Peripheral arterial disease (PAD) is a major vascular condition that decreases blood flow to the affected limbs; it is mostly caused by atherosclerosis, a progressive disease characterized by the intra-arterial accumulation of lipids and fibrous elements [1,2]. The PAD symptoms of claudication and critical limb ischemia (CLI) occur following the reduction of blood flow to affected limbs, with resultant resting pain and cramps [3-5]. Worldwide, more than 236 million people are affected by PAD, and the PAD burden could increase with population aging [6,7], as PAD prevalence consistently and globally increases with age, especially in older age groups [6,7]. In the United States, treatment of CLI symptoms in older patients (aged >65 years) with PAD incurs an estimated cost of US $1.2 billion yearly [8,9].

Vessel patency in the affected limb is essential for adequate blood flow, as vessel obstruction increases risk for amputation, mortality, and poor health-related quality of life [10-12]. Endovascular revascularization (EVR) by percutaneous transluminal angiography (PTA) is the preferred method to open affected vessels, thereby improving the clinical manifestations of claudication and CLI [13] and reducing major amputations of the affected limbs [14]. However, the prognosis of the surgical procedure is associated with procedural characteristics, such as method and target region, and patient characteristics, such as age, smoking, and comorbidities [15]. A systematic review revealed that major amputation events after surgical intervention were significantly related to comorbidities, such as cardiovascular disease, chronic kidney disease, diabetes, chronic occlusive pulmonary disease, dementia, and frailty [16].

Some patients with PAD have atypical presentation, without intermittent claudication or clear limb symptoms [4,9], and may attempt to alleviate limb symptoms by reducing physical activity, which may eventually cause a worse prognosis [4,17]. Thus, patients with asymptomatic PAD may not be properly diagnosed and may not receive adequate treatment [18,19]. Furthermore, chronic diseases such as PAD affect psychological well-being by inducing depression, anxiety, and low quality of life [20,21]. Pain and difficulty in walking distances and climbing stairs in patients with PAD are significantly related to quality of life [22] and well-being [23].

Understanding trends in the incidence, prevalence, and clinical manifestations of PAD and related procedures, treatments, and health outcomes are crucial for public health interventions. Thus, identifying the incidence and prevalence of PAD using recent national data may provide baseline data to facilitate the development of health promotion strategies and interventions for patients with PAD and public health promotion. However, most previous studies have examined the incidence and prevalence in Western countries [1,24], and PAD has been studied only as part of atherosclerotic disease [25].

Currently, studies on PAD in Eastern countries are scarce, which limits understanding of the global features of PAD. Moreover, few studies have investigated national data on health care utilization characteristics. This study used nationwide data obtained from the Health Insurance Review and Assessment (HIRA) Service of South Korea from 2011 to 2018 to investigate (1) trends in the incidence, prevalence, and treatment of PAD (eg, EVR events) and PAD-related amputations and in-hospital deaths and (2) health care utilization characteristics of patients with PAD.

This study identified the incidence and prevalence of PAD and PAD treatment trends, in-hospital deaths, and health care utilization in South Korea over the past 8 years through a retrospective analysis of national claims data.

The average PAD incidence was 2.91 per 1000 individuals from 2012 to 2018. Previously, a United States–based study used MarketScan data, which includes commercial, Medicare, and Medicaid health insurance data, to identify patients with a PAD or CLI diagnosis and found that the mean annual incidence of PAD was 2.34 [32]. A study conducted in the United Kingdom used a database of 11 million patients from 2000 to 2014 to search for symptomatic patients with PAD with at least 1 medical record in at least 2 years and found that the overall PAD incidence was 1.73 to 3.85 per 1000 individuals [33]. Our findings show that PAD incidence in South Korea was higher than in the United States and similar to the United Kingdom. Considering the characteristics of the participants, this study included claims with 1 PAD diagnosis in 8 years. However, if our analysis had used the same criteria as the study conducted in the United Kingdom, the PAD incidence in South Korea would have been lower.

The sex-stratified incidence and prevalence trends of PAD differed from those in previous studies and were higher in women than in men. The proportion of female patients with PAD ranged from 59.3% (60,552/102,153) to 61.6% (85,696/139,191), whereas for male patients, it ranged from 38.4% (53,495/139,191) to 40.7% (41,601/102,153). In a previous study, PAD incidence was 23.05 per 10,000 person-years in males, which was higher than the reported 12.37 per 10,000 person-years in females [33]. PAD has traditionally been reported to be a male-dominant disease [34]. However, PAD has recently been reported to affect women as much as men in the general population [34]. A systematic review reported that women had a slightly higher prevalence than men by the age of 75 years in high-income countries, measured by an arterial ankle brachial index (ABI) of 0.90 or less [6]. Classifying health care utilization by sex in this study revealed differences in claims between women and men. In terms of health care use, the number of tertiary hospital claims was high for men, whereas the number of clinic claims was high for women. In a Korean study, men accounted for a higher proportion than women of patients who received procedures at tertiary hospitals [35].

