1. Introduction
Ischemic heart disease is known as a representative disease with a high social burden that causes much death and disability [
1]. The prevalence of cardiovascular disease is rapidly increasing in women after the age of 40 due to changes in women’s hormones related to menopause, physical changes related to aging, and increased fat accumulation [
2]. Previous studies reported that women with risk factors for cardiovascular disease had a 19% increase in the incidence of myocardial infarction after 10 years and that the quality of life of middle-aged women with cardiovascular disease was poor [
3,
4]. The life expectancy of Korean women in 2015 was 85.2 years [
5], and the prevention and management of cardiovascular disease in middle-aged women are very important to prepare for a healthy old age. According to the 2017 Statistical Annual Report of Causes of Death in Korea, cardiovascular disease is the second-highest cause of death after cancer, and the mortality rate from cardiovascular disease also tends to increase sharply with increasing age. Particularly, hypertension disease (2.3 times) and heart disease (1.1 times) showed higher mortality rates among women than men [
6]. Cardiovascular disease is a major chronic disease. Chronic diseases have various causes but no direct cause, making early diagnosis difficult. In addition, the time of disease onset is unclear and the latent period is long [
7]. Therefore, since prevention is emphasized more than treatment in chronic diseases, if the characteristics of a group at high risk of cardiovascular disease can be identified and customized interventions suitable for each characteristic can be provided, the prevention and management of cardiovascular disease will be effective.
The risk factors for cardiovascular disease identified in previous studies included gender, age, marital status, income, education, diabetes, hypercholesterolemia, family history, smoking, drinking, obesity, lack of physical activity, and stress [
8,
9,
10,
11,
12,
13,
14,
15,
16,
17,
18,
19]. However, these studies investigated the incidence of cardiovascular disease related to a few factors by focusing on specific groups such as young men and the elderly as study subjects [
8,
9,
12,
13,
14,
15,
16,
18,
19]. Studies that have confirmed various characteristics in the groups vulnerable to cardiovascular disease are lacking. Therefore, to understand the characteristics of the groups vulnerable to ischemic heart disease, research using data mining techniques is required.
Data mining technology allows for the exploration, identification, and modeling of the relationships and rules that exist in big data [
20]. Recently, research methods using data mining have been used in various fields such as medical research, diagnosis, quality control, hospital management, and customer relationship management in the medical field [
21,
22,
23]. Decision tree analysis, one data mining technique, is an effective tool for classification and prediction; therefore, it is useful for discovering hidden patterns in data [
24]. Predicting cardiovascular disease risk using decision support systems can play an important role in disease prevention [
24].
In this study, we intended to analyze the factors related to ischemic heart disease in middle-aged women using the Korea National Health and Nutrition Examination Survey (KNHANES) data, which is representative of the Korean middle-aged and older women population, and develop an ischemic heart disease prediction model. The specific study purposes were as follows.
Identify the sociodemographic characteristics and health-related behavior characteristics of the study subjects.
Identify the differences in the prevalence of ischemic heart disease according to social demographic characteristics and health-related behaviors, and the presence of chronic diseases.
Identify the factors that affected ischemic heart disease in middle-aged women.
Utilizing data mining techniques, develop a predictive model for ischemic heart disease in middle-aged women.
The results of these studies can be used as important foundational data for regional and national health policy decisions for the prevention and management of ischemic heart disease.
4. Discussion
With the development of medical technology, life expectancy has increased, and women spend more than a third of their lives after middle age. The middle-aged period of women is the beginning period of before and just after the onset of menopause, and since health management after middle-age is closely related to the quality of life, active health management is necessary [
27]. Therefore, this study was performed to contribute to the prevention and management of ischemic heart disease for health promotion by identifying the factors related to ischemic heart disease in middle-aged and older Korean women and identifying the vulnerable group with a high prevalence of ischemic heart disease.
The prevalence of ischemic heart disease in the study was 2.77%, including those diagnosed with myocardial infarction or angina. It was slightly higher than the results of previous studies [
28], which suggested that about 1.72% of the world’s population is affected by ischemic heart disease. When the prevalence of ischemic heart disease was compared by age, it increased rapidly after 60 years old compared to those 40–49 years old. Previous studies have also shown that cardiovascular disease increased rapidly after 50 years old [
29,
30]. In particular, it is known that as women transition from middle age to old age, the incidence of cardiovascular disease increases due to changes in women hormones, physical changes according to aging, and an increase in body fat accumulation [
2,
27].
