Pharmacologic Risk Factor Treatment of Peripheral Arterial Disease is Lacking and Requires Vascular Surgeon Participation
Article Outline
The pharmacologic treatment of the cardiovascular comorbidities in patients with peripheral arterial disease (PAD) can have a profound effect on the outcomes of these patients. Guidelines for the treatment of hypertension, hyperlipidemia, diabetes, and tobacco use have been published by the American Heart Association and American College of Cardiology (AHA/ACC). Patients with PAD are often under-treated for these conditions. We sought to evaluate the adherence to these established guidelines in all new patients presenting with PAD to a vascular surgery clinic and delineate the opportunity for vascular surgeon involvement in these treatments. Consecutive new patients with symptomatic, objectively proven PAD (ankle-brachial index < 0.9) were evaluated in a vascular surgery clinic by a staff vascular surgeon. PAD risk factors, pre-visit medications, and prior cardiovascular interventions were recorded. Patients were stratified whether they were receiving appropriate preventive pharmacotherapy and whether they were meeting AHA/ACC goals. In patients without prior cardiovascular history, screening for these conditions was performed. One hundred sixty-seven new patients were evaluated over a 1-year period. Objectively diagnosed PAD included intermittent claudication in 115 (69%) and critical limb ischemia in 52 (31%) patients. Average age was 67.8 years, and 73 patients (44%) were current smokers. At initial evaluation, only 115 (69%) patients reported antiplatelet use. Patients with a recorded diagnosis of hypertension met clinical guidelines in 39 instances (71%). Eighteen patients (20%) with diabetes mellitus had poor glycemic control (Hgb-A1C > 7.0%). Seventeen (19%) of 88 patients with a history of hyperlipidemia were not adequately treated. Vascular surgeon medical interventions resulted in 31% of patients being started on antiplatelet therapy, 29% of hypertension therapies were modified, 19% of established lipid therapy was modified, and lipid therapy was initiated in 20%. A new diagnosis of hypertension was made in 10 cases (6%) and hyperlipidemia in 13 cases (7%). Despite clear guidelines for the medical community regarding cardiovascular prevention, a large percentage of patients with symptomatic PAD presenting to the vascular surgery clinic are not receiving appropriate therapy for their comorbidities or are not meeting the established goals. Vascular surgeons have an important role in promoting vascular health through the systemic prevention of ischemic events.
Lower extremity peripheral arterial disease (PAD) constitutes a coronary heart disease equivalent. Patients with PAD are at increased risk of fatal and nonfatal ischemic atherothrombotic events (myocardial infarction and stroke).1 Clear guidelines for the prevention of cardiovascular events in patients with symptomatic PAD have been proposed by the American Heart Association/American College of Cardiology (AHA/ACC).1
Traditionally, vascular surgeons have focused on the perioperative pharmacologic treatment of the patient with PAD. The long-term atherothrombosis prevention in the PAD patient has been relegated to the primary care physicians. Unfortunately, PAD is often under-recognized and its associated risk factors are suboptimally managed in the primary care setting.2
This study reviews our experience with the pharmacotherapy of cardiovascular risk factors in patients presenting to the vascular surgery clinic with PAD. Identification of preventive strategies, determination of adherence to established goals, as well as appropriate new therapy implemented by our vascular surgeons were determined.
Methods
Retrospective analysis of our prospective atherothrombosis prevention registry identified 167 consecutive new patients presenting with symptomatic, objectively proven PAD during a 1-year period in the vascular clinic at the Loma Linda Veterans Affairs Medical Center. PAD risk factors, prior cardiovascular interventions, and preventive therapies were recorded. Patients were stratified as to whether or not they were receiving cardiovascular risk reduction medications, and if so, whether they were at target goal for protection according to the AHA/ACC guidelines for management of patients with PAD (Table I). The main outcomes measured were whether patients were receiving appropriate therapy, meeting the goals for such therapy, and the frequency of need for initiation or change in such therapy by the vascular surgeon.
Table I. AHA/ACC guidelines on preventive therapy goals in patients with PAD
| Factor | Goal |
|---|---|
| Antiplatelet use | All PAD patients unless contraindicated |
| Hyperlidemia | LDL < 100 mg/dl |
| Hypertension | 130/90 mm Hg |
| 120/80 mm Hg (DM, CKD) | |
| DM | Hgb-A1C < 7% |
| Tobacco | Abstinence |
Patients without a prior diagnosis of hypertension, hyperlipidemia, or diabetes were screened with routine physical examination (blood pressure measurement) and blood tests (lipid panel, Hgb-A1C). The rate of identification of a new diagnosis of significant cardiovascular risks (hypertension, hyperlipidemia, diabetes) was recorded.
