Prevalence of Cardiovascular Risk Factors

Hypertension and obesity are established and independent risk factors for cardiovascular diseases. There are important inter-relationships between these two factors that may explain the aetiology of coronary heart disease. To determine the prevalence of hypertension and obesity in a rural community setting in Malaysia, and to identify their associated factors, a cross-sectional study was conducted among residents aged 15 years and above in Mukim Dengkil, Selangor from June to October 1999. Sample size was 570, giving a response rate of 86.7%. Prevalence of hypertension was 26.8%, with the highest prevalence among those aged 60 years and above (57.3%), and 50 to 59 years old (53.3%). Factors found to be significantly associated with hypertension were male (χ2=4.71, df=1, p<0.05) and age (t=10.7, df=568, p<0.01). Prevalence of obesity was 11.4%, with the highest prevalence among those aged 40 to 49 years (22.7%) and 30 to 39 years (14.4%). The factors associated with obesity were age (p<0.01), female (χ2=12.45, df=1, p<0.05) and ethnicity (Fisher’s Exact probability, p<0.05) with Chinese and Malays having a higher prevalence compared to other ethnic groups. However, there was no significant association between hypertension and obesity (OR=1.14, 95% CI=0.65, 2.02). The prevalence of hypertension and obesity in this study is high. There is a need for prevention programs for these risk factors in rural communities in Malaysia. INTRODUCTION Cardiovascular diseases (CVD) are important causes of worldwide preventable morbidity and mortality (Ahmad, 1995; Hennekens, 1998). Many studies have found that two major manifestations of CVD are coronary heart disease (CHD) and stroke (Khoo, Tan & Liew, 1997; Khoo, Tan & Khoo, 1991; Jonas et al., 1992; Teo, Chong & Abdul Rahman, 1998). CHD is by far the major contributor to the overall mortality (Cooper & Schatzkin, 1982). CVD are expected to become a major concern in developing countries (Tatsanavivat et al., 1998). Since the early 1970s, CVD have been the major cause of mortality in Malaysia (Khoo et al., 1997; Khoo, 1996; Khor et al., 1997), with the mortality rates due to CHD still on the rise (Khoo et al., 1991). Based on the increasing mortality rates, Malaysia is facing a major CHD epidemic (Yusoff, 1996). The most established and independent risk factors of CVD in adults are hypertension and obesity (Hughes et al., 1993; Semenciw et al., 1987; Kanemoto & Hirose, 1988). These factors as well Correspondence author: Dr. M.S. Sherina, e-mail: [email protected] A. Mohd Yunus, M.S. Sherina, M.Z. Nor Afiah, L. Rampal & K.H. Tiew as others such as smoking, diabetes mellitus, stress and diet are known modifiable risk factors, whereas age, male sex and positive family history are non-modifiable risk factors. A combination of risk factors has been shown to increase the risk as well as subsequent occurrence of CVD (Wood et al., 1998). Hypertension is a silent disease. Numerous hypertensive cases are not detected due to a simple lack of routine check-up (WHO MONICA Project, 1989). In addition, the onset of hypertension is insidious and there is an absence of overt symptoms in its early stages (Rimm, Stampfer & Giovannuci, 1995). However, it is a significant and independent risk factor for CHD morbidity and mortality, regardless of age, gender, ethnicity and history of CHