ATLANTA The more overweight you are, the younger you will be when heart disease strikes, which will result in more years of illness and fewer years to live compared to leaner patients, a large, long-term study has shown.
While the connection between a person's weight and earlier onset of heart disease has long been made, Duke University Medical Center researchers have measured the extent of the relationship by looking at 12 years of detailed data on more than 9,000 heart patients. The findings were prepared for presentation at the American Heart Association's annual scientific sessions.
The researchers uncovered a direct relationship between the age and the weight of patients when they first came to Duke for symptoms of heart disease: the median age of normal weight patients was 64, overweight patients were 61 years old, while the most obese were 57.
A similar pattern is reflected at the end of life: normal-weight adults with heart disease had a life expectancy of 78, compared to 77 for overweight patients and 74 for the most obese patients.
Moreover, in this study, the heavier the patient, the more statistically likely that he or she had high blood pressure, diabetes, high blood levels of cholesterol and a family history of heart disease. These patients also had heart disease longer than normal-weight patients, and treating obese patients cost an additional $10,000 in the 12 years after their initial cardiac event, compared to normal-weight patients.
"It's a clear message," said Dr. Eric Eisenstein, an investigator at Duke's Clinical Research Institute. "Patients who weigh more than is healthy for them are coming into the hospital earlier because of heart disease, are living with that disease longer and dying slightly earlier than patients of normal weight.
"There have been a number of studies that show weight is a risk factor for developing heart disease, but this study is different because it looks at how weight affects the long-term prognosis for patients with known heart disease," Eisenstein added in an interview. "We found that obesity independently predicts a reduced life span for these patients after accounting for other risk factors."
To make these conclusions, the research team looked at the records and made annual contact with 9,407 patients who had come to Duke for a diagnostic catheterization between 1986 and 1997. This procedure uses a thin probe to look inside the heart and is used when symptoms of a heart problem first surface in a patient.
National Institutes of Health guidelines, based on body mass index (BMI), were used to describe the patients' weight. Within the group, 31 percent (2,951 patients) were normal weight (BMI of 18.5 to 25); 42 percent (3,950 patients) were overweight (BMI of 25 to 30); 18 percent (1,694 patients) were "obese-1" (BMI of 30 to 35); almost 6 percent (555 patients) were "obese-2" (BMI of 35 to 40); and almost 3 percent, or 257 patients, were considered "obese-3" (BMI of 40 or greater).
The obese patients tended to be younger and more often were women or minorities than the overweight or normal weight patients, Eisenstein said.
Surprisingly, heart disease that was detected in the obese patients was less severe than that found in normal or overweight patients, and their 30-day mortality was comparatively less, the researchers found. "But this all makes sense, because symptoms of heart disease were occurring earlier in the obese patients, and it was less advanced at the time of diagnosis," Eisenstein said.
"A similar phenomenon is seen in people who smoke. Their first cardiac event typically occurs when they are younger, compared to non-smokers."
That short-term survival advantage disappears as obese patients live with their heart disease and other disorders, such as hypertension and diabetes, that arise, he said. For example, among normal-weight heart disease patients, 50 percent had hypertension and 18% had diabetes, but almost 65 percent of obese-1 patients had hypertension and 34 percent had diabetes. Among obese-3 patients, 72 percent have hypertension and almost 50 percent had diabetes.
Survival is also compromised with increasing weight, Eisenstein said. The researchers found that heavier patients had more cardiac "events," such as a heart attack, as well as an increasing number of treatment procedures like angioplasty and bypass surgery during the subsequent 12 years of the study. The time they spent being "sick" with heart disease was more than 20 percent longer than normal-weight patients, he said. Finally, using actual data as well as predictive models, the researchers conclude that obesity at the time heart disease is initially diagnosed can shorten life expectancy by as much as four years: normal-weight patients can expect to live to age 78; overweight and obese-1 to age 77, obese-2 to age 76 and the life expectancy for obese-3 patients is 74.
The study was funded by Roche Global Pharmaco Economic Research of Palo Alto, Calif.
Note to editors: Dr. Eisenstein will participate in an American Heart Association press conference on obesity and heart disease to be held 8:15 a.m. Wednesday, Nov. 10, at the AHA's newsroom in the Georgia World Congress Center.