Peripheral arterial disease (PAD) or lower-extremity artery disease (LEAD) as it is also called, may often be entirely asymptomatic, but that doesn’t mean it can’t be diagnosed using modern diagnostic methods. However, certain groups of patients are more at risk than others and should therefore be given priority before others.
The asymptomatic nature of PAD/LEAD (only 10% of patients have typical symptoms and up to 40% are symptomatic) goes hand in hand, if we are permitted to use this term for this insidious disease, with lack of knowledge about the harmful effects and complications of the condition itself and the additional deleterious consequences it has on a myriad of other diseases (primarily of cardiovascular nature) [1, 2].
There were an estimated 202 million patients with PAD in 2010 alone (today that number is likely far higher) and yet many physicians don’t screen for the disease, whether on the basis of a thorough physical examination (accuracy and reliability predicated on the examiner’s skill and experience) or using a modern diagnostic device (best option) . High prevalence is, of course, not the primary reason for the greater attention it deserves, but the life-threatening complications of late or un- or misdiagnosis and improper treatment.
For example, a comprehensive study conducted in the UK found that about 40% of patients with leg ulcers have not received an ABI assessment or it was unclear whether any recording was taken and that 31% of patients diagnosed with venous leg ulcers were not receiving compression therapy . This is a most troublesome finding as the Ankle-Brachial (pressure) Index (ABPI or ABI) measurement is an excellent tool for differentiating between the different types of ulcers and assessing the dominancy of a particular type (in patients with ulcers of mixed etiology).
In general (of all cases of lower-extremity ulceration) about 72% of ulcers are venous in origin, 10–30% are caused by PAD and between 15% and 25% are due to diabetes mellitus . Naturally, ulcers, especially of chronic, non-healing character, don’t usually just develop spontaneously and affect random individuals, which brings us to the question of patient risk groups, specifically those for PAD (since this is the topic of this blog post).
Why preventive check-ups can save a patient’s life?
The second important issue, besides the frequent asymptomatic presentation, of PAD is its association with several cardiovascular diseases (CVDs) which should come as no surprise in the light of indicative nature of the disease (possible atherosclerosis in other arterial beds). The connection between PAD and overall cardiovascular health is well researched and ABI score is recognised as an important indicator for improving the accuracy of cardiovascular risk prediction beyond the FRS (Framingham Risk Score) . Risk factors for development of PAD are, therefore, virtually the same as for many other CVDs, but some have more weight than others.
Overview of risk factors for PAD
- Smoking. The biggest risk factor for development of many CVDs, including PAD, is tobacco smoking (more than twofold increase in risk in comparison with those who have never smoked, although some subgroups, like females are even worse affected) [7, 8]. A more comprehensive summary of the negative effects of smoking on PAD is presented in “Effect of smoking on ABI” blog post.
- Diabetes. The other serious risk factor (complex treatment and management, coupled with a myriad of possible complications), which greatly increases the incidence and severity (major amputation rates are 5 to 15 times higher in diabetic than non-diabetic patients with PAD) of PAD . More on this topic can be read in the “Effect of diabetes on ABI” blog post.
- Age. An important risk factor as older individuals are statistically more likely to have PAD (10). Additional statistics are presented in the “Effects of age, weight and family history on ABI” blog post.
- Obesity. Unhealthy weight is a risk factor for many CVDs, not just PAD (11). This is further explored in the “Effects of age, weight and family history on ABI” blog post.
- Dyslipidaemia. Abnormal levels of blood lipids contribute to the atherosclerotic process (underlying mechanism of PAD) .
- Hypertension. High blood pressure is a risk factor for both the development of PAD and the severity of outcome (increased risk of ischaemic stroke and myocardial infarction) . The “Hypertension and peripheral artery disease” blog post contains more information on this topic.
- Family history. The genetic aspect of PAD is relatively poorly researched, but studies have shown that those individuals with a family history of the disease are at a greater risk . Details in the “Effects of age, weight and family history on ABI” blog post.
However, knowledge of risk groups is only one part of the equation for a formulating proper treatment and management programme, the other one being acquainted with the various subtle and overt symptoms associated with PAD (intermittent claudication being the most typical).
Brief overview of symptoms of PAD
- Intermittent claudication.
- Weak or entirely absent pulse in the legs and feet.
- The colour of the skin on the affected leg changing to a blueish or pale hue.
- Lower temperature in the affected leg (in comparison with the unaffected limb or the rest of the body).
- Scaly and shiny skin on the affected leg.
- Poor toenail and hair growth on the affected leg.
- Sores, ulcers and wound on the feet, usually non-healing in nature.
- Erectile dysfunction in men, especially if they are diabetic.
Now for the last three pieces of the puzzle that are required for a complete picture of PAD: diagnostic methods, treatment/management and possible complications. There are several diagnostic methods suitable for identifying PAD and assessing its severity, but some are more convenient and (cost) effective than others. Generally speaking, each attempt at PAD diagnosis should start with a physical examination and a detailed questionnaire (as is presented in the “18 questions to ask a patient to assess the risk of PAD” blog post) in order to determine whether the examined patient is a candidate for further examination with a diagnostic device (ABI assessment).
The standard method of measuring ABI is by using a Doppler probe and a sphygmomanometer (accuracy dependant on examiner’s skill), but there are far better options, like an oscillometric-plethysmographic device, which is especially suitable for preventive screening [15, 16]. Assessment on the basis of ABI is also suitable for other diagnostic purposes besides diagnosing PAD (researched in the “Arterial assessment as diagnostic tool” blog post).
Patients with abnormal ABI are either referred for additional examination, e.g. if they have incompressible arteries (common in diabetics), or start treatment. There are different approaches (subject to severity of the disease), ranging from relatively conservative management to invasive surgery (revascularisation) for patients with a more severe form of PAD. There is, however, much that patients can do themselves, like leading a healthier life (more on that in the “6 tips for patients with PAD” blog post).
Still, proper and comprehensive management of PAD can be difficult as many patients have comorbid conditions that may require modifications to the initial treatment plan. Some medical conditions are even made worse by comorbid PAD (presented with concrete statistics in the “Impact of peripheral arterial disease on other diseases”). One such example is diabetes: about 50% (some studies put that estimate at 76%) of patients with critical limb ischaemia (CLI), the most severe form of PAD with high mortality (20% mortality 6 months after diagnosis and 50% after 5 years), have diabetes and they fare worse than non-diabetics [17, 18, 19, 20, 21]. One of the complications of CLI is amputation, which naturally greatly affects the patient and requires, even in the very initial stage of breaking the news to the patient, a delicate approach (as presented in the “6 steps for delivering the patient news about limb amputation” blog post).
Patients in risk groups are particularly susceptible to PAD and often have worse morbidity and higher rates of adverse outcomes, including death. They are prime candidates for an ABI assessment, which should be followed-up by immediate treatment or periodic preventive screening and lifestyle modification.