The High Cost Of Peripheral Artery Disease And Critical Limb Ischemia

The High Cost Of Peripheral Artery Disease And Critical Limb Ischemia

Abstract

Despite the high prevalence of peripheral artery disease (PAD), this chronic disease continues to be underestimated, underdiagnosed, and undertreated. PAD is frequently ignored or dismissed as “a lifestyle disease.” Underdiagnosis and undertreatment result in high patient morbidity and mortality. Coronary and cerebrovascular disease are major contributors to this morbidity and mortality. The economic burden of PAD is significant, exceeding that of many other common chronic diseases. Earlier diagnosis and appropriate treatment of leg symptoms, as well as comorbid cardiovascular disease and diabetes, could reduce the economic cost.

Peripheral Artery Disease Prevalence

 In 2015, the prevalence of PAD was almost 20 million.1 Comparing this number with the U.S. prevalence of other chronic diseases, only diabetes (36 million) is more common.1,2 In comparison, stroke has a prevalence of 7.2 million.3 Even coronary heart disease (CHD) and all cancers afflict fewer U.S. individuals, at 16.5 million and 15.5 million respectively, than lower limb atherosclerotic disease.3,4 Despite the high rates of PAD, it frequently is not included in reviews of cardiovascular disease.5,6

Figure 1. 2015 U.S. Prevalence of Chronic Disease (Millions)
Source: Yost,1 Menke,2 Benjamin,3 American Cancer Society4 and Alzheimer’s Association.7

Economic Cost

In 2015, the total economic cost of PAD was between $224 and $414 billion.8 The lower figure represents annual per patient costs in the U.S. reduction of atherothrombosis for continued health (REACH) registry.9 The higher figure is the per patient cost in the Margolis managed care study.10 

Reported costs in these two studies were inflated to 2015 dollars employing the appropriate medical care components of the U.S. consumer price index (CPI).11-13 Unless otherwise noted, all other cost data in this article has been inflated to 2015 dollars.

Both the REACH Registry and the managed care study included inpatient and outpatient medical costs.9,10 The key difference between the two studies reflects the inclusion of all-cause hospitalization costs in the Margolis study.10 In contrast, per patient costs in REACH were PAD and cardiovascular hospital costs only.9

Majority of Costs Are Inpatient

Hospital costs account for the majority (65%-88%) of PAD costs, or $147 billion in the REACH study and $363 billion in the managed care study.8-10 Two Medicare studies also found that nearly 90% of PAD treatment costs were inpatient.14,15

Since hospital costs account for a bit less than one-third of total U.S. healthcare expenditures, PAD hospital costs are 2-3 times the national average.16

Non-PAD costs account for a significant portion of hospital costs. In patients hospitalized for cardiovascular reasons, 43% of costs are non-PAD costs.9 However, if we examine all-cause hospitalizations, then non-PAD costs account for almost 90% of the total.10,14

Frequent Presence of Polyvascular Disease Increases Costs

Most PAD patients have polyvascular disease. According to REACH, just 30% of PAD patients have PAD alone. The rest have some combination with coronary artery disease (CAD) and cerebrovascular disease (CVD). Significantly, over 60% have CAD either alone, or in combination with cerebrovascular disease.17  

Polyvascular disease increases the cost. In 2015, PAD alone cost about $11,300 per year, or about the same as PAD with CVD. Costs rise to exceed $15,000 in patients with both PAD and CAD. The highest costs are generated by PAD patients with both CAD and CVD, representing almost $20,000 per year.17

Medicare Pays for Majority of the Peripheral Artery Disease Bill

Medicare and Medicaid pay 80% of the PAD hospital bill. Reflecting the preponderance of elderly patients, Medicare alone pays 71%.18 In contrast, Medicare pays 46% of the national hospital bill, with Medicare and Medicaid combined accounting for 60%.19

In the 2003-2012 period, between 10%-21% of Medicare patients were treated for PAD.20,21 The average expenditure per patient in 2015 dollars was between $22,756 and $72,159.8,14,15 This range reflects the definition of PAD, as well as the types of treatments included in the studies. Importantly, the higher number includes long-term care costs, as well as emergency and other services.15

