Abstract: The present disclosure relates to a method for determining a risk factor indicative of predicted growth of an abdominal aortic aneurysm of a patient. The method comprises receiving a value representative of a size of the abdominal aortic artery; and a flow-mediated vasodilation or flow-mediated constriction value of an artery of the patient (hereinafter “FMD/C value”). The method also comprises determining a risk factor indicative of predicted growth by evaluating the received values with those in an aneurysm risk model. The aneurysm risk model relates to a risk value indicative of predicted growth of an abdominal aortic aneurysm for a given value representative of the size of an abdominal aortic artery and a given FMD/C value.