Dr Alan Goblea, Dr Marian Worcestera, Dr Peter Elliotta, Dr Barbara Murphya, Professor David Hareb, Professor Erika Froelicherc, Dr David Bartond
a Heart Research Centre
b The Austin Hospital
c University of California
d Monash University
beyondblue Victorian Centre of Excellence
Project completion year
Up to 20 per cent of people experience severe depression after acute myocardial infarction (AMI), and milder depressive symptoms are even more common. Despite the strong evidence of an association, a causal linkage between depression and AMI is less certain. Using comprehensive baseline data from a trial involving 224 men who had experienced an AMI during the early 1980s, the researchers investigated whether depression predicted cardiovascular disease (CVD) and all-cause mortality during the ensuing 24 years. Baseline data were collected in hospital, at three weeks, and at three, four and 12 months via interviews, self-report questionnaires, clinical assessment and treadmill tests. Admission medical characteristics were recorded in hospital. The Beck Depression Inventory (BDI) was completed by patients about three weeks after AMI and again at four and 12 months. Data analyses involved bivariate analyses, logistic regression analyses and Cox proportional hazards regression analyses.
One hundred and eighty-eight patients were alive three weeks after their AMI and completed depression screening; 27 were alive but did not complete screening (15 had inadequate English, four were withdrawn from the trial because of physical problems, four were non-compliant and four cases had administrative errors). At baseline, severe depression (BDI score ≥ 10) was present in 27 men (14.4 per cent); mild depressive symptoms (BDI scores 5–9) in 73 (38.8 per cent); and no depression (BDI score < 5) in 88 men (46.8 per cent).
Using multimodal tracking procedures, the mortality status of 220 of the 224 men (98.4 per cent) was determined. Of these, 158 (71.8 per cent) had died within 24 years of their AMI and most (111 participants, 70.3 per cent) died from CVD.
Analyses demonstrated that depression contributed to mortality at five and 10 years: even mild depressive symptoms were associated with mortality at the five-year mark. There was a trend towards an association between depression and 24 year death rates, but no significant correlation.
In effect, after controlling for severity of infarction and age, depression was not an independent predictor of mortality at 24 years. It was a contributing risk factor for early death, but the effect of depression on mortality lessened over time.
These findings differ from those of some previous investigators, who found significant depression in a greater proportion of patients early after AMI.
Implications for policy, practice and further research
The finding that depression remains an apparently independent risk factor for death for a number of years after an AMI has important implications for patient management. Depression is known to be associated with adverse outcomes, including non-adherence with advice and poorer quality of life. Early identification of patients with either major depression or milder depressive symptoms is therefore necessary, so that they can be appropriately managed.