Medicare spending of $72,159 per PAD patient is 6 times higher than the spend on an average beneficiary, $11,951.8,15,22

Economic Burden of Peripheral Artery Disease Exceeds Other Chronic Diseases

Comparing the cost of PAD to other chronic diseases, the economic burden is high and exceeds that of diabetes, CAD, and all cancers combined.3,4,8,23

Figure 2. 2015 Annual Economic Burden of Selected Chronic Diseases ($ Billions)
Source: Benjamin,3 American Cancer Society,4 Yost,8 Mahoney9 and American Diabetes Association.23

The $176 billion cost of diabetes represents the direct cost of the disease in 2012.23 Recently published data found that, by 2017, costs had increased to $237 billion, or $16,752 per patient.24 If we conservatively compare 2015 PAD costs to 2017 diabetes costs, the economic cost of PAD at $224-$414 billion is at least as high as diabetes and likely higher. 

Critical Limb Ischemia Prevalence

Between 2.0 and 3.4 million of those with PAD have critical limb ischemia (CLI), the most severe form of the disease.1 These figures represent prevalent disease, not the number diagnosed and treated. Only a fraction, or approximately 700,000 to 800,000, are treated with revascularization or amputation.25 

Cost of Critical Limb Ischemia

The cost of treating incident CLI cases in Medicare has recently been estimated at $4.2 to $12.0 billion.26,27 However, all-cause costs of prevalent disease in all age groups are considerably higher, estimated at $220 to $300 billion.28 The difference in the above cost estimates reflects the fact that the higher numbers are based on prevalent cases (3.4 million) in all ages rather than incident disease in Medicare. In addition, the costs to treat cardiovascular disease, diabetes, and all other comorbidities are included, which add significantly to the total economic burden.28 

Factors Driving Up Costs

Interventional treatment of CLI is costly. In a recent analysis of Medicare CLI patients, 2016 costs per patient were $49,200 for surgical bypass, $49,700 for endovascular, and $55,700 for major amputation.27 However, interventional therapy is only one of many factors that increase the economic burden of CLI. Notably, these factors are all modifiable or preventable.28

Costs Increase with Disease Severity

Treatment costs for both PAD and CLI increase with disease severity. The inpatient cost of treating intermittent claudication (IC) in 2015 was $19,300. In contrast, the cost of treating CLI was almost $30,300.29 A recent German study also demonstrated that average inpatient costs for CLI treatment were higher than those for PAD patients in Rutherford Category 1-3.30

Within CLI, costs increase with severity of ischemia. Inpatient treatment of a patient with rest pain (Rutherford 4) costs approximately $24,000 and increases to $28,000 for a patient with ulcers (Rutherford 5). Inpatient costs for patients treated at the most severe stage, Rutherford 6, approach $40,000.26 German data also show a similar pattern of treatment costs increasing with increasing severity of CLI.30    

These data suggest that earlier diagnosis and treatment at less severe stages of ischemia could reduce the economic burden of PAD and CLI.28

Diabetes

Age and diabetes are the key risk factors for CLI.31,32 Although age is not modifiable, the consequences of diabetes are with optimal glycemic control.33  

Diabetes is an even stronger risk factor for CLI than it is for less severe lower limb disease. While diabetes increases the risk of PAD by 2-4 times, it increases the risk of CLI by 7-8 times.21,34-37

Diabetes is one of the major comorbidities in CLI. Whereas 14% of the general population is diabetic, approximately 60%-80% of the CLI population has diabetes.2,28,31 The co-prevalence of these two diseases has implications for CLI severity and morbidity, as well as for treatment costs.

Diabetics have more severe ischemia and are more likely to present with more severe disease, characterized by ulcers and gangrene.31,38,39 Critical limb ischemia develops suddenly in diabetics.40 Diabetics with CLI have more amputations and a 28 times higher risk of amputation.41-49 The risk of amputation increases with the severity of diabetes measured by HbA1c.50-52 The rate of amputation also increases with age.49 The presence of diabetes increases CLI costs.53-55

Polyvascular Disease

The majority of CLI patients have polyvascular disease.28 A recent study of Medicare patients found that almost half of CLI patients had CAD.27 Other studies in various CLI populations found that the prevalence of CAD was 48%-85%, while that of CVD was 16%-25% respectively.21,27,42,56-58 Approximately 20%-30% of CLI patients suffer from congestive heart failure (CHF).21,56,58,59

Cardiovascular disease (including hypertension complications) accounts for over 7% of CLI admissions. CHF represents 3.5% of CLI admissions, while myocardial infarction (MI) accounts for 1.84%.60 These cardiovascular hospitalizations and revascularizations add significantly to all-cause costs.28

Major adverse cardiac events (MACE) increase with disease severity, more frequently occurring in CLI patients than in those with IC.58 MACE is defined as nonfatal MI, nonfatal ischemic stroke, or cardiovascular death. Over half of deaths in CLI patients are due to cardiovascular causes.58 Despite this, CLI patients continue to be undertreated for their cardiovascular risk factors, even in comparison to IC patients.58,61,62

Suboptimal Risk Factor Management

PAD is considered a coronary artery disease risk factor equivalent. Recommended risk factor modification therapies include smoking cessation, aspirin, statins, and antihypertensives, as well as optimal glucose control in those with diabetes.61,63 

Despite these guideline recommendations and the high prevalence of both coronary artery and cerebrovascular disease, CLI patients are undertreated for their risk factors.33,61 Statins, antiplatelets, and antihypertensives are underutilized. 33,61 Glucose is inadequately controlled in 40% of CLI patients and smoking persists in 29%-52%.33,36 Overall, only about one-third of CLI patients receive optimal medical management with all risk factor modification therapies. 33,61  

Inadequate risk factor management increases both MACE and major adverse leg events (MALE). 33,61 One recent study concluded that suboptimal risk factor management increases the risk of amputation and/or death by 8 times. 33 The resulting adverse cardiac and leg events drive up CLI costs. The 2018 cost of MACE in CLI patients is conservatively estimated at $17.5 billion.28  

Unplanned Readmissions

At 20%-27%, 30-day CLI readmissions are high and exceed the 12% rate for stroke and 15% rate acute for MI.26,29,64-67 At 6 months, almost 60% of CLI patients are readmitted. The majority of these readmissions are unplanned.26,64 

All-cause readmissions are higher for CLI than for PAD and increase within CLI by Rutherford Category.26,29,67 For example, 30-day readmissions for gangrene are 25.0% versus 14.8% for rest pain.26  

Significantly, less than one-third (21%-33%) of readmissions are due to primary CLI.26,64 The majority of readmissions are for non-CLI reasons such as procedure complications, infections, diabetes related non-vascular problems, and cardiovascular events. 26,64,65

High rates of unplanned readmissions increase CLI costs.26,65 A recent study estimated that, in 2016, CLI readmissions cost $624 million. The authors calculated that a 1% reduction in readmissions could save $15 million annually.26 Unplanned readmissions also increase MALE.68,69 Major adverse limb events add to the CLI cost burden.28,70

Most of the factors that lead to CLI readmissions are modifiable.68,71 Improved focus on prevention and early diagnosis and treatment of infection could reduce readmissions and associated costs.26 Meticulous surgical technique and peri-procedural monitoring could decrease procedure complications.65,68,71 Optimal cardiovascular risk factor management and diabetic care could decrease cardiovascular and diabetic readmissions. 65,68,71

Diagnosis and treatment of CLI at less severe stages could also reduce readmissions and costs. Since major amputation is a risk factor for CLI readmissions, replacing amputation with revascularization procedures could favorably impact readmission rates.28,64

Conclusion

While interventional therapy for PAD and CLI is costly, with primary major amputation being the most expensive interventional therapy, other primarily modifiable factors add to the economic burden of the disease. These include delay in diagnosis and treatment until the later stages of the disease, the high presence of polyvascular disease, suboptimal treatment of cardiovascular risk factors, and high rates of unplanned readmissions. Optimal management of risk factors and comorbid diseases (diabetes, CAD, CVD), as well as improved management of preventable issues like procedural complications and infections, could significantly reduce the economic burden.

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