Screening and Diagnosis of Peripheral Vascular Disease

The term "peripheral vascular disease (PVD)" refers to atherosclerosis of the blood vessels in the arms and legs, the peripheral vasculature. The arteries of the legs are most commonly involved, and the condition is sometimes called "hardening of the arteries". PVD or PAD (Peripheral Artery Disease) is a common and significant complication occurring in patients with type 2 diabetes. PVD is more common in individuals with diabetes than in the general population, and the presence of diabetes increases the risk of PVD progression, lower extremity amputations, and death.[1,2] Patients with diabetes and PVD tend to experience longer hospital stays and utilize significantly more resources contributing to greater healthcare cost.[3] PVD occurs as a result of arterial narrowing or obstruction thereby restricting blood flow to the distal tissue. Symptoms of lower limb PVD range from intermittent claudication (cramping) to pain at rest and, in severe cases, gangrene in the extremity.[4] However, most patients with significant peripheral vascular disease are asymptomatic.[5] Asymptomatic PVD is thought to occur in approximately 12% to 18% of the general population.[6] Early screening and diagnosis of asymptomatic PVD can be easily achieved and can possibly reduce the risks of further cardiovascular complications.[7]

PVD Screening

Several risk factors for the development of PVD are known and are illustrated in Table 1. Due to the fact that PVD is more common in individuals with diabetes, hyperglycemia, in theory, may play an important role in the development of PVD.[1]

However, no prospective study has identified hyperglycemia as an independent risk factor for PVD in type 2 diabetes. A recent analysis of the UKPDS data determined that approximately 2.7% of patients with diabetes developed PVD 6 years after diagnosis. This analysis also showed increased age, increased A1C, increased systolic blood pressure, lower HDL cholesterol, previous history of cardiovascular disease, and smoking to be independent risk factors. The data analysis also indicated that a 1% increase in A1C was associated with a 28% increase in risk of incident PVD.[1]

Table 1. Risk factors for PVD[8]

Screening techniques

The ankle brachial pressure index, one available screening technique, can identify the presence of PVD in asymptomatic patients. The evaluation of this technique has revealed a sensitivity of 97% and a specificity of 100% for detecting angiographically defined stenosis.[9] In addition, the ankle brachial pressure index has the potential to predict subsequent cardiovascular events.[6] Screening for asymptomatic PVD should be implemented in patients with a high risk of developing coronary heart disease including patients with hypertension, diabetes mellitus, hyperlipidemia, and patients who are smokers. There are currently no published clinical trials evaluating the benefits of PVD screenings on reducing the cardiovascular morbidity and mortality in patients with asymptomatic disease.[7]

Peripheral arterial disease

Peripheral arterial disease (PAD) is a specific type of PVD resulting from atherosclerotic plaques which occlude vital arteries in the lower extremities. The most common form of PVD, PAD has been found to be not only a major risk factor for lower extremity amputations, but also for cardiovascular and cerebrovascular disease.[10] In the US, more than 12 million people are thought to be affected by PAD, and it is uncertain how many of these people have diabetes.[10] More than half of all patients with PAD are asymptomatic or do not experience typical symptoms, 30% experience claudication, and the remainder experience severe symptoms of disease.[11] Diabetes and smoking are the strongest risk factors for PAD. Table 2 lists the risk factors for PAD.

Table 2. Risk factors for PAD[10]

*Inverse relationship exists between alcohol consumption and PAD.

Over a 5-year time period, nearly 27% of patients with PAD go on to experience symptom progression resulting in lower limb amputations in approximately 4%. Over this same 5-year time period, patients with PAD have an increased chance of developing severe cardiovascular complications with 20% sustaining a nonfatal event and an overall 30% mortality rate.[12]

Screening for PAD

Initial screening and assessment of PAD in patients with diabetes should begin with a thorough medical history and physical examination to help identify those patients with PAD risk factors, symptoms of claudication, rest pain, and/or functional impairment (Table 3). Evaluations based solely on medical history and physical exam can often be nonspecific and not reasonably accurate. The ankle brachial pressure (ABI) index is a noninvasive measurement for detection and severity of PAD. The ABI is defined as the ratio of the systolic blood pressure in the ankle divided by the systolic blood pressure in the arm. Tools involved in the ABI are a hand-held 5-10 MHz Doppler probe and a blood pressure cuff. The ABI is measured by placing the patient in a supine position for 5 minutes. Systolic blood pressure is measured in both arms, and the higher value is used as the denominator of the ABI. Systolic blood pressure is then measured in the dorsalis pedis and posterior tibial arteries by placing the cuff just above the ankle. The higher value is the numerator of the ABI in each limb. ABI diagnostic criteria are also listed in Table 3. Due to the high estimated prevalence of PAD in patients with diabetes, screenings should be performed regularly for the patient population listed in Table 4.

