Peripheral arterial disease (PAD) affects individuals the world over. Some are more likely to be afflicted due to greater prevalence of risk factors and, depending on their socio-economical status and the organisation of their national health system, they may suffer worse outcomes. Despite the tone, however, this statement doesn’t apply only to developing countries since significant prevalence of PAD can also be found in developed countries.
There were an estimated 236.62 million patients worldwide with PAD (also referred to as lower extremity arterial disease or LEAD) in 2015 alone, up from 202 million in 2010 [1, 2]. See our blog The prevalence of Peripheral Arterial Disease for more information about the global prevalence of PAD. This trend of growing prevalence is likely to continue for the foreseeable future, due to the projected rise in the number of important risk factors such as the ageing of the population but also diabetes mellitus (more than 451 million patients in 2017 and projected to rise to 693 million in 2045) [2, 3]. The latter is particularly worth emphasising, as its deleterious effects on the cardiovascular system are especially prominent in PAD, aggravating symptoms, increasing the risk and severity of adverse outcomes, and hampering effective treatment.
In France, a country with 67 million inhabitants, it is estimated that around 1 million people are suffering from PAD . The exact number is difficult to know as, like all around the world, PAD is underdiagnosed.
The statistics in France are that between 6 to 12% of the general population has PAD and it reaches 20% in people older than 70 years old. This percentage is even higher in patients with cardiovascular risk factors such as diabetes, hypertension, smoking, high cholesterol or previous cardiovascular diseases. Indeed, in patients with cardiovascular risk factors the prevalence of PAD reaches 40% .
The international prospective observational registry REACH has recruited over 55,000 patients in 44 countries . The recruited patients were at least 45 years old and had already been diagnosed with at least one atherothrombotic disease such as coronary artery disease (CAD), carotid stenosis or PAD. The study showed that 25% percent of patients with past CAD also had PAD. This number increased to 30% in patients with a history of vascular stroke . Looking at the statistic from the other end, 60% of patients with PAD also had evidence of plaques in their carotid or coronary arteries.
Generally, if atherosclerosis is present in the lower extremities, it is highly likely that it could also be found in other arterial beds. For example, research has shown that between 22 and 42% of individuals with coronary artery disease (CAD) also have PAD and those individuals fare worse (in health terms) than patients with only CAD [8, 9, 10, 11]. As for the predictive value of PAD, more specifically the ABI score (one of the best methods for diagnosing PAD), it is established that it can improve the accuracy of cardiovascular risk prediction beyond the FRS (Framingham Risk Score) .
There are several reasons why PAD is underdiagnosed. One is due to the previous methodology used to assess ABI (Ankle-Brachial Index), an index giving information about the presence of stenosis in the leg artery. But we will talk about that later.
The other main reason for this underdiagnosis is that, like in other developed countries, about 70% of those affected have an asymptomatic form of PAD . The symptomatic form of PAD refers to patients who claudicate, or have pain in their leg even when resting or sleeping, or have some form of lower limb ischaemia. However, many patients are not diagnosed. It could be because they do not mention to their physician the pain they experience while walking. They minimise the pain because they attribute it to old age, and do not know that it could be a symptom of an important cardiovascular disease. It could also be because they have a pathology that prevents them from walking and hence from feeling any discomfort when walking. This is called masked LEAD . Typically, masked LEAD can be encountered in frail elderly people who cannot walk, in diabetic patients with peripheral neuropathy who do not feel any pain, or heart failure patients who experience shortness of breath even before pain in their leg.
As PAD can be asymptomatic, it is crucial to screen patients at risk in order to organise proper health management to reduce or postpone its cardiovascular consequences. Measurement of Ankle Brachial-Index is the tool used for diagnosis of PAD. It is based on the measuring systolic blood pressure in the ankle and comparing it to upper arm blood pressure. An ABI below 0.9 is considered a diagnosis of PAD. Below 0.5, it is critical PAD.
Not all individuals are equally at risk. Those with a generally healthy lifestyle are at lower risk and it is not economically and medically productive to screen them. However, persons who are at risk do benefit from screening and should be given priority when screening for PAD. The French National Authority for Health (Haute Autorité de Santé – HAS) therefore recommends systematic screening for PAD in patients at risk on the basis of ABI.
Unfortunately, despite these national guidelines for systematic screening, ABI is not routinely measured in French primary or even secondary points of care. This fact is not only true in France but also all around the world. A study of ABI assessment utilisation in PAD screening of patients with leg ulcers (patients who are much in need of ABI assessment) found that 40% of patients had not received an assessment, or it was unclear whether a recording had been taken. The study also found that nearly 31% of patients with venous leg ulcers involved in the study were not receiving the necessary compression therapy .
A study in France has investigated the cost of late PAD diagnosis . The cost to the national health care system of patients with PAD was compared to the cost of patients with any comorbidities other than PAD. The excess cost reached €11,000 per patient and per year. If we multiply that cost by the number of PAD patients, one can easily calculate the huge burden of PAD on the French National Health Insurance Fund.
However, we should not blame physicians for the late diagnosis of PAD. The reason why ABI is so seldom performed, even in patients at risk, is due to the historical method of measuring ABI. When it was performed manually with Doppler, it required time, expertise and experience. During their routine medical consultations, physicians do not have the time to perform a test which can take up to 30 minutes when done manually. Fortunately for patients and their physicians, there are now modern automated devices available. With MESI ABPI MD or MESI mTABLET ABI, ABI can now be accurately measured in 1 minute.
Hopefully, the availability of such equipment will help to better identify PAD patients. Early health advice, and pharmacological and surgical treatment will better prevent and reduce co-morbidities associated with PAD. In France, to encourage better management of the disease, the assessment of ABI is a reimbursed procedure by the National Health Insurance. Doctors can charge €21.12 by using the CCAM code: EQQM006 .
Accurate and timely diagnosis of PAD on the basis of ABI score is paramount for effective treatment and conducive to decreasing cardiovascular morbidity and mortality.