Guidelines, appropriateness, and quality of care in PAD
Symptomatic PAD is among the most common reasons for referral to a vascular specialist. The volume of invasive procedures for PAD, and the attendant cost, has risen dramatically over the last decade. The majority of these interventions are for treatment of intermittent claudication (IC). Patients with IC have a broad range of disabilities and comorbid conditions. Medical therapy, smoking cessation, and exercise are of proven value for symptom improvement and long-term vascular health. In appropriately selected patients, revascularization for IC can relieve pain and improve ambulatory function. As a vascular surgeon keenly interested in PAD, I perform both open and endovascular interventions for IC in my practice.
Recent reports have highlighted rising concerns about the overuse of invasive procedures in PAD. A New York Times article1 cited the dramatic growth of stent procedures, raising a red flag among multiple stakeholders and consumers of vascular care. Although a closer look at the NY Times data highlights the explosion of stenting for venous disease, much of the subsequent discussion focused on PAD treatment, with its decade-long trend of rising volumes.
Another recent report2 documented the growing volume and costs of office-based percutaneous interventions for PAD in the United States, coincident with changes in Medicare reimbursement that greatly incentivized providers. This has turned the spotlight on office-based angiography suites, and how they are monitored. Improved, less invasive technology is often cited as a rational basis for offering intervention more readily to PAD patients. Unfortunately, the data on efficacy of interventions in IC is shockingly limited, leaving a wide gap in evidence supplanted by poor quality studies, overemphasis on technical success, market forces, and naked economics.
Just prior to the publication of the New York Times article on stent use, the SVS released a clinical practice guideline on the management of asymptomatic PAD and claudication.3 Systematic evidence reviews were undertaken4,5 and an expert panel of clinicians developed a list of specific recommendations. Medical therapy and exercise, preferably supervised exercise, were strongly recommended as first-line therapy for IC. Revascularization was considered reasonable for those patients with significant disability, acceptable risk, and after pharmacologic or exercise therapy have failed. An important recommendation in the guideline addresses a minimal effectiveness standard for revascularization in IC. Physicians should carefully consider the likelihood of functional benefit of a procedure based on patient risk, degree of impairment, and anatomic/technical factors that are known to impact patency.
The guideline suggests that a recommended intervention for IC should have a minimum expectation of >50% likelihood of sustained benefit for at least 2 years. At a recent local vascular symposium attended by more than 100 vascular providers, I asked the following question: “If you were a PAD patient considering an invasive procedure for claudication, what is the minimum likelihood of durable walking improvement you would expect?” The choices were >50% likelihood for at least 1 year, 2 years, or 3 years. Nearly 80% voted that they would want a 3-year, 50% minimum “guarantee” to consent to treatment. That seems quite rational to me.
Surgical and endovascular interventions for even advanced forms of aorto-iliac disease would generally meet the “>50% patency for at least 2-3 years” bar. But infrainguinal intervention is quite a different story. Although technology continues to advance with drug elution and improved stent designs for femoro-popliteal occlusive disease (FPOD), it has been incremental. I think it is fair to say that 3-year durability of an endovascular intervention for extensive FPOD is much more the exception than the rule. Now let’s consider a bit of “claudication math”. FPOD is commonly bilateral and symmetric.
How does one approach bilateral significant FPOD in a claudicant? If an intervention of long segment FPOD has a 60% chance of patency for 2 years, what’s the likelihood of a successful patient outcome if both legs are treated? Since we can usually assume two good legs are required for walking, it would be 0.6 x 0.6= 0.36! The best treatment we have for FPOD is a vein bypass graft, with a 70%-80% 3-year outcome. Bilateral fem-pop vein bypass grafts would just make the 50%, 3-year minimum expectation threshold, at the expense of two open procedures with their potential complications and costs. All of this means what we have always known: that we need to choose very wisely when intervening for claudication to get successful and satisfying outcomes. The old dictum “stop smoking and start walking” should not be replaced by “lets do a Duplex and take a look at your blockage, then we’ll see.”
