Depression appears to double the chance of dying in any given year for patients with coronary artery disease, according to a new study.
The researchers said such mental distress was a “stronger risk factor” than age, having had a heart attack, or diabetes.
The effect was seen if the person was depressed before or after diagnosis of the disease.
Nearly 25,000 people with coronary artery disease were tracked over an average of 10 years and about 15 per cent of them ended up being diagnosed with depression, according to a paper published in the .
Dr Heidi May, a cardiovascular epidemiologist at Intermountain Medical Centre Heart Institute in Salt Lake City, said: “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.
“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.
“We’ve completed several depression-related studies and been looking at this connection for many years.
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“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 wellbeing.”
Of more than 2,600 patients who became clinically depressed about 27 per cent did so within a year of being diagnosed with the disease. The figure was 37 per cent after five years.
And while depression seems to make the condition worse, being diagnosed is also a reason why some patients become depressed.
The reason why the chance of dying increased was not revealed by the study, but Dr May said it was possible patients were not following their treatment plans as closely as people in good mental health.
“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 behaviours.”
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She added that depression can also cause physiological changes to the body, which could also be a factor.
Dr May urged the medical community to take depression seriously when treating coronary artery disease.
“Patients who have depression need to be treated to improve not only their long-term risks but their quality of life,” she said.
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“I hope the takeaway is this: it doesn’t matter how long it’s been since the patient was diagnosed with coronary artery disease. Continued screening for depression needs to occur.
“After one year, it doesn’t mean they’re out of the woods. It should be ongoing, just like we keep measuring things like LDL cholesterol.”