Background
Cardiovascular diseases (CVD) are the number one cause of mortality globally. In 2015, global estimated deaths caused by CVD were 17.7 million. More than three-quaters of these deaths occur in low- and middle-income countries [
1]. In Nepal, the estimated age-standardized death rates caused by CVD (Ischemic Heart Disease and Cerebrovascular Diseases) were 152 and 82 per 100,000 population respectively in 2008 [
2]. CVD were the second most common (40.0%) noncommunicable diseases among indoor patients of the non-specialist hospitals of Nepal in 2010 [
3]. Moreover, 13.8% of industrial workers of Nepal were diagnosed with CVD in 2016 [
4].
Based on attributable deaths globally, common CVD risk factors are high blood pressure (to which 13.0% of global deaths is attributed), tobacco use (9.0%), diabetes (6.0%), physical inactivity (6.0%), overweight/obesity (5.0%), cholesterol (4.5%), harmful use of alcohol (4.0%), and low fruit and vegetable intake (3.0%) [
2,
5,
6]. In Nepal, hypertension was the most prevalent risk factor for CVD which ranged from 26.0% to 38.9% [
7‐
11] during the last 3 years. Moreover, diabetes mellitus was seen in 8.4% of Nepalese population [
12]. STEPS survey of Nepal in 2013 detected hypercholesterol in 23.0%, smoking in 19.0%, overweight in 21.0%, raised blood glucose in 4.0%, physical inactivity in 3.0%, and harmful use of alcohol in 2.0% [
7]. These behavioral and metabolic risk factors usually cluster together, interact, and multiply so that the total risk of developing acute cardiovascular events is increased [
13,
14]. In Asia, for instance, almost 44.0% of Chinese adult population had clustered at least two cardiovascular risk factors [
15]. Moreover, in Nepal, more than 60.0% had a minimum of two clustered risk factors [
7]. Evidence shows that about 58.0% decline in CVD mortality has been attributed to reductions in the population levels of these risk factors [
16,
17].
A recent study from China reported that low-income areas had a higher prevalence of total CVD compared to high-income areas [
18]. In addition, cardiovascular health is poor in rural communities and disproportionally affects elderly populations [
19]. Risk factors and their clustering phenomenon should be explored to plan and organize individual and population-based interventions in rural communities focusing on elderly population. However, there is no data available on status and clustering of all cardiovascular risk factors in the elderly rural population in Nepal. Therefore, we aimed to determine the prevalence of CVD risk factors with a focus on their clustering in rural Nepalese population aged 40–80 years.
Discussion
This study determined the prevalence of cardiovascular disease risk factors along with their clustering phenomenon in a rural population of Nepal. Prevalence of each cardiovascular risk factor was high and a maximum of six risk factors was clustered in some study participants.
Our current study revealed that approximately one-quater (24.1%) were smoking cigarettes in a rural population of Nepal. Our finding was consistent with the tobacco smoking prevalence reported in other studies in Nepal. For instance, the proportion of current smoker was 29.0% in STEPS survey 2013 of Nepal among aged 40–69 years [
7] and 28.6% in rural Sindhuli [
31]. However, the prevalence of smoking found in our study was higher compared to that found in the capital city Kathmandu in urban settings (20.0%) [
10] and rural settings (21.7%) [
10,
32] and the sub-metropolitan city Pokhara (17.0%) [
8] of Nepal. In all of these studies, more males compared to females were smoking cigarettes. These studies revealed the severity of smoking in Nepal.
One in ten study participants was drinking a harmful dose of alcohol in the current study. Similar result was observed in a recent study conducted in Pokhara (12.0%) of Nepal [
8]. However, our finding was higher than the report of STEPs survey of 2013 (2.7%) for the 45 to 69 years of age group [
7]. Most of the current study subjects were of indigenous and Dalit caste. Such ethnic people were more likely to drink alcohol and brew alcohol at home [
33], which might be the reason for higher prevalence.
