Mortality Rate Doubles for Patients with Depression, Heart Disease

Developing depression after a diagnosis of coronary heart disease is a large predictor of death.

Patients who develop depression after being diagnosed with coronary artery disease may have twice the risk of mortality compared with patients without depression, according to a new study published by the European Heart Journal—Quality of Care & Clinical Outcomes.

The authors found that an increase in all-cause mortality was observed to be true, regardless of whether the onset of depression occurs immediately after heart disease diagnosis or years after.

"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 study author Heidi May, PhD. "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."

Included in the study were 24,138 patients who received an angiogram and were diagnosed with coronary artery disease. To determine depression, the authors consulted diagnostic codes. Patients were grouped based on when they were diagnosed with depression in respect to heart disease diagnosis.

The authors reported that a majority of research has looked at depression at a single point in time, rather than a span of years. The current study followed patients for an average of 10 years after their heart disease diagnosis.

Of all patients included, 15% developed depression, with 27% diagnosed within 1 year of their heart event. Another 24% of patients developed depression between 1 to 3 years after, according to the study. Additionally, 15% developed the condition 3 to 5 years after the event and 37% developed depression at least 5 years after the event.

Interestingly, depression after a diagnosis of coronary artery disease was the largest predictor of death, even after other factors were accounted for.

That association also did not change for patients who received a depression diagnosis prior to being diagnosed with heart disease, or for those whose angiograms were performed for various reasons, according to the study.

These findings support prior studies evaluating the association between depression, heart disease, and increased risk of mortality, the authors noted. It has been established that coronary artery disease may lead to premature death, according to the study.

Although life expectancy has increased with optimal treatment, depression has been thought to play a role in mortality among patients with coronary artery disease.

"We've completed several depression-related studies and been looking at this connection for many years," Dr May said. "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."

The authors hypothesize that depression may worsen outcomes in patients with heart disease and heart disease may increase the risk of depression, according to the study.

While the study did not explore the underlying reason for the higher risk of death, the authors believe that depression may affect treatment adherence.

"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," Dr May 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."

Additionally, patients with depression also experience physiological changes.

The authors stress that continual screening for these patients is crucial for preventing premature deaths, according to the study.

"Patients who have depression need to be treated for it to improve not only their long-term risks but their quality of life," Dr May 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. Continued screening for depression needs to occur. 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."