Depression–anxiety relationships with chronic physical conditions: Results from the World Mental Health surveys

Abstract

Background

Prior research on the association between affective disorders and physical conditions has been carried out in developed countries, usually in clinical populations, on a limited range of mental disorders and physical conditions, and has seldom taken into account the comorbidity between depressive and anxiety disorders.

Methods

Eighteen general population surveys were carried out among adults in 17 countries as part of the World Mental Health Surveys initiative (N = 42, 249). DSM-IV depressive and anxiety disorders were assessed using face-to-face interviews with the Composite International Diagnostic Interview (CIDI 3.0). Chronic physical conditions were ascertained via a standard checklist. The relationship between mental disorders and physical conditions was assessed by considering depressive and anxiety disorders independently (depression without anxiety; anxiety without depression) and conjointly (depression plus anxiety).

Results

All physical conditions were significantly associated with depressive and/or anxiety disorders but there was variation in the strength of association (ORs 1.2–4.5). Non-comorbid depressive and anxiety disorders were associated in equal degree with physical conditions. Comorbid depressive–anxiety disorder was more strongly associated with several physical conditions than were single mental disorders.

Limitations

Physical conditions were ascertained via self report, though for a number of conditions this was self-report of diagnosis by a physician.

Conclusions

Given the prevalence and clinical consequences of the co-occurrence of mental and physical disorders, attention to their comorbidity should remain a clinical and research priority.

Introduction

It is now well established that there is significant comorbidity (co-occurrence) of mental disorders, particularly mood disorders, with chronic physical conditions (Wells et al., 1989a, Wells et al., 1989b, Dew, 1998, Katon and Ciechanowski, 2002, Harter et al., 2003, McWilliams et al., 2003, Buist-Bouwman et al., 2005, Simon et al., 2006, Ortega et al., 2006). These associations have considerable individual and public health significance in their impact on role impairment (Sullivan et al., 1997, Kessler et al., 2003), treatment costs and adherence (Simon et al., 1995, Ciechanowski et al., 2000) and premature mortality risk (Harris and Barraclough, 1998, van Melle et al., 2004, Zhang et al., 2005). However, prior research on the strength of the association between mental disorders and physical conditions has been limited by a preponderance of clinical relative to general population studies, a restricted range of mental or physical conditions explored and an absence of information from developing countries.

There is a further limitation to the earlier research on this topic. Anxiety and depressive disorders often co-occur. Population surveys have found that about half those with a current mood disorder also have a comorbid anxiety disorder (Kessler et al., 1996, Scott et al., 2006). Since prior research has not usually taken this depression–anxiety comorbidity into account, it is not known whether the association of anxiety disorders with chronic physical conditions might be due to comorbid mood disorder, or conversely, whether the association of mood disorders with chronic physical conditions might be due to comorbid anxiety disorder. Additionally, comorbid depression–anxiety is believed to be a more severe and chronic form of psychological disorder than non-comorbid depressive or anxiety disorders (Angst, 1997), so it is of interest to determine if comorbid depressive–anxiety disorder is associated with increased risks of chronic physical conditions. Lastly, since prior research has typically studied single or small numbers of chronic physical conditions, it is not clear whether there are substantial differences in mental–physical comorbidity patterns across different chronic physical conditions.

This paper addresses these issues by using data from 18 surveys participating in the World Mental Health Surveys to investigate the association of 10 chronic physical conditions with depressive and anxiety disorders, taking the comorbidity between depressive and anxiety disorders into account. The objectives of this paper are: 1) to determine whether non-comorbid depressive disorder and/or non-comorbid anxiety disorder are associated with specific physical conditions; 2) to determine whether comorbid depressive–anxiety disorder is more strongly associated than is non-comorbid depressive or anxiety disorder with physical conditions; and 3) to contrast the strength of association of different chronic physical conditions with depressive and anxiety disorders.