Depression in CAD Trumps All Other Risk Factors for Death

Patrice Wendling

August 03, 2017

MURRAY, UT — Depression and coronary artery disease are known to walk hand in hand, but a new study suggests that depression any time after a diagnosis of CAD is the strongest predictor of death[1].

Among 24,137 patients identified with significant CAD, a new depression diagnosis was associated with a twofold higher risk of all-cause death after multivariable adjustment, the investigators reported in the European Heart Journal Quality of Care and Clinical Outcomes.

"It was stronger than any follow-up events, stronger than diabetes, stronger than smoking, sex, prior diagnosis of high blood pressure or depression, and even whether they had a heart attack," lead author Dr Heidi T May (Intermountain Heart Institute, Murray, UT) told theheart.org | Medscape Cardiology. "I thought it would be a significant predictor, but I didn't anticipate it would be the strongest.

"I would think most people would find that amazing."

She said the results emphasize the need for continual depression screening among all CAD patients, but an accompanying editorial[2] notes that recommendations by the American Heart Association (AHA) for routine screening in patients with heart disease have been met with some opposition, in large part because of a lack of studies showing a survival benefit with depression treatment.

"Given the uncertainty of whether treating major depression reduces the associated risk for mortality, it might be fruitful to consider whether depressive episodes can be prevented. To do this, we first have to identify the key risk factors for incident depression in patients with CAD," Drs Robert M Carney and Kenneth Freedland (Washington University School of Medicine, St Louis, MO) write in the editorial.

The current study provides some clues in this regard. The investigators used ICD codes to identify 3646 patients (15%) who had a new depression diagnosis and found they were significantly younger than those without depression (64 vs 65 years), more often female (37% vs 24%), diabetic (40% vs 30%), previously diagnosed with depression (26% vs 5%), and less likely to present with MI (28% vs 36%).

Patients with a depression diagnosis were significantly more likely to die during follow-up (median 8.9 years) than those without depression (50% vs 38.2%, P<0.0001).

Depression at any time following CAD was a significant risk factor for all-cause mortality in univariate (hazard ratio [HR] 2.18, P<0.0001) and multivariate (HR 2.00, P<0.0001) analyses.

The association was also confirmed in subgroups and in a landmark analysis of a depression diagnosis occurring within 1 year of a CAD diagnosis (HR 1.63, P<0.0001), 1 to 3 years (HR 1.48, P=0.004), 3 to 5 years (HR 1.93, P<0.0001), and >5 years (HR 1.20, P<0.0001).

Interestingly, 27.1% of patients were diagnosed within 1 year of their baseline CAD diagnosis and 15% in years 3 to 5, but 36.6% were diagnosed after 5 years.

"I thought there would be a little bit of a hot zone early on, but we had more patients diagnosed after 5 years than before," May said. "Patients are never out of the woods, and you need to continue to screen no matter how long it's been since a CAD event."

Dr François Lespérance (University of Montreal, QC), a psychiatry professor who was not involved with the study, said the high rate of late depression diagnoses is a good sign but that routine screening by cardiologists may not be the answer to improve detection rates.

"A lot depends on the context in which treatment is done," he said. "Screening is just the first step, but most of the work is after that, so you need someone who is able to do this and has the resources."

He continued, "There's also more probability that proper treatment will be followed if someone knows the patient well and can relate to their concerns and knows when to refer to a psychologist or psychiatrist. So the best people for screening and management are primary-care physicians or nurses rather than cardiologists."

That said, Lespérance said it's important for cardiologists to understand the risks and stigma associated with depression and to be involved in patients' follow-up, particularly for complex CAD patients.

"What they can do is to give patients with depression the best medical treatment for their cardiovascular disease and make sure they take it. Because we know that depressed patients are less likely to comply with medications, less likely to exercise, and less likely to control their diet or diabetes," he said. "By treating the cardiovascular risk, we may decrease the symptoms of depression."

The study authors, editorialists, and Lespérance reported no relevant financial relationships.  

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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