comorbidity

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Introduction

Comorbidity, or the co-occurrence of two distinct medical conditions, is a common phrase in both physical and mental health. Whilst the term was originally conceived to describe medical phenomena, the term was adopted by psychiatry in the description of more than one clinical presentation occurring simultaneously. However, its use in psychiatry is not without controversy. 

What we know already

Large-scale prevalence data can seemingly tell us much about the high rate of comorbidity in mental health. Data from US National Comorbidity Survey, for example, suggested that, of those reporting mental health difficulties (across a 12-month prevalence), only 55% carried a single psychiatric diagnosis.

One important area of recent research concerns the rates of comorbidity of physical and mental health difficulties, particularly in the area of chronic health conditions. Mental Elf blogs have reported that people with schizophrenia are significantly more likely to die from heart disease and cancer; while the National Schizophrenia Audit calls for improved monitoring of physical health in people with schizophrenia. We know that depression and anxiety are more common when a person has a chronic health problem, and this comorbidity leads to poorer clinical and quality of life outcomes. This has led to an increase in interventions targeting the psychological consequences of chronic ill health.

Areas of uncertainty

The controversy in psychiatric comorbidity is the issues of mutual exclusivity. We are not able to conclude as to whether ‘comorbid’ psychiatric diagnoses are separate clinical entities, or multiple features of the same underlying cause. This has led to much criticism of the term ‘psychiatric comorbidity’.

Furthermore, certain diagnostic labels, such as personality disorders, attract particular scrutiny, due to their high levels of comorbidity with other mental health diagnoses. Similarly, people often meet the criteria for more than one personality disorder. This again creates uncertainty as to the precise nature of the condition, or conditions, being diagnosed.

What’s in the pipeline?

The recent publication of the Diagnostic and Statistic Manual (DSM)-5 seemingly retains the notion that multiple distinct clinical diagnoses exist, thus maintaining the argument for psychiatric comorbidity. Alternative conceptualisations have been suggested, along dimensional models, such as ‘anxious-misery’, ‘externalising’ and ‘fear-based’ dimensions. However, these were not adopted in the DSM-5.

As our understanding of mental health conditions continues to improve, so too hopefully will our understanding of comorbidity, and its relevance to psychological and psychiatric phenomena.

References

First, M. B. (2005). Mutually exclusive versus co-occurring diagnostic categories: the challenge of diagnostic comorbidity. Psychopathology, 38, 206-210. [Abstract]

Kessler, R. C., Chiu, W. T., Demler, O., & Walters, E. E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of general psychiatry, 62, 617-627. [Abstract]

Naylor, C., Parsonage, M., McDaid, D., Knapp, M., Fossey, M. and Galea, A. (2012) Long-term conditions and mental health: the cost of co-morbidities. The King’s Fund, London, UK. [Full text]

Acknowledgement

Written by: Patrick Kennedy-Williams
Reviewed by:
Last updated: Sep 2015
Review due: Sep 2016

Our comorbidity Blogs

Pharmacotherapy for smoking cessation in severe mental illness

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Andrew Jones reports on a recent systematic review and network meta-analysis of the efficacy and tolerability of pharmacotherapy for smoking cessation in severe mental illness, which finds a promising but low quality result for bupropion and varenicline.

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Searching for solutions: a new brief intervention for comorbid substance misuse in acute psychiatric inpatients

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Ian Hamilton presents the findings of a recent pilot randomised trial of a brief intervention for comorbid substance misuse in psychiatric inpatient settings.

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Mark Smith reviews a recent prospective cohort study, which considers the impact of comorbid personality problems on response to IAPT (Improving Access to Psychological Therapies) treatment for depression and anxiety.

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Is it bipolar disorder or borderline personality disorder?

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Murtada Alsaif considers the challenges facing psychiatrists in diagnosing bipolar disorder or borderline personality disorder. He reports on a recent qualitative study that explores the practical experience of psychiatrists and nurses and concludes that clinical diagnostic practice cannot reliably distinguish the two conditions.

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Will it hurt? Chronic pain and psychological functioning

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Kirsten Lawson examines a recent meta-analysis of psychological functioning in people living with chronic pain. She discovers that anxiety is more common than depression in people with chronic pain and that practitioners should prioritise psychological functioning when caring for patients suffering from chronic pain.

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Ian Hamilton reviews a recent long-term US study of integrated care for people with a dual diagnosis of substance use and schizophrenia, which concludes that recovery is possible, but it takes time.

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Emily Stapley reports on a new JAMA meta-analysis, which finds that mental illnesses such as depression and binge eating disorder are common among patients seeking and undergoing bariatric surgery.

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Smoking and chronic mental illness: what’s the best way to quit or cut down?

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Meg Fluharty considers the findings of a BMJ State of the Art review, which looks at the evidence for smoking cessation in people with chronic mental illness such as schizophrenia, unipolar depression, bipolar depression, anxiety disorders and PTSD.

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New NICE Guideline on social care support for older people with multiple long-term conditions

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Sarah Carr takes a look at a new NICE Guideline on person-centred, integrated social care support for older people with multiple long-term conditions.

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Collaboration, collaboration, collaboration

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Kirsten Lawson explores the benefits of working across professional and therapeutic boundaries, highlighted beautifully by the recent COINCIDE RCT of collaborative care for patients with depression comorbid with diabetes or cardiovascular disease.

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