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ABI and Limb Revascularization or Amputation in PAD
Study Questions:
Is the ankle-brachial index (ABI) associated with limb outcomes in community-dwelling patients with peripheral artery disease (PAD)?
Methods:
The authors evaluated a population-based, observational cohort of community-dwelling patients between 1998 and 2014 with PAD in Olmsted County, MN. ABI results, limb events, and medical therapies were identified through a computer algorithm within the electronic medical record. PAD was defined as an ABI of ≤0.9; severe PAD defined as an ABI ≤0.5; and poorly compressible vessels defined as ABI ≥1.4. Guideline-recommended therapies included statins, antiplatelet agents, angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs), and smoking abstention. Risk of revascularization and amputation was assessed after adjusting for age, sex, and the presence of critical limb ischemia.
Results:
Of the 1,413 patients with PAD, 633 (44.8%) were women and the mean age was 70.8 (standard deviation, 13.3) years. Severe PAD was identified in 283 (20.0%) patients and poorly compressible vessels were identified in 350 (24.8%) patients. Only 32/283 (11.3%) patients with severe PAD and 68/350 (19.4%) patients with poorly compressible vessels were receiving four guideline-recommended therapies. Revascularization 1-year event rates were 32.4% among patients with severe PAD. One-year amputation event rates were 13.9% among patients with poorly compressible vessels. Poorly compressible vessels were associated with an increased risk of amputation (adjusted hazard ratio [aHR], 3.12; 95% confidence interval [CI], 2.16-4.50), but not revascularization (aHR, 0.91; 95% CI, 0.69-1.20). Severe PAD was associated with revascularization (aHR, 2.69; 95% CI, 2.15-3.37), but not amputation (aHR, 1.30; 95% CI, 0.82-2.07).
Conclusions:
The authors concluded that community-dwelling patients with severe PAD or poorly compressible vessels have high rates of revascularization and/or limb loss. They also concluded that guideline-directed therapies were largely underutilized in this population.
Perspective:
This study highlights the high degree of morbidity associated with severe PAD or the presence of poorly compressible vessels. Importantly, it confirms that more severe forms of PAD are associated with worse outcomes. Nonetheless, well-established therapies (antiplatelet medications, statins, antihypertensives, and smoking cessation) are grossly underutilized. With the advent of newer therapies (e.g., rivaroxaban 2.5 mg BID and PCSK9 inhibitors) promising improved limb outcomes among PAD patients, it is important to first initiate standard therapies with single antiplatelet medications, high-intensity statins, blood pressure control (possibly with ACE inhibitors or ARB medications), and tobacco avoidance.
Keywords: Amputation, Angiotensin Receptor Antagonists, Angiotensin-Converting Enzyme Inhibitors, Ankle Brachial Index, Antihypertensive Agents, Blood Pressure, Electronic Health Records, Hypertension, Myocardial Revascularization, Outcome Assessment, Health Care, Peripheral Arterial Disease, Platelet Aggregation Inhibitors, Secondary Prevention, Smoking, Smoking Cessation, Vascular Diseases
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