The burden of low fruit and vegetable intake was high in Nepal. The current study determined that about two-thirds (72.0%) were not consuming five servings of fruit and vegetable per day. This prevalence was lower when compared with the result of a study representing the whole country (99.0%) [
7] and a study from surveillance site in Bhaktapur (97.9%) of Nepal [
34]. Variation according to age, race/ethnicity, income, education, and availability of fruit and vegetable are established socio-demographic factors for low fruit and vegetable intake [
35,
36].
Ten percent of our study participants were engaged in a low level of physical activities. This prevalence was in line with the findings from Pokhara of Nepal (7.0%) and world health survey for physical activities (8.0%) [
8,
37]. However, current prevalence was less than the findings of capital city Kathmandu (40.2%) [
10], Eastern region (37.6%) [
38], and Bhaktapur (male: 18.0% and female: 22.0%) of Nepal [
39]. Work and travel related activities are the major domains for physical activities in Nepal [
39]. These domains are more pronounced in rural areas, and might be the reason for the lower prevalence of physical inactivity in our study.
About six in ten participants (59.0%) were overweight and obese in our study population. This prevalence was comparable with the result of Western Nepal (60.7%) [
38]. However, it was three-times greater than the findings of a stepwise survey of risk factors in Nepal (21.0%) [
7]. The higher prevalence of overweight and obesity may be related to the higher proportion of participants who smoke cigarette, chew tobacco, drink alcohol, and indulge in less physical activities in the current study population. Evidences support that alcohol energy intake may be responsible for weight gain if not counterbalanced, for instance, by physical activities [
40]. However, further studies would be needed to confirm and explain our findings.
Two-fifths of participants (43.0%) had hypertension in our study. The prevalence of hypertension in the current study (38.9%) was comparable with above-mentioned STEPS survey (47.0%) for the respective age of more than 45 years [
7]. However, hypertension was greater in our study compared to populations from Eastern Nepal (34.0%) [
38], municipalities of Kathmandu (32.5%) [
10], Pokhara-Lekhnath (28.0%) [
8], Dhulikhel (27.7%) [
9], and Surkhet (38.9%) [
11] of Nepal. Alcohol consumption, body mass index, total cholesterol, and triglyceride were correlated to systolic and diastolic blood pressure in our study. The high prevalence of these risk factors in our study might explain the higher rates of hypertension.
The prevalence of diabetes mellitus was 16.2% in our study. This prevalence was higher than the reported prevalences from Eastern Nepal for the age group 40 to 80 years (11.5%) [
38], STEPS survey 2013 (9.0%) for age group 45–69 years [
7], and rural population of Sunsari (9.0%) [
41]. One study conducted in Kathmandu valley reported that 25.9% of participants aged 60 years and older had diabetes mellitus [
42]. That means elderly age group has the higher chance of diabetes [
43]. A high proportion of diabetes in our study could be a result of the high prevalence of triglyceride that was correlated with fasting blood sugar. Another reason for a higher burden of diabetes in our study may be because of the use of an oral glucose tolerance test for those who did not have known diabetes.
Our study revealed more than half (56.0%) of participants of the rural population had dyslipidemia. This overall dyslipidemia was accounted by 17.0% of elevated total cholesterol, 27.0% of raised triglyceride, 30.0% decreased high-density lipoprotein, and 10.0% of raised low-density lipoprotein among all the study subjects. When compared with above-mentioned STEPS survey, our study population had less prevalence of dyslipidemia. For instance, among participants of age group 45 to 69 years of age, 33% had raised cholesterol, 35% had elevated triglyceride, and 24% had elevated low-density lipoprotein in the STEPS survey [
44]. Furthermore, the proportion of dyslipidemia in our study was less compared to another study from non-diabetes participants of the urban area of the capital city Kathmandu, which determined 73.3% had dyslipidemia [
45]. Our study revealed that prevalent risk factors namely waist circumference, systolic blood pressure, and fasting blood sugar were correlated with triglyceride level. Similarly, alcohol intake and fasting blood sugar were positively correlated with the reduction of serum high-density lipoprotein. All of these may have been responsible for such high prevalence of dyslipidemia.
