Importance of early diagnosis for Peripheral Arterial Disease (PAD) prevention

Cardiovascular diseases (CVDs) are a fairly insidious group of medical conditions that often manifest symptoms when they are already in the more advanced stages, complicating effective treatment and prevention and mitigation of adverse effects for the affected individuals. Peripheral artery disease (PAD) is no exception and only proper and early diagnosis can avert serious complications.

Despite being less talked about than other CVDs like coronary artery disease (CAD) or stroke, PAD is a serious medical condition that should be given far more attention than it currently enjoys. It is estimated that in the year 2010 more than 202 million people had PAD – today that number is likely far higher for a variety of reasons [1]. First and foremost, if we start at the non-modifiable spectrum of factors, is general ageing of the population (older individuals have a higher prevalence of PAD), which is quickly followed by the single biggest modifiable risk factor for CVDs in general – smoking [2].

Rates of tobacco smoking might be declining or have levelled off in the developed, high-income countries, but the same can’t be said for low and middle-income countries, where they are rising and present a growing public healthcare problem [3]. The same could be said for PAD, but we don’t really know how many people have it, since many of them are asymptomatic, have atypical symptoms or they are masked by other medical conditions. There are accurate and reliable diagnostic tools and methods, but awareness about them is low and they are often underutilised.

Why is early diagnosis of Peripheral Arterial Disease (PAD) important in primary care?

Failure to diagnose PAD in a timely manner is worrisome not only from the perspective of the disease itself, but also overall health and mortality. Namely, PAD is an important indicator of overall cardiovascular health due to its underlying pathophysiology – atherosclerosis. If it’s present in the arteries in the lower extremities, it is highly likely that it can found in other arterial beds, too.

This notion is well supported by ample evidence. Research has shown that between 22 to 42% of individuals with CAD also have PAD and those individuals fare worse (in health terms) than patients with only CAD, the worst killer amongst the CVDs and by itself (more than 9.43 million deaths in 2016) [4, 5, 6, 7, 8]. As for the predictive value of PAD, more specifically the ABI score (one of the best methods for diagnosing PAD) – it is well established that it can improve the accuracy of cardiovascular risk prediction beyond the FRS (Framingham risk score) [9].

Preventive screening of patients on the basis of their ABI score is just the thing that many primary care physicians should be doing when examining their patients: either as a part of periodic checkups or when patients come into practice with specific symptoms. However, that’s exactly how many patients with PAD get diagnosed: physicians suspect possible cardiovascular issues and refer the patient to a cardiologist who performs a more comprehensive examination.

Patients with PAD are at a significantly higher risk of death in general with estimates of 5-year mortality in the ballpark of 30% (versus 10% for control group without PAD).

Needless to say, many times general practitioners, being allotted only a few minutes for each patient, fail to detect symptoms, save for the most obvious ones, of more subtle CVDs, particularly PAD. Late or even no diagnosis carries a hefty price: patients with PAD are at a significantly higher risk of death in general with estimates of 5-year mortality in the ballpark of 30% (versus 10% for control group without PAD) [10]. About three quarters of those deaths are of cardiovascular nature.

The foundation for prompt and accurate diagnosis is, of course, knowledge of both risk factors for PAD and most common symptoms. Smoking is one of them. Prevalence of symptomatic PAD is 2.3 times greater in current smokers (in comparison with non-smokers) and 2.6 times greater in former smokers [11]. It should be noted that females are affected far worse than males: female smokers are 20 times more at risk than females who have never smoked [12].

Another important risk factor is diabetes since (at least) between 20 to 30% of patients with PAD also have diabetes [13]. More specifically, intermittent claudication, the most common and typical symptom for PAD, is 3.5 times more prevalent in diabetic males and 8.6 times more prevalent in females (in comparison with non-diabetic populations for each gender) [14]. There are other symptoms, however.

Visual appearance of affected limbs can be different from healthy ones, starting with a blueish or pale hue of the skin when the leg is in an elevated position [15]. Toenails can be malformed or have noticeably stunted growth (this should be checked with the patient) due to diminished flow of nutrients in the blood and legs can be completely hairless. Skin itself can be cold and have a scaly texture and shiny appearance.

Far more tell-tale signs are arterial insufficiency ulcers (ischaemic ulcers), which are indicative of an advanced stage of PAD and represent 10 to 30% all cases of lower-extremity ulcers [16]. Distinguishing between them and venous ulcers, which are the most common type of (leg) ulcers and require a vastly different treatment approach, can be challenging – the most convenient and easiest way is on the basis of an ABI score.

There are two main methods of measuring ABI: with a Doppler probe or an oscillometric device. The latter is particularly suitable for use in general practice as it can perform the measurement very fast and doesn’t require specialised training [17]. Coupled with detailed knowledge of the patient’s medical history, general practitioners are in an ideal position to identify the disease while it is still in the early stages and can be managed and treated with a lesser impact on the patient’s quality of life (and rather inexpensively). The later the diagnosis and the more time it passes from diagnosis to proper treatment, the greater are the associated costs, especially if the patient has other cardiovascular issues (which is often the case).

Armed with at least a rudimentary knowledge of the epidemiology and symptomatology of PAD and proper diagnostic tools, general practitioners should be the first line of defence against PAD.