Does somatic illness explain the association between common mental disorder and elevated mortality? Findings from extended follow-up of study members in the UK Health and Lifestyle Survey
- 1Department of Epidemiology and Public Health, University College London, London, UK
- 2MRC Centre for Cognitive Ageing & Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
- 3Medical Research Council Social & Public Health Sciences Unit, Glasgow, UK
- Correspondence to David Batty, Department of Epidemiology and Public Health, University College London, 1-19 Torrington Place, London WC1E 6BT, UK;
- Accepted 17 December 2011
- Published Online First 1 February 2012
Background Common mental disorder (psychological distress) is associated with an increased risk of disease-specific mortality. Given that physical illness is related to both exposure and outcome, it may explain this relation through confounding or mediation.
Methods The authors used a 20-year follow-up of the UK Health and Lifestyle Survey (6127 men and women) in which common mental disorder was ascertained at baseline using the 30 item General Health Questionnaire and physical illness using a range of enquiries. Study members were an average of 45.2 years (SD 17.0) at study induction.
Results In age-adjusted analyses, a 1 SD increase in common mental disorder score was associated with an elevated risk of mortality outcomes coronary heart disease (CHD) in men (HR 1.11, 95% CI 0.96 to 1.27), CHD in women (1.33, 1.16 to 1.51); plus, in men and women combined, stroke (1.13, 0.96 to 1.30), respiratory disease (1.31, 1.15 to 1.48), lung cancer (1.11, 0.92 to 1.33), ‘other’ cancer (1.14, 1.03 to 1.26) and all causes (1.18, 1.12 to 1.23). Controlling for prior physical illness effectively eliminated the common mental disorder–mortality relation in all analyses with the exception of CHD in women.
Conclusion That physical illness largely explains the link between common mental disorder and mortality in the present cohort is compatible with either a confounding or mediation explanation.
Funding The UK Health and Lifestyle Survey was funded by the Health Promotion Research Trust. GDB is a Wellcome Trust Career Development Fellow. MH is supported by the British Heart Foundation. The Medical Research Council (MRC) Social and Public Health Sciences Unit receives funding from the UK MRC and the Chief Scientist Office at the Scottish government Health Directorates. The Centre for Cognitive Ageing and Cognitive Epidemiology is supported by the Biotechnology and Biological Sciences Research Council, the Engineering and Physical Sciences Research Council, the Economic and Social Research Council, the Medical Research Council and the University of Edinburgh as part of the cross-council Lifelong Health and Well-being initiative.
Competing interests None.
Ethics approval Various LRECs UK-wide.
Provenance and peer review Not commissioned; externally peer reviewed.