Inside The Exam Room™ 11/07/2006
PERIPHERAL VASCULAR DISEASE RISK FACTORS
By Mark Ombrellaro, MD
Peripheral vascular disease (PVD) affects approximately 12% of the general population and 20% of those over age 70. Since atherosclerosis is a systemic disease process, one can consider peripheral vascular disease as being a marker for the presence of atherosclerosis in other vascular beds as well. Healthy patients without peripheral vascular disease typically will have annual mortality rates of 1.5% annually while those with peripheral vascular disease, approximately 5%. Risk factors for peripheral vascular disease include those for all atherosclerosis. Some of these factors are things which patients may have some control over while others they may not.
The risk for PVD increases 2X with each decade of life and shares equal prevalence between men and women. Non Caucasian race also appears to carry a 2X increased incidence of PVD. Smoking is associated with a 4-5X increase risk for development of PVD is among the single most important modifiable risk factor. It also acts to potentiate the effects of other risk factors, typically doubling the associated risk. While it seems intuitive that smoking cessation would be of great benefit to an individual by significantly lowering their risk of atherosclerotic vascular disease, the addictive nature of tobacco makes this a very difficult task. Getting someone to stop smoking on their own usually is ineffective. It is quite often that I have individuals come into the office and tell me that they have “quit smoking” or “quit several times” only to start up again months or years later. Structured educational programs developed around behavioral modification and physician advice tend to have 1 year abstinence rates of about 15-25%. Patients who continue to smoke may benefit from medications such as nicotine replacement or antidepressant therapies. Like any addiction, there is both the physical and the psychological effects of the addictive drug. In my practice, the patients who have been the most successful at stopping their cigarette use decide for themselves that they no longer wish to smoke, and then just stop. They want to give it up for either for themselves or their families, and that personal motivation is what allows them to move forward and not look back. Without trying to sound too much like a pessimist, individuals who are not psychologically motivated to quit, typically will not.
Diabetes is another significant risk factor for PVD. Patients with type 2 (adult onset) diabetes have a 4X increased risk over the general population, driven by hyperglycemia (increased blood sugar) and insulin resistance. Lifestyle improvements involving diet and exercise are really the primary strategies for treatment. Reducing calories in this circumstance is important in order to induce weight loss. We are all familiar with the multitude of weight loss strategies and the new diets and programs that continue to proliferate each year. In discussing weight and exercise strategies with patients, I am an advocate for keeping things very simple, and to start by focusing calories. Calories are quite simply, the fuel load for the body. The other thing you must consider is that the body will not allow you just to dump off excess fuel. Once you take it in, you have 2 outcomes: you use it, or you store it. So, if you take in more fuel than you use, that extra fuel is stored in the body as fat, and translates to weight gain. If you use more energy than you take in, that difference is taken from the previously stored fatty tissue. Weight gain (or weight loss) is a very simple equation: fuel in minus fuel used. Diet and exercise is a strategy of putting in less fuel and using more or what you already have. Concentrating on calories also makes you pay attention to portion size. It is quite eye opening to read food labels or cook books and see what portion sizes actually are.
Hyperlipidemia is another important atherosclerosis and peripheral vascular disease risk factor. For each 10 mg/dl increase in a person’s total cholesterol, risk increases 10%. Elevated low density lipoproteins (LDL or “bad cholesterol”) is typically associated with coronary artery disease, Low levels of high density lipoproteins (HDL or “good cholesterol”) or high levels of triglycerides tend to have a greater influence on peripheral vascular disease. Cholesterol can be modified somewhat through limiting one’s intake of high cholesterol content foods and saturated fats. Dietary manipulation may be able to reduce cholesterol by about 10% but the need for greater reduction typically requires drug therapy. Elevated homocysteine has also been described as a as a risk factor for cardiovascular and peripheral vascular diseases. Homocysteine promotes clot formation and also effects LDL cholesterol. What is nice is that it can be controlled with supplemental folic acid. Hypertension is another major risk factor associated with a 2X increased risk of PVD.