Clinical data were exported into a statistical software program (SPSS for Windows v.10) and evaluated using Student's t-test, chi-squared analysis, and univariate/multivariate logistic regression analysis. P-values less than 0.05 were considered to be statistically significant.
Results
One hundred sixty-seven new patients with objectively proven PAD (ankle-brachial index < 0.9) were evaluated in the vascular clinic over a 1-year period. The reason for referral was intermittent claudication in 115 cases (69%) and critical limb ischemia in 52 (31%). Patients were predominately males (96%) with a mean age of 78 (ages 64 to 90). Coronary artery disease was present in 36 cases (22%), cerebrovascular disease in 15 (9%), and both in 25 (15%). Prior carotid endarterectomy was observed in 5.5%, abdominal aortic aneurysm repair in 3.7%, major amputations in 3.7%, coronary revascularization in 25%, and lower extremity revascularization in 11%. A prior diagnosis of hypertension was recorded in 133 cases (81%), dyslipidemia in 110 (66%), and diabetes in 92 (55%) patients. Active tobacco use was present in 44% of the cohort. Patients presenting with critical limb ischemia had a greater incidence of diabetes than patients with claudication (P < 0.001).
Upon presentation to the vascular clinic, cardiovascular medication use included antiplatelets in 69%, beta-blockers in 42%, ACE-inhibitors in 55%, statin-class drugs in 80%, diuretics in 30%, and calcium-channel blockers in 27% (Table II). When analysis of established prevascular clinic risk factor reduction therapy was performed, 115 (69%) of the cohort was receiving antiplatelet class drugs, 88 (80%) out of 110 labeled dyslipidemic patients were receiving statins, and all 135 hypertensive and 92 diabetics were receiving medications.
Table II. Prevalence of risk factor treatment prior to vascular clinic
| Risk factor | Total patients | Prevascular clinic therapy | No therapy |
|---|---|---|---|
| Antiplatelets | (167) | 115 (69%) | 52 (31%) |
| Hypertension | (135) | 135 (100%) | 0 (0 %) |
| Hyperlipidemia | (110) | 88 (80%) | 22 (20%) |
| Diabetes | (92) | 92 (100%) | 0 (0%) |
Aside from being on appropriate medication, analysis was performed to determine whether patients were achieving the goals set by the AHA/ACC guidelines (Table III). All patients with PAD should be on antiplatelet therapy; therefore 52 patients (31%) were not meeting the goal for antiplatelet use. Of the 110 patients with hyperlipidemia, 17 (19%) were not at goal for target low density lipoprotein. Of the 135 hypertensive patients, 39 (29%) were not at goal for hypertension. Eighteen patients (20%) with diabetes had elevated Hgb-A1C. The goal of abstinence from tobacco use was missed by the 73 patients (44%) with active tobacco use.
Table III. Patients achieving AHA target goal for risk factor
| Risk factor | Goal | No Goal |
|---|---|---|
| Antiplatelets (167) | 115 | 52 (31%) |
| Hypertension (135) | 96 | 39 (29%) |
| Lipids (88) | 71 | 17 (19%) |
| Diabetes (92) | 74 | 18 (20%) |
Intermittent claudication was associated with increased use of antiplatelet therapy (P < 0.05). There was no difference in the use of other cardioprotective medications when controlling for the presence of coronary artery disease, cerebrovascular disease, or the severity of PAD. No patient variables were found to correlate with attaining AHA/ACC target guidelines.
The vascular clinic initiated antiplatelet therapy in all 52 patients with PAD not previously receiving these medications. The medical therapy for hypertension was modified in 29% of patients with established hypertension who were not reaching the AHA target goal. A statin class drug was started in 20% of patients with a prior history of hyperlipidemia, and 19% of established current lipid regimens were modified based on continued elevated lipid levels. The 20% of patients with diabetes and elevated Hgb-A1C were referred to a diabetic specialist for further education and follow-up. All these changes were initiated for long-term cardiovascular risk reduction and not for perioperative cardiac protection.
A new diagnosis of hypertension was made in the vascular clinic in 10 of the 167 new patients (6%). Similarly, a new diagnosis of dyslipidemia was made in 13 of the new patients (8%). All newly diagnosed patients were started on appropriate medical therapy as established by AHA/ACC guidelines.
All 73 patients with active tobacco use were counseled during the clinic visit and referred to a comprehensive smoking cessation program offered in our institution.