In this study, family history, hypertension, dyslipidemia, stroke, arthritis, and depression were found to be statistically significant as clinical factors affecting ischemic heart disease, and smoking, drinking, and physical activity were not related factors. Since the association was investigated in middle-aged and older women, the results differed from previous studies [
9,
11,
29,
31,
32] where smoking, drinking, and physical activity were associated with ischemic heart disease. Previous studies were conducted on both men and women with cardiovascular disease [
9] and on women in their 30s or older [
11], and it is thought that the results were different because they were more than the data set of cardiovascular disease patients used in this study. According to a previous study by Lim [
33] using machine learning, the major risk factors affecting the occurrence of myocardial infarction and angina were age, hypertension, dyslipidemia, family history, low educational background, and gender, consistent with the results of this study. The diseases identified as risk factors for cardiovascular in this study were hypertension, dyslipidemia, stroke, arthritis, and depression. However, since it is difficult to clearly identify a causal relationship in a cross-sectional study, it is also possible that individuals with ischemic heart disease may have had high prevalence of risk factors for comorbidities such as hypertension and dyslipidemia due to more frequent health care encounters and screening opportunities. Diabetes and renal failure did not show a statistically significant association. These results were similar to previous studies [
12,
14,
26,
34,
35] reporting that the cardiovascular disease risk factors depression and rheumatoid arthritis were significantly higher in women than men, and diabetes was statistically significantly higher in men. In a study by Seo et al. [
36], Korean adults with depression had a higher prevalence of cardiovascular disease than those without depression, and a previous study confirmed depression as a significant cardiovascular disease risk factor in women compared to men [
35]. Decreased renal function may increase the prevalence of cardiovascular disease and increase mortality [
37]. However, in this study, it was not a risk factor in middle-aged and older women.
As a result of the decision tree analysis to identify the groups vulnerable to ischemic heart disease, hypertension and family history were derived as the most relevant factors, consistent with the regression analysis. Focusing on hypertension, which is the biggest influencing factor, those who had hypertension, a family history, and were menopausal (16.67%), and those who had hypertension, no family history, and had a previous stroke (15.44%) were found to be the groups most vulnerable to ischemic heart disease. Taken together, the risk of ischemic heart disease increased in middle-aged and older women when combined with related factors such as hypertension, a family history of ischemic heart disease, menopause, and stroke. These results are consistent with the results of previous studies [
38,
39,
40] that postmenopausal women significantly increase the risk of cardiovascular disease.
The study results indicated that for the prevention and effective management of ischemic heart disease in middle-aged and older women, a customized program considering the characteristics of the subjects is intensively needed. The importance of women’s health care after middle age is emphasized, but in most cases, a uniform program is applied by integrating factors affecting cardiovascular disease [
7]. In previous studies [
8,
9,
10,
11,
12,
13,
14,
15,
16,
17,
18,
19], risk factors for ischemic heart disease were selected based on socioeconomic characteristics, some co-morbidities, and clinical test results. However, in this study, most of the comorbidities, socioeconomic characteristics, and lifestyle behaviors suggested to be related in previous studies were reflected and analyzed. In addition, there is a lack of previous studies that have identified factors affecting ischemic heart disease and risk groups in middle-aged women. According to the results of this study, family history, vascular disease, and depression appeared to be the biggest risk factors for cardiovascular disease in middle-aged women, rather than menopause and lifestyle, which can be seen as a different result from previous studies. Based on the results of this study, for the prevention and management of ischemic heart disease in middle-aged and older women, it is necessary to first classify the subjects according to the risk level of each vulnerable group. In addition, it is necessary to establish a customized prevention and management strategy according to the characteristics of the relevant factors in each vulnerable group. Utilization of healthcare big data can contribute to enormous cost savings in the healthcare field by providing patient-customized medical services based on data. E-health and m-health devices that combine technologies such as big data, data mining, and deep learning are bringing about innovation in the medical field, such as disease prevention, diagnosis, and treatment, by providing more effective and personalized solutions. If we add the function of identifying and managing high-risk and low-risk patients in advance using a predictive model to this technological system, we believe that it can contribute to the management of ischemic heart disease in middle-aged women. This study is significant in that it identified the characteristics of middle-aged and older women who are vulnerable to ischemic heart disease using large-scale data representing the entire Korean population. However, it had the following limitations. First, this study was cross-sectional, making the investigation of the cause–effect relationship between the risk factors for ischemic heart disease difficult. Second, there was a lack of data on clinical examinations related to ischemic heart disease. Third, since the ischemic heart disease variables used in this study were obtained as self-reported data on doctors’ diagnoses, there is a limitation that there may be a bias toward memory recall. In the future, it is necessary to analyze big data mining techniques in more depth with more data and conduct a prospective cohort study on the relationship between risk factors for ischemic heart disease by addressing the limitations of this study.
5. Conclusions
This study was conducted to identify ischemic heart disease-related factors and the vulnerable groups in Korean middle-aged and older women using data from the Korea National Health and Nutrition Examination Survey (KNHANES). The factors associated with ischemic heart disease in middle-aged and older women in this study were age, family history, hypertension, dyslipidemia, stroke, arthritis, and depression. Additionally, the group most vulnerable to ischemic heart disease were those with high blood pressure, a family history of ischemic heart disease, and menopause. It is meaningful that research to develop a predictive model for ischemic heart disease, with a high social burden of disease, using healthcare big data can be used as basic data to help in national policy decision-making for the prevention and management of chronic diseases. Based on these results, effective management should be achieved by applying customized medical services and health management services for each relevant factor in consideration of the characteristics of the groups with potential risk. In addition, it is necessary to reflect the realization of active screening programs and chronic disease management education programs that consider the comorbidity of patients with ischemic heart disease in health policies.