Depression is a serious medical condition characterized by overwhelming feelings of sadness, despair, and discouragement. The National Institute of Mental Health estimates that almost 10% of American adults, or about 19 million people age 18 and older, experience some form of depression every year.

Research over the past two decades has shown that depression often accompanies other serious illnesses such as cardiovascular disease . The public health impact of depression and heart disease—separately as well as together—is enormous. Depression is a leading cause of disability worldwide, and cardiovascular disease is the leading cause of death in the United States.

Studies looking at the relationship between depression and coronary events have established that clinical depression is a risk factor for relapse following coronary artery bypass graft (CABG) surgery , which is a major operation to restore blood flow to an ailing heart muscle. However, these studies have had small sample sizes and short follow-up.

A new study, published in the August 23, 2003 issue of The Lancet , sought to assess whether depression is associated with an increased risk of mortality in a large sample of patients undergoing CABG surgery who were followed for several years. The researchers found that patients with moderate to severe depression were more than twice as likely to die than patients who were not depressed.

About the Study

The researchers assessed 817 patients undergoing CABG surgery at Duke University Medical Center between May 1989, and May 2001. Participants were mostly male (73%), mostly white (89%), and had a mean age of 61. They were excluded if they had serious medical co-morbidities like liver or renal disease, a history of stroke , or a psychiatric condition.

To evaluate for depression, participants completed the Center for Epidemiological Studies-Depression (CES-D) scale (a commonly used self-report measure of depression) the day before CABG surgery and again six months after CABG surgery. Researchers then followed the participants for up to 12 years.

The Findings

At baseline, before CABG surgery, 38% of patients had clinical depression (26% had mild depression and 12% had moderate to severe depression). Fifteen percent of patients died during follow-up.

The researchers found that after 12 years of follow-up, patients with moderate to severe depression at baseline were at significantly increased risk of death compared with those who were not depressed, even after adjusting for such factors as age, sex, smoking history, and previous myocardial infarction (heart attack). Patients with mild depression, however, had no excess risk compared with non-depressed patients.

In a separate analysis, the researchers showed that patients who were persistently depressed (depressed at baseline and at six months after surgery) had more than twice the risk of death than those who were never depressed. Patients who were depressed only at baseline (and not at six months), though, had no greater risk of death than those patients who were never depressed.

Although the association between CABG surgery and depression is compelling, there are limitations to the study. For example, participants in this study may not be representative of a typical post-CABG surgery population, especially since those with a previous history of depression and other serious medical conditions were excluded. In addition, because the researchers collected medical data only before the surgery, they were not able to assess how changes in health (regarding cardiac function and treatment for depression in particular) during the follow-up period could have affected symptoms of depression.

How Does This Affect You?

While depression may seem to be an understandable, even expected, reaction to CABG surgery, this study strongly suggests that it should not be taken lightly. Participants with moderate to severe depression had a more than two-fold risk of death following CABG surgery compared to patients who were not depressed. Future research will need to explore to what extent treatment for depression after surgery could reduce the risk of death.

In any case, if you know or suspect that you are depressed, talk with your health care provider—especially if you are in the throes of a major life stress like cardiac surgery.