Berkson's bias and the mood dimensions of bipolar disorder

Authors

  • E.J. Regeer,

    Corresponding author
    1. Altrecht Institute for Mental Health Care, Utrecht, The Netherlands
    • Altrecht GGZ, Lange Nieuwstraat 119, 3512 PG Utrecht, The Netherlands. Telephone (+31) 30 2308600, Fax (+31) 30 2308678
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  • L. Krabbendam,

    1. Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands
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  • R. De Graaf,

    1. Netherlands Institute of Mental Health and Addiction (Trimbos Institute), Utrecht, The Netherlands
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  • M. Ten Have,

    1. Netherlands Institute of Mental Health and Addiction (Trimbos Institute), Utrecht, The Netherlands
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  • W.A. Nolen,

    1. Department of Psychiatry, University Medical Center Groningen, Groningen, The Netherlands
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  • J. Van Os

    1. Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands
    2. Division of Psychological Medicine, Institute of Psychiatry, London, UK
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Abstract

In this paper we examined whether manic and depressive dimensions independently contribute to mental health service use and determined the degree of comorbidity between manic and depressive dimensions in individuals with and without mental health service use. If both depressive and manic episodes independently influence help-seeking behaviour, a higher level of comorbidity between these dimensions would be found in clinical as compared to non-clinical samples (i.e. Berkson's Bias). Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a prospective epidemiological survey in a representative sample of the Dutch population (N = 7076). Dimensions of depression and mania and mental health service use (MHSU) were assessed with the Composite International Diagnostic Interview (CIDI) at baseline, and prospectively one and three years later. Logistic regression was used to test whether depressive and manic dimensions both had independent effects on mental health service use. The degree of mania-comorbidity given the presence of depressive dimension was assessed as a function of MHSU, both retrospectively and prospectively. Manic and depressive dimensions contributed independently to mental health service use. Mania-comorbidity given the presence of depressive dimension was significantly higher in individuals with mental health service use than in those without, both retrospectively (16.7% versus 7.1%, p = 0.000) and prospectively (10.8% versus 6.6%, p = 0.017). We conclude that the bipolar phenotype consists of manic and depressive dimensions that may be much more loosely associated than (Berkson) biased clinical observations suggest. A dimension-specific approach may be more productive in clarifying the aetiology of mood dysregulation. Copyright © 2009 John Wiley & Sons, Ltd.

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