Overview
To determine the mechanisms of association between depression and coronary heart disease (CHD), we performed a prospective cohort study of 1024 subjects with known CHD who were recruited between 9/00 and 12/02 and followed for 10 years. At the baseline examination, participants completed a structured diagnostic interview for depression, extensive questionnaire, EKG, 6-minute walk test, and exercise treadmill with stress echocardiography. Participants were instructed to bring their medication bottles to the study appointment, and study personnel recorded all current medications. Participants also completed 24-hour ambulatory Holter monitoring to determine heart rate variability and collected 24-hour urine for measurement of creatinine, free cortisol, and catecholamines. Fasting blood was drawn, and samples of serum, plasma, DNA, and 24-hour urine remain stored at –80 degrees Celsius. After 5 years of follow-up, 667 participants (>80% of survivors) completed a repeat examination that included a structured diagnostic interview for depression, questionnaire, EKG, exercise treadmill test, fasting blood draw and 24-hour urine. All participants were contacted annually to inquire about cardiovascular events, which were confirmed by review of medical records. At least 10 years of cardiovascular event outcomes were adjudicated for 93% of study participants, and mortality data will be collected indefinitely.
Inclusion criteria
We used administrative databases to identify outpatients with documented coronary artery disease at two Department of Veterans Affairs Medical Centers (San Francisco VA Medical Center and the VA Palo Alto Health Care System, California), one University medical center (University of California, San Francisco), and nine public health clinics in the Community Health Network of San Francisco. Patients were eligible to participate if they had known CHD documented by at least one of the following: a history of myocardial infarction, angiographic evidence of at least 50% stenosis in one or more coronary vessels, prior evidence of inducible ischemia by treadmill or nuclear testing, or a history of coronary revascularization.
Exclusion criteria
A total of 15,438 patients with CHD were identified from administrative databases and mailed an invitation to participate. Of the 2495 patients who returned a form indicating that they would be interested in participating, 505 could not be reached by telephone, and 370 were excluded because they had a history of myocardial infarction in the prior 6 months (treadmill test contra-indicated), deemed themselves unable to walk one block (treadmill test not useful), or were planning to move out of the local area within two years (unavailable for follow-up). Of the 1620 patients who were confirmed eligible, 596 declined to participate, and 1024 (63%) enrolled.
Participant characteristics
Between September 2000 and December 2002, a total of 1024 participants enrolled, including 385 from the San Francisco VA Medical Center, 55 from the VA Palo Alto Health Care System, 344 from the University of California, San Francisco, and 240 from the Community Health Network of San Francisco. Of the 1024 participants, 181 (18%) were women. There were 549 (54%) with a history of myocardial infarction, 237 (23%) with a history of revascularization but not myocardial infarction, and 238 (23%) with a diagnosis of coronary disease that was documented by their physician based on a positive angiogram or treadmill test. Participants were 60% non-Hispanic white, 9% Hispanic white, 17% African American, 11% Asian, and 3% other. The mean age was 67 (range 45-90) years at baseline.