Table 3. Screening/assessment tools[10]

Table 4. ADA's recommendations for ABI screening[10]

Diagnosis of PAD

Timely diagnosis of PAD is imperative to identify high-risk patients and to initiate therapy designed to alleviate further complications. High-risk patients are those who have a high likelihood of developing subsequent MIs or stroke. Early diagnois allows for the treatment of symptoms, which may improve functional disability and eliminate the necessity of limb amputations.[10] PAD is often more subtle in its presentation in patients with diabetes than in those without diabetes. PAD in diabetes adversely affects quality of life, contributing to long-term disability and functional impairment. Finally, there are significant healthcare and economic costs associated with disease manifestations, reduced productivity, and personal expenses.

Conclusions

Peripheral vascular disease and peripheral arterial disease are common complications experienced by patients with diabetes. The cause of this higher prevalence is unknown, but some of the effect can be related to differing levels of intermediate cardiovascular risk factors in patients with diabetes. Diabetes generally can be associated with higher levels of hypertension, cigarette smoking, triglycerides, cholesterol, and other blood lipids.[13] PVD has been shown to occur more frequently in patients with diabetes; thus, hyperglycemia may have a direct role in the development of PVD. Identification of hyperglycemia and other risk factors for PVD would permit detection of individuals at high risk and guide strategies for prevention, as few therapeutic options exist for PVD.[1]

References

1. Adler AI, et al. UKPDS 59: Hyperglycemia and other potentially modifiable risk factors for peripheral vascular disease in type 2 diabetes. Diabetes Care. 2002;25:894-899.
2. Bird CE, Criqui MH, Fronek A, Denenberg JO, Klauber MR, Langer RD. Quantitative and qualitative progression of peripheral arterial disease by noninvasive testing. Vasc Med. 1999;4:15-21.
3. Currie CJ, Morgan CL, Peters JR. The epidemiology and cost of inpatient care for peripheral vascular disease, infection, neuropathy, and ulceration in diabetes. Diabetes Care. 1998;21:42-48.
4. Creager MA, Dzau VJ. Vascular diseases of the extremities. In: Braunwald E, Isselbacher KJ, Petersdorf RG, Wilson JD, Martin JB, Fauci AS, eds. Harrison's Principles of Internal Medicine. 13th ed. New York, NY: McGraw-Hill; 1994:1135-1137.
5. Fowkes FG, Housley E, Cawood EH, Macintyre CC, Ruckley CV, Prescott RJ. Edinburgh Artery Study. Prevalence of asymptomatic and symptomatic peripheral arterial disease in the general population. Int J Epidemiol. 1991;20:384-392.
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7. Khunti K. Screening for asymptomatic peripheral vascular disease in primary care. Br J Cardiol. 2003;10:315-317.
8. Krajewski LP, Olin JW. Atherosclerosis of the aorta and lower extremity arteries. In: Young JR, Olin JW, Bartholomew JR, eds. Peripheral Vascular Diseases. 2nd edition. Philadelphia, Pa: Mosby;1996:208-233.
9. Ouriel K, McDonnell AE, Metz CE, Zarins CK. Critical evaluation of stress testing in the diagnosis of peripheral vascular disease. Surgery. 1982;91:686-693.
10. American Diabetes Association. Peripheral arterial disease in people with diabetes. Diabetes Care. 2003;26:3333-3341.
11. Hiatt WR. Medical treatment of peripheral arterial disease and claudication. N Engl J Med. 2001;344:1608-1621.
12. Weitz JI, Byrne J, Clagett GP, Farkough ME, Porter JM, Sackett DL, Strandmess DE. Diagnosis and treatment of chronic arterial insufficiency of the lower extremities: a critical review. Circulation. 1996;94:3026-3049.
13. MacGregor AS, Price JF, Hau CM, Lee AJ, Carson MN, Fowkes FGR. Role of systolic blood pressure and plasma triglycerides in diabetic peripheral arterial disease. The Edinburgh Artery Study. Diabetes Care. 1999;22:453-458.