At any time after a diagnosis of coronary artery disease (CAD), a subsequent diagnosis of depression may be associated with as much as a 2-fold higher risk of death than in patients in whom depression is not diagnosed, according to results from a study recently published in the European Heart Journal – Quality of Care & Clinical Outcomes.
“No matter how long or how short it was, patients were found to have twice the risk of dying compared to those who didn’t have a follow-up diagnosis of depression,” said lead author Heidi May, PhD, cardiovascular epidemiologist, Intermountain Medical Center Heart Institute, Salt Lake City, UT. “Depression was the strongest risk factor for dying, compared to any other risk factors we evaluated. That included age, heart failure, diabetes, high blood pressure, kidney failure, or having a heart attack or stroke.”
Dr. May and colleagues assessed the possible association of all-cause mortality and a subsequent diagnosis of depression in 24,137 patients with angiographically validated CAD (stenosis ≥ 70%). Among these patients, 155 received a diagnosis of depression during follow-up.
Patients with depression were significantly younger than those without (64 vs 65 years), female (37% vs 24%), diabetic (40% vs 30%), and were more likely to have a previous diagnosis of depression (26% vs 5%), and less likely to present with myocardial infarction (MI; 28% vs 36%).
After a mean follow-up of 9.7 years, 40% of patients died, including 50% of those with depression, and 38% of those without (P < 0.0001). After adjustment, researchers found that the strongest predictor of death was post-CAD depression (HR: 2.00; P < 0.001), and this association persisted in subgroups of patients with no previous diagnosis of depression (HR: 2.00; P < 00001), and according to angiography indication (stable angina HR: 1.84, P < 0.001; unstable angina HR: 2.25, P < 0.0001; and MI HR: 2.09, P < 0.0001).
These results support those of previous studies, which have demonstrated an association between depression, heart disease, and an increased risk of death.
“We’ve completed several depression-related studies and been looking at this connection for many years,” said Dr. May. “The data just keeps building on itself, showing that if you have heart disease and depression and it’s not appropriately treated in a timely fashion, it’s not a good thing for your long-term well-being.”
But the results do nothing to explain why this elevated risk of death occurs, noted Dr. May. She added, however, that medication compliance may play a role.
“We know people with depression tend to be less compliant with medication on average and probably in general aren’t following healthier diets or exercise regimens,” she said. “They tend to do a poorer job of doing things that are prescribed than people without depression. That certainly doesn’t mean you’re depressed so you’re going to be less compliant, but in general, they tend to follow those behaviors.”
The bottom-line, said Dr. May, is that clinicians need to perform continued and frequent screening for depression in all patients with heart disease.
“Patients who have depression need to be treated for it to improve not only their long-term risks but their quality of life,” she said. “I hope the takeaway is this: it doesn’t matter how long it’s been since the patient was diagnosed with coronary artery disease. After 1 year, it doesn’t mean they’re out of the woods. It should be ongoing, just like we keep measuring things like LDL cholesterol,” she concluded.