People with symptoms of clinical depression who undergo coronary artery bypass surgery (CABG) have long been known to be at a higher risk of death, hospital readmissions and cardiac events. But does depression also influence how well a person functions physically after CABG? A team of Emory University School of Medicine and Yale University School of Medicine researchers -- headed by Emory Heart Center scientist Susmita Mallik, MD -- has found that the answer is "yes."
In research available on-line at the American Heart Association's Circulation web site (http://circ.ahajournals.org/) this week and scheduled for publication in the January 24th print edition of that medical journal, the scientists conclude that higher levels of depressive symptoms at the time of CABG are a strong risk factor for lack of functional benefits six months after the surgery.
"The functional outcome we studied can be defined as health status perceived by the patient in areas of health identified to be of value to the patient. For example, a patient with low physical functioning would be very limited in performing all physical activities, including bathing or dressing, have problems with work or other daily activities as a result of physical health and have very severe and extremely limiting pain," explains Dr. Mallik. "A person with high physical function would perform all types of physical activities, including the most vigorous, without limitations due to health and would have no problems with work or other daily activities and no pain or limitations due to pain."
The research team interviewed 963 patients after the research subjects underwent CABG and interviewed them again six months after the procedure. The patients were assessed for depression and physical function using standardized testing. The scientists found that patients with the highest depression scores were younger, more often female, and had worse physical function and higher comorbidity than patients with lower scores of depression. Even after adjusting for factors such as severity of coronary artery disease, angina and medical history, symptoms of depression remained a significant independent predictor of lack of functional improvement after CABG. In fact, a high depression score was more likely to predict worse physical functioning after CABG than traditional measures of disease severity such as previous heart attack, heart failure on admission, and a history of diabetes.
"These findings demonstrate that depressive symptoms are at least as important as traditional measures of cardiac function in predicting health status outcomes of patients undergoing CABG," says Dr. Mallik. "Our study indicates that depressive symptoms represent a critical factor predicting outcome after CABG and emphasizes the substantial importance of detection and treatment of depression in patients after CABG in order to improve their health status and quality of life."
Emory Heart Center scientist Viola Vaccarino, MD, PhD, who was part of he research team, points out that additional recent research has confirmed that depression affects the outcome of patients with heart disease -- and she believes many physicians are becoming more aware that depression is related to cardiac prognosis in patients with acute coronary syndrome. "However, we think that there is still insufficient awareness about this issue in busy clinical settings," Dr. Vaccarino notes. "Our data, and that of other investigators, indicate that cardiac patients should be routinely screened for depression."
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