Cardiovascular disease, including stroke and heart disease, is the number-one cause of death in both the U.S. and Denmark. Researchers from Odense University Hospital and other Denmark hospitals wanted to see if screening a large number of men for undiagnosed cardiovascular disease—and treating those at risk—would significantly decrease their death rate over about five years. Their results were presented at the European Society of Cardiology meeting and published in The New England Journal of Medicine.
The Danish Cardiovascular Screening (DANCAVAS) trial follows another Danish screening trial for cardiovascular disease in older men called the Viborg Vascular trial. This trial screened men for abdominal aortic aneurism, peripheral artery disease and hypertension. Identifying and treating these conditions reduced the five-year death rate by a significant 7 percent.
Screening Men Who Are Symptom Free
Screening exams are diagnostic tests that look for early diseases that have not been diagnosed by signs or symptoms, called subclinical disease. The DANCAVAS trial included more than 45,000 Danish men ages 65 to 74. Some of these men received screening tests designed to detect subclinical cardiovascular disease. They were compared with men who did not receive screening.
The screening tests included blood testing for diabetes and high cholesterol and blood pressure measurements of the arm and ankle. The men also had an imaging study of the heart called a coronary calcium scan. This is a type of CT scan that measures the amount of calcium in the blood vessels that supply your heart. Since calcium forms in the plaques that cause coronary heart disease, a high calcium score means a high risk for a heart attack. Comparing the blood pressure in your arm to the blood pressure in your ankle is a way to measure peripheral artery disease, which is a risk factor for both heart attack and stroke.
Age Range Makes a Difference
For all the men in the study, there was very little difference in any cause of death between five and six years after screening. Unscreened men had a five-year death rate of 13.1 percent, and the screened men had a death rate of 12.6 percent. This difference was not enough to recommend screening. However, when only men ages 65 to 69 were compared, there was a significant benefit to screening. In this subgroup of the study, men who were screened had an 11 percent lower five-year death rate, which is very significant.
The researchers note that men with positive screening tests were treated with medications to lower cholesterol and reduce stroke risk, which probably accounts for their improved survival due to less heart attacks and strokes. They also suspect that this benefit was found only in the younger men because they were less likely to already be on cardiovascular disease prevention medication and they were more likely to still be smokers. Overall, more than 50 percent of men in the study were already on blood pressure medication, more than 30 precent on cholesterol medication and more than 25 percent on blood-thinning medication.
More research is needed, and the current study group has begun enrolling men ages 60 to 64 for the DANCAVAS II trial. Researchers still need to answer additional questions, such as will this type of screening work in other countries and will it work in women as well as men. Women were not included in this study because they have a lower overall rate of heart attack and stroke than men, making mixed comparisons less reliable. Before this type of screening can be used outside a clinical trial, questions of accessibility and affordability will also need to be addressed.