SHOWME-PAD (Peripheral Artery Disease)

Peripheral arterial disease (PAD) is a burdensome condition that affects 10% of the population and increases to 15-20% among those ≥70 years. In PAD, the underlying pathophysiologic process, atherosclerosis, presents itself as blockages in patients' leg arteries that prevent adequate blood flow and can result in burning calf (or buttock) pain while walking and that is relieved upon rest ('intermittent claudication'). In extreme cases, PAD can progress to critical limb ischemia, characterized by ulceration, gangrene, and threatened limb viability. Patients with PAD have significant atherosclerotic risk factors and impaired health status - thus creating 2 therapeutic goals, prevention of cardiovascular events and improved symptom control and quality of life. While the onset of PAD tends not to be as abrupt as for other cardiovascular conditions, such as stroke or myocardial infarction, leg symptoms can severely affect patients' health status (their symptoms, functional status, and quality of life). In addition, patients' risk of having a cardiovascular event is disproportionately high, as compared with other cardiovascular diseases. One-year cardiovascular event rates - including cardiovascular death, myocardial infarction, or stroke, or other hospitalizations for atherothrombotic events - are estimated to be over 21% in patients with PAD, as compared with 15% for coronary artery disease and stroke.9 Mortality rates are 15-30% 5 years after diagnosis. Part of these disproportionate event rates may be explained by under recognition and under treatment of PAD and its underlying atherosclerotic process. Finally, PAD not only impacts patients' individual lives and their families; it also has a tremendous impact on society at large. It is estimated that annual costs associated with vascular-related hospitalizations in PAD patients in the US exceeds $21 billion.

The primary treatment goals for PAD are symptom relief, quality of life improvement, and cardiovascular risk reduction. Several treatment options are available for PAD, ranging from invasive revascularization procedures, including peripheral percutaneous intervention (PPI) and surgical revascularization to non-invasive options, including supervised and home-based exercise therapy, PAD-specific medications, and cardiovascular risk management. While there is no "gold-standard" treatment for PAD, less invasive options are recommended as a first-choice treatment. Despite these recommendations, invasive procedures are often first offered to patients, with no alternative options being discussed. In treatment scenarios with a lot of clinical equipoise (i.e. uncertainty about what treatment would be best) and a rapidly growing market for newly-introduced technologies, including medical devices for invasive PAD procedures (e.g. stents for endovascular treatment), with limited performance measurement and accountability criteria, there is a high risk of unwanted variation in treatment practices, misallocation of treatments, and unnecessary costs.

Given this context, some of the current challenges in current PAD care include: 1) limited access to the evidence-base in routine clinical care for patients and providers; 2) the potential mismatch of PAD treatments to patient preferences and profiles; and 3) patients not being informed or engaged in medical decision making. These challenges may leave patients uninformed about treatment risks and benefits, increase the risk of misallocating treatments to patients, and may unnecessarily increase costs. A very promising strategy to overcome these challenges is the use of evidence-based, decision support tools. Importantly, it is currently unknown whether patient-centered PAD decision-tools can be designed to improve the alignment of patients' values with respect to their treatment choice and whether these tools can improve patients' knowledge and access to the evidence-base related to PAD treatment and outcomes. The critical next step, therefore, is to create such tools and pilot their implementation as a foundation for broader integration of precision medicine and shared decision-making in clinical care.

Shared decision-making takes into account the latest evidence about all available treatment options and their outcomes, as well as patients' values and preferences with regards to treatment and potential outcomes that matter to them. Shared decision-making is extremely useful in treatment situations where there is clinical equipoise and where the choice of treatment should be greatly influenced by patients' preferences. Decision aids that facilitate this process of shared decision-making, have been consistently associated with better knowledge about the disease and treatments, less decisional conflict, and potential cost savings due to less invasive options being preferred by patients.