DETROIT – Poor cardiorespiratory fitness combined with other risk factors can increase the long-term risk of death by nearly 34%, according to a study involving nearly 70,000 patients of Henry Ford Hospital.
Researchers made the finding during the Henry Ford ExercIse Testing Project, or FIT Project, the largest study of cardiorespiratory fitness to date.
The unprecedented, long-term project looked at mortality rates of 69,858 patients age 18 to 96 who underwent treadmill stress testing between 1991 and 2009 at Henry Ford Health System facilities. This analysis included 58,818 patients who had no history of coronary blockages or heart failure.
Patients were referred by physicians for the treadmill testing, which measures how efficiently their heart transports blood and their body utilizes oxygen as they walk progressively faster and at steeper inclines.
Researchers then compared the patients’ cardiorespiratory fitness level to their risk factors for cardiovascular disease: age, sex, HDL cholesterol and cholesterol levels, race, systolic blood pressure, smoking, blood pressure medication use and diabetes. To estimate patients’ risk score, investigators used a new risk estimator calculator recommended by the American College of Cardiology and the American Heart Association in 2013.
“The people with the highest risk factor score and the lowest fitness level were associated with nearly a 34% increase in future relative risk for death compared to people who had the lowest risk score and the highest fitness level,” says Henry Ford Hospital researcher and study co-author Steven Keteyian, Ph.D.
The principal investigator of the FIT Project, Henry Ford attending cardiologist Mouaz H. Al-Mallah, M.D., who is also affiliated with King AbdulAziz Cardiac Center in Riyadh, Saudi Arabia, will present the findings March 16 at the American College of Cardiology’s 64th Annual Scientific Session and Expo in San Diego.
The FIT Project also shows that good cardiorespiratory fitness is associated with lower death rates regardless of how the person scores on the Risk Estimator, says Dr. Al-Mallah.
“The benefit of cardiorespiratory fitness is seen in all patients, regardless of where their level of risk begins,” says Dr. Al-Mallah. “Regardless of what your risk score tells you, you still have to be fit.”
Dr. Keteyian points out that regular exercise is the easiest way to improve cardiorespiratory fitness. Other factors that influence fitness are age and genetics.
Henry Ford researcher Clinton Brawner, PhD, and Michael Blaha, M.D., M.P.H., director of clinical research at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, are also involved in analyzing data from the FIT Project. Exercise physiologists and nurses entered the treadmill, medical history and medication data into the patients’ electronic medical record. The FIT Project’s analysis of data was approved by the Henry Ford Health System institutional review board.