. H. M. M., Swanink, C. M. A., Galama, J. M. D., et al (1998) The persistence of fatigue in chronic fatigue syndrome and multiple sclerosis: the development of a model. Journal of Psychosomatic Research, 45, 507 -517.[CrossRef][Medline]
Wessely, S., Hotopf, M. & Sharpe, M. (1998) Chronic Fatigue and its Syndromes. Oxford: Oxford University Press.
Whiting, P., Bagnall, A., Sowden, A. J., et al
(2001) Interventions for the treatment and management of
chronic fatigue syndrome. JAMA,
286, 1360
-1366.
Received for publication May 6, 2004. Revision received January 7, 2005. Accepted for publication January 18, 2005.