In our study, the PAD incidence trend among individuals in their 20s to 70s increased with age, which is similar to the findings of studies based in the United Kingdom [33] and United States [32]. Aging increases PAD-associated risk factors, such as hypertension, hyperlipidemia, and diabetes, and thereby increases the prevalence of PAD [2,36]. In terms of absolute change, patients with PAD in their 80s had the highest increase, at 1.10. Aging has increased the proportion of people in their 80s in the general population, and accordingly, the proportion of patients with PAD has also increased.

In our study, the prevalence of PAD was 3.93 and 23.55 per 1000 individuals in 2011 and 2018, respectively, indicating a steadily increasing trend, without decline. The prevalence of PAD has been reported to consistently increase [1,37]. In a study based on health insurance claims data in Germany, the number of prevalent cases of PAD consistently increased [24], which is similar to the findings of this study. In a meta-analysis, the prevalence of PAD was 5.56% in adults older than 25 years worldwide [6]. The results of this study are consistent with those of previous studies. Considering patients who do not visit hospitals due to having an asymptomatic condition, the incidence and prevalence of PAD may have been underestimated.

In this study, the number of EVR events fluctuated during the study period and increased from 933 in 2011 to 1206 in 2018. Similarly, an increasing trend in EVR events was reported for the US population from 1996 to 2011 among patients with PAD and diabetes [38]. PTA is recommended as the first-line revascularization intervention for PAD and is known to be effective, safe, and widely applicable, with few complications [13]; therefore, PTA has a positive effect on preventing major amputations [14], and the trend of PTA use has increased.

In our study, the rates of both major and minor amputations decreased slightly. The finding of a decreasing trend in major amputations over time is similar to the results of a study of patients with PAD based on health insurance claims data in Germany between 2008 and 2016 [24].

In this study, the numbers of patients who died in the hospital within 7 days and 30 days of a PAD diagnosis were 24 to 53 and 41 to 89, respectively, suggesting that a high proportion of in-hospital deaths occurred within 7 days. Patients with PAD may develop complications, such as ischemic myocardial and cerebrovascular events and sepsis [39-41], and older adults have a higher risk of complications than younger age groups [40]. Interventions and intensive monitoring of complications in the first month are necessary for hospitalized patients with PAD.

This study had some limitations. The data were claims data for health insurance that were collected through administrative processes and were not intended for research purposes. Furthermore, the previously entered diagnosis codes might not have been changed, or the doctor might have only entered the diagnosis and treatment codes that were required for the health insurance claims. Thus, the number of patients, procedures, or surgeries may have been underestimated. Furthermore, PAD was defined using disease codes only. Therefore, individuals who were not diagnosed with PAD but had CLI-associated symptoms and those with an ABI of less than 0.9 may have been excluded from the study, leading to underestimated results. As this was a retrospective study that was based on claims data, many potential confounders were not adjusted for in the analyses. Moreover, the use of descriptive statistics limits statistical inferences across study groups.

Therefore, it is necessary to carefully interpret our results on the incidence and prevalence of PAD; future studies that investigate this topic should adjust for confounders, such as risk factors, geographical heterogeneities, and medical disparities. Furthermore, we suggest that health outcomes, not only medical procedures and surgeries but also psychological well-being (eg, depression and anxiety) and quality of life, should be considered in association with PAD.

Our findings provide evidence for strategies for health promotion and intervention for patients with PAD and may help with strategies to manage risk factors, such as ceasing smoking, following a low-fat diet, and managing weight. The American Heart Association guidelines recommended walking as an exercise for controlling risk factors [15,42]. PAD causes pain when walking, which makes it difficult to carry out daily activities and can influence psychological health, such as by inducing depression and anxiety in patients with PAD. Therefore, the management of psychological health deserves attention in PAD care for aging populations.

In this study, increasing trends in incident cases and the prevalence of PAD in South Korea were observed between 2011 and 2018. PAD incidence was higher in women than men in this study. A strength of this study is that, methodologically, the epidemiological trends of the entire South Korean population and all patients with PAD in South Korea were ascertained through public data analysis. Furthermore, the health care utilization of patients with PAD was determined based on national data, which enables the generalization of results for the provision of information to undertake both prevention and treatment in the clinical setting and for further research.