Discussion
There is extensive documentation of increased cardiovascular morbidity and mortality in patients with atherosclerotic PAD.3, 4, 5, 6 Traditionally, training for the diagnosis and treatment of PAD has been on the shoulders of vascular surgeons. Vascular surgical referral is usually from primary care providers. Multiple publications support the lack of awareness of PAD diagnosis, less intensive treatment of risk factors, and under-prescription of antiplatelets when compared to other forms of atherosclerotic syndromes (coronary artery disease, cerebrovascular disease).2, 7 Recently the AHA/ACC in collaboration with the Society of Vascular Surgery and other societies' published guidelines for the management of lower extremity PAD.1 Evidence-based recommendations have been made specifically addressing prevention strategies in this morbid subset of patients.8, 9, 10, 11
In our study of newly referred symptomatic PAD patients, we have found the adherence to the AHA/ACC guidelines was less than desirable. This is consistent with other publications.12 Factors that contribute to pre-vascular clinic suboptimal management could be related to the referral physician or possibly the patient. Deficiencies in physician knowledge and attitudes contribute to a lower rate of atherosclerotic risk factor reduction in patients with PAD.13 Our study supports this finding as demonstrated by the lack of achieving goal therapy in the treatment of hyperlipidemia, hypertension, and diabetes in a large percentage of patients. We also noted that the only predictor of use of antiplatelet therapy was intermittent claudication, which underscores the lack of knowledge about the systemic disease process in patients with critical limb ischemia.13 A national detection and education program for PAD patients may address the pre-vascular clinic issue.
Another potential explanation, which has not been directly explored in the literature, is the education and compliance rate of the patients. Patients may not always follow the recommendations of the primary physician and often do not perceive the systemic nature of PAD. This factor could not be directly assessed in this current study. However, the nature of the Veterans Affairs electronic patient records allows us to safely state that the data on prescriptions likely over-estimate the actual treatment of these patients.
Although there are many possible explanations as to why these patients are under-treated before presenting to the vascular clinic, the surgeons should not be excused from accountability.14, 15 There are clear data that vascular surgeons believe in risk factor optimization, however controversy exists on how this process should be accomplished.16 An integrated health care system with electronic medical records and communication could represent a viable model of comprehensive care whereby vascular surgeons could initiate changes and interactively communicate to primary physicians and pharmacists17 for follow-up. Vascular surgeons who do not directly participate could be lacking core knowledge in implementing pharmacologic long-term atherothrombosis prevention, timely accessibility to laboratory values, or appropriate time during clinical visits. Vascular surgeons may also not wish to interfere with the primary care doctor and adversely affect their referral patterns. We acknowledge these challenges, however, all vascular practices should incorporate some method of aggressive risk factor assessment and modification to ensure complete vascular care. The utilization of physician extenders to follow laboratory screening tests, or the incorporation of a pharmacist into the management of these patients, may prove successful.17
Conclusions
A large percentage of patients with symptomatic lower extremity PAD presenting to the vascular clinic are not receiving appropriate cardiovascular pharmacotherapy or are not meeting their evidence-based protective goals. Methods to improve adherence to guidelines for risk factor management in PAD patients in the primary care setting must be explored. Vascular surgeons should take the lead in the care of these patients. Efforts to educate physicians and increase patient awareness may result in improvements at the primary care level prior to presentation to the vascular clinic. Vascular surgeons are likely to identify a significant number of preventive deficiencies in PAD patients and thereby contribute to improved outcome by influencing long-term patient care and educating the referral physicians. If vascular surgeons choose to manage risk factors, a high number of medical interventions will be necessary to promote vascular health. Formal education regarding risk reduction should be a core element of the modern vascular surgical training paradigm.
References
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- . Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ. 2002;324:71–86
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- MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomized placebo-controlled trial. Lancet. 2002;360:7–22
- . Meeting AHA/ACC secondary prevention goals in a vascular surgery practice: an opportunity we cannot afford to miss. J Vasc Surg. 2006;43:781–787
- . The lack of cardiovascular protection risk factor management in patients with critical limb ischemia. Eur J Vasc Endovasc Surg. 2001;21143–21146
- Atherosclerotic risk factor reduction in peripheral arterial disease. Results of a national physician survey. J Gen Intern Med. 2002;17:895–904
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- Su H, Gordon M, Roake J, Lewis D. Management of risk factors: a survey of New Zealand vascular surgeons. NZ Med J 2006 Mar 31;119:12-31.
- Effect of a clinical pharmacy service on lipid control in patients with peripheral arterial disease. J Vasc Surg. 2006;43:1205–1210
Presented at the 24th Annual Meeting of the Southern California Vascular Society, Temecula, CA, May 5-7, 2006.
PII: S0890-5096(07)00110-0
doi:10.1016/j.avsg.2007.01.008
© 2007 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