Almost all of the study population had at least one risk factor. The finding of our study was consistent with the STEPS survey 2013 of Nepal which revealed 99.6% of participants had at least one risk factor [
7]. When compared with the studies from other Asian countries, clustering of at least two risk factors was observed in 44% of Chinese population [
15] and 76% of cases in Bangladesh [
46]. Comparably, the current study displayed 86% of study participants had a minimum of two risk factors clustered together. The current finding of clustering of three to five risk factors (63.4%) was higher compared to STEPS survey 2013 (30.0%) for the age group 45 to 69 years [
7]. Our study included the harmful use of alcohol, diabetes, and dyslipidemia when analyzing the clustering phenomenon, which the STEPS survey did not. This could explain the disparity between the findings.
When different risk factors act together, the effect will be multiplicative and raises the risk of CVD more than the summation of risk factors [
13,
14]. For instance, one study reported that incidence of ischemic heart disease rises from 0 to 40% as the number of risk factors conglomerate from zero to five among diabetic patients [
47]. Moreover, annual medical expenditure increases with the rise in clustering of risk factors [
48]. In our study greatest clustering was observed among 60–69 years of age group and Dalit participant. Therefore, it could be pronounced that preventive strategies should be focused on individuals who have more risk factors and especially elderly population who are aged 60–69 years and are Dalit.
It is important to emphasize health education programs that warn about the behavioral risk factors of CVD. In addition, early detection and treatment of intermediary risk factors (hypertension, diabetes, dyslipidemia and overweight) are required to minimize the future burden of CVD [
2]. Health promotion approaches could be delivered through various approaches: health workforce, trained community volunteers of the current health system, school health programs or media campaigns [
49‐
51] collaborating with all stakeholders. Such community-based programs have already been implemented in developed and developing countries [
50,
52]. Package of Essential Noncommunicable Disease (PEN) interventions could be implemented to prevent cardiovascular diseases as well, so that the community could utilize current health care delivery system [
53]. One study from Northern India revealed that the primary health care setting was a feasible setting for CVD risk management even in rural areas [
52].
Our study had several limitations. The study was conducted in a selected rural community where a large population of Janajati and women were residing. Our sample size was not large enough to make it a representative sample of all the risk factors. As we have included participants aged 40 to 80 years, we could not report the status of risk factor among the younger population. The current study might have underestimated the cardiovascular risk factors, as it excluded those who had known heart diseases, stroke, or intermittent claudication. The prevalence of risk factors might have been underestimated as about 11.0% of total participants did not involve in biochemical assessment, though socio-demographic characteristics of responders and non-responders were not significantly different. Despite these limitations, our study had several strengths. This is the first study conducted among elderly rural population of Nepal to explore all traditional risk factors of CVD including biochemical assessment. We used trained enumerators to acquire data related to the participants at their own home. We performed the oral glucose tolerance test to confirm diabetes along with the fasting blood sugar. Therefore, findings could be cautiously generalized to other population.
Acknowledgements
This paper is based on the thesis submitted to Bangladesh Institute of Health Sciences (BIHS) as a partial fulfillment of M.Phil degree in Noncommunicable Diseases under the University of Dhaka. The authors want to express their sincere gratitude and appreciation to Mr. Matthew Bourke, PhD student, Victoria University, Australia for copy editing of the manuscript. We really appreciate Prof. Liaquet Ali, Director of Bangladesh Institute of Health Science (BIHS) for his kind support and motivation during M.Phil and thesis period. We would thank Mr. Ramchandra Adhikari, Managing Director of Karmada Hospital Pt.Lt. for providing laboratory, logistics, managerial, and transportation facilities. We would like to appreciate and thank Laboratory Technician Mr. Bikash Siluwal for withdrawing and analyzing blood samples. We would like to thank Mr. Shailendra Pandit, Miss Pratiksha Adhikari, Miss Yem Kumari Gurung, Dr. Anil Koju, Dr. Krishna Malakar, Mr. Dwarika Mishra, Janaklal Shreshtha, and secretaries of Bhowtewodar and Sundarbazar VDC who played the key role in community mobilization, data collection, and data management. Finally, we would like to acknowledge the study team and study participants.