Atherosclerotic Vascular Disease Conference: Writing Group II: risk factors.

Traditional Risk Factors and Vascular Risk Most data derived from large populations pertaining to risk factors for noncoronary AVD are found in studies primarily focusing on coronary heart disease (CHD), such as the Framingham Heart Study,1 the Atherosclerosis Risk in Communities Study (ARIC),2 the Honolulu Heart Study,3 and the Strong Heart Study.4 With rare exception, the evidence from these studies suggests that the risk factors for noncoronary AVD are generally similar and independent of the end organ (eg, brain, kidney, or skeletal muscle) subserved by a given arteriolar vascular bed. Thus, age, family history, elevated lipid levels, cigarette smoking, systolic and diastolic hypertension, and diabetes are the major risk factors for cerebrovascular, aortic, renal, and lower-extremity AVD. Within these classic risk factors for atherothrombotic vascular disease, several studies have suggested that cigarette smoking and diabetes are the strongest risk factors for AVD.5,6 There have also been observations that the most frequent form of dyslipidemia associated with AVD is the combination of elevated triglyceride levels and low HDL cholesterol.7,8 These latter changes in lipids are typically seen in patients with diabetes and are consistent with the high incidence of AVD among persons with diabetes. Across these studies there has been a paucity of data to precisely define ethnic/racial and gender differences that might contribute to variations in the prevalence and incidence of clinical events and mortality. Some variations in prevalence of lower-extremity vascular disease have been observed in relation to gender and ethnicity, however.9 Diabetes is a greater risk factor for peripheral artery disease among women than men and is associated with peroneal and tibial AVD. Cigarette smoking is associated with aortoiliac AVD and a distinct hypoplastic aortoiliac syndrome in young women who are heavy smokers. The prevalence of peripheral artery disease also seems to be greater among African-American and Hispanic populations.10 In the case of cerebrovascular disease, African-American men and women have less vascular calcium and Japanese Americans have more intracranial than extracranial vascular disease. Finally, smoking and being male are risk factors for abdominal aortic aneurysm. The use of risk factors to predict vascular disease events has several facets that deserve consideration. First, several types of risk can be estimated. Healthcare providers tend to focus on relative risk. Persons at higher relative risk of vascular disease often require more education and treatment than the other patients in a clinical practice, and to a physician, relative risk may translate into relatively more time spent with the patient or a stronger indication for intervention. On the other hand, absolute risk, the actual risk of an event over a specific period of time, may be more important and meaningful to the person being screened. Another important type of risk is the population attributable risk (PAR), a key measure for organizations that monitor costs and resources. This risk is derived from the relative risk and frequency of the attribute in the population at large. PAR estimates can be developed only from population-based investigations, not case-control studies. High PAR percent estimates lead to development of prevention programs and strategies to reduce prevalence of the condition and the vascular disease risks associated with it. Risk estimation with equations derived from populationbased studies is dynamic. The current approach to vascular disease risk estimation involves assessment of factors such as age, gender, blood pressure, cigarette smoking, cholesterol, HDL cholesterol, and presence of diabetes. Drawing from the experience of the Framingham Heart Study and similar