According to a new report having a brother or sister with a cardiovascular disease poses a greater risk than having a parent with a history of the disease.

The long running Framingham Heart Study, was conducted by the National Heart, Lung, and Blood Institute (NHLBI), which is a part of the National Institutes of Health (NIH).

The study has revealed that middle-aged individuals have as much as a 45 percent risk of having a cardiovascular event, such as a heart attack, stroke, or peripheral artery disease, if a brother or sister has had such an event.

The researchers say that even when adjustments were made for the fact that siblings may have similar lifestyle-related risk factors and may be of similar ages, the risk associated with having a sibling with cardiovascular disease remained high.

As a rule doctors will determine the relative risk for cardiovascular disease by evaluating known risk factors such as family history of heart disease, age, high blood pressure, High cholesterol, overweight, smoking, physical inactivity, and diabetes.

While many experts have suspected in the past that having a parent or sibling with heart disease increases the risk, this study shows quite clearly that having a sibling with heart disease is a significant risk factor independent of other measures.

NHLBI Director Dr.Elizabeth G. Nabel, says the study illustrates that even people who are not at high risk, based on their own health status, should talk to their doctors about the history of heart disease in their families, among siblings as well as parents, and ask what they can do to prevent a heart attack or stroke.

In the study the researchers evaluated siblings from among 1188 men and 1287 women, all were participants in the Framingham Heart Study.

All were at least 30 years old at the time of a baseline examination, and were followed for eight years for the occurrence of a cardiovascular disease event.

The study’s lead author Joanne Murabito, MD, ScM, of Boston University, says they determined that the risk from a sibling with a cardiovascular disease event remained elevated even after taking into account age and other risk factors that may cluster within families.

She suggests that risk may be even higher than the risk related to having a parent with cardiovascular disease, and is significant even in persons with borderline elevated levels of total cholesterol, when doctors are often undecided about medication treatment.

Unlike other studies of family history, the Framingham Study is one of the first studies to take an independent, unbiased look at sibling risk.

The study evaluated independent data from families over 57 years.

Participants in this study were the adult children of the original participants who first enrolled in the 1940s and 1950s.

Dr. Murabito says the findings suggest that taking an accurate family history should be a crucial part of every physician’s method of assessing heart disease risk, and should go beyond a simple ‘yes’ or ‘no’ question about the presence of disease in the family.

Murabito believes patients should make an effort to collect medical history information from their siblings and parents and make sure to inform their siblings if they have a cardiovascular disease event such as a heart attack or stroke.

She also believes that the reasons behind the strong association of risk between siblings are environmental as well as genetic, and as well as sharing the same genetic makeup, siblings may share similar dietary habits and physical activity patterns established in their early years while living in the same household, which may continue on into adulthood when genetic factors begin to manifest.

Christopher O’Donnell, MD, MPH, associate director of NHLBI’s Framingham Heart Study and the study senior author says that while family history cannot be controlled, there are many things which can be done to control the risk for heart disease, such as keeping your blood pressure, cholesterol and blood sugar under control, maintaining a healthy weight, avoiding smoking, and getting regular physical activity.

The study appears in the December 28, 2005, edition of the Journal of the American Medical Association.

For more information about heart disease risk factors and the Framingham Heart Study, visit the NHLBI Web site at http://www.nhlbi.nih.gov