Depression and self-reported functional status: impact on mortality following acute myocardial infarction

Authors

  • Paul A. Kurdyak MD PhD,

    1. Scientist, Centre for Addiction and Mental Health, Toronto, Ontario, Canada and Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
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  • Alice Chong BSc,

    1. Analyst, Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
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  • William H. Gnam MD PhD,

    1. Scientist, Centre for Addiction and Mental Health, Toronto, Ontario, Canada and Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
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  • Paula Goering RN PhD,

    1. Scientist, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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  • David A. Alter MD PhD

    Corresponding author
    1. Scientist, Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, Clinical Epidemiology Unit of Sunnybrook Health Science Centre, Toronto, Ontario, Canada, Division of Cardiology and the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada and Department of Medicine, Department of Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
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Dr David Alter
Institute for Clinical Evaluative Sciences
G1 06, 2075 Bayview Avenue
Toronto, ON
Canada M4N 3M5
E-mail: david.alter@ices.on.ca

Abstract

Objective  The cause of increased post-AMI (acute myocardial infarction) mortality associated with depression remains poorly elucidated. The objective of this study was to examine the extent to which self-reported cardiac functional status accounted for depression–mortality associations following AMI.

Methods  Using a prospective cohort design (n = 1941), the authors obtained self-reported measures of depression and developed profiles of the patients' pre-hospitalization cardiac risks, co-morbid conditions and drugs and revascularization procedures during or following index AMI hospitalization. To create these profiles, the patients' self-reports were retrospectively linked to no less than 12 years' worth of previous hospitalization data. Mortality rates 2 years after acute MI were examined with and without sequential risk adjustment for age, sex, income, cardiovascular risk, co-morbid conditions, selected process-of-care factors and self-reported cardiac functional status.

Results  Depression was strongly correlated with 2-year mortality rate [crude hazard ratio (HR) of severe vs. minimal depression category, 2.48 (95% CI 1.20–5.15); P = 0.01]. However, after sequential adjustment for age, sex, income and self-reported cardiac functional status, the effect of depression was greatly attenuated [adjusted HR for severe vs. minimal depression category, 1.35 (95% CI 0.63–2.87); P = 0.44]. Cardiac risk factors and non-cardiac co-morbidities had negligible explanatory effect.

Discussion  The main factor determining the increased mortality rate in depressed patients is self-reported cardiac functional status. Efforts to address increased mortality in depressed patients with cardiovascular illnesses should focus on processes that impact cardiac functional status.

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