Peripheral Arterial Disease (PAD) might not be the most prominent cause of premature mortality, either on its own or as a part of Cardio-vascular Diseases (CVDs) in general, which are the leading cause of mortality worldwide. Its presence however is indicative of possible systemic atherosclerosis and is therefore an important independent predictor of cardiovascular and overall mortality.
Studies have shown that ABI (Ankle-Brachial Pressure Index) measurements (the most convenient and cost-effective diagnostic method for PAD) can improve the accuracy of cardiovascular risk prediction beyond the FRS (Framingham Risk Score) . Furthermore, patients with PAD are at a significantly higher risk of mortality in general, with estimates of 5-year mortality in the region of 30 % (versus 10 % for the control group without PAD) – about 75 % of those deaths are cardiovascular in nature .
It is also of no surprise that many individuals with PAD also have other CVDs, like Coronary Artery Disease (CAD), which is the single largest cause of death worldwide (amongst CVDs and by itself) . Research has indicated that between 22 and 42 % of patients with CAD also have PAD and those individuals fare worse (in health terms) than patients with only CAD [4, 5, 6, 7]. PAD is also a good predictor of carotid artery stenosis and the consequent risk of stroke .
With such a well-documented indicative value for cardiovascular health one would expect that healthcare organisations worldwide would dedicate more resources for the screening and treatment of PAD, especially for at-risk groups. Unfortunately, nothing could be further from the truth as many individuals with PAD go undiagnosed until the disease is already in an advanced state and/or has started to exhibit overt symptoms or the patient has been hospitalised due to some other CVD and PAD is diagnosed incidentally. At that stage PAD can be difficult to treat, with complications ranging from arterial insufficiency ulcers (ischaemic ulcers) to gangrene and subsequent amputation.
The Number of Undiscovered Patients with Peripheral Arterial Disease (PAD)
As with many other diseases there are no exact numbers when it comes to the worldwide prevalence of PAD, only estimations: about 202 million individuals in 2010 had PAD . Today that number is likely to be higher as PAD is more common in the elderly (one of risk factors) and world populations which, at least in the developed world, are rapidly ageing. The only thing more worrisome than the growing number of patients with PAD is the fact that many go undiagnosed despite advances in diagnostic methods, specifically for large scale screening, and awareness of risk factors.
There were about 8.5 million patients with PAD in the United States in the year 2000; how many of them there are today is a mystery, but this number is likely to be higher . Such large numbers are invariably connected with significant healthcare costs, which are not least due to the difficulties in treating advanced stage PAD. It was estimated that the annual medical expenses for patients with PAD were $11,553 (which is more than a twofold increase in comparison with patients without PAD) during the period between 2011 and 2014 .
A considerable fraction of these costs is related to treatment of arterial insufficiency ulcers (ischaemic ulcers). These types of ulcers are less prevalent than those caused by Chronic Venous Disease (about 72 % of all cases), thus accounting for only 10 to 30 % of such cases, but they are notoriously difficult and expensive to treat . For comparison, a study of Medicare expenses for treatment of chronic non-healing wounds in 2014 cites the overall cost of treating arterial ulcers at $2.08 billion, while venous ulcers accounted for only $0.72 billion (nearly three times less) .
Economic impact aside, the gravest outcome of PAD is lower-extremity amputation and the increased risk of subsequent mortality. Diagnosis of Critical Limb Ischaemia (CLI), the advanced stage of PAD that manifests as ischaemic rest pain, arterial insufficiency ulcers and gangrene, is associated with a significant increase in mortality. Reported mortality rates range from 20 % for the 6-month time period from the time of diagnosis up to 50 % for 5 years after diagnosis [13, 14, 15]. Amputation rates are consequently fairly high, from 10 to 40 % (for a 6-month period) [16, 17].
Between 2000 and 2008 there were 186,338 lower-extremity amputations (for about 3 million hospitalised patients) due to PAD in the United States (US Medicare data).
Situation in Europe is not much better, both with regards to the prevalence of PAD and its socio-economic impact. It is estimated that about 20 % of middle-aged (65–75 years) individuals in the UK have PAD, but only a quarter of those have symptoms typical for the disease .
As in the United States, costs associated with treatment of PAD are significant, ranging from £1,087 for general (conservative) treatment to £5,378 for femoral-tibial bypass surgery and £5,994 for amputation per patient . The precedent for amputation is of course diagnosis of CLI: each year there are between 500 and 1,000 new cases per one million inhabitants that (cumulatively) cost the NHS (National Health Service) more than £200 million . Moreover, PAD is the leading cause of amputations, accounting for 90 % of 5,000 major leg amputations annually .
Prevalence numbers and morbidity are similar in other European countries such as Sweden. Studies have shown that almost a fifth of elderly (60–90 years) inhabitants have PAD and that females have higher rates of the asymptomatic form of the disease . Costs are comparable or slightly higher; treatment of patients with PAD in the period between 2006 and 2014 costed, on average (mean total health costs), €10,357 .
It is worth highlighting the fact that costs were significantly higher for those with other comorbid CVDs such as CAD and ischaemic stroke (IS); €14,916 for those affected with all three diseases, €12,884 for those with IS and €12,290 for those with CAD . The reported annual amputation rate due to CLI is between 12 and 71 per 100,000 inhabitants .
The socio-economic costs of PAD are great and are projected to increase in the future, necessitating preventive screening on the basis of ABI and timely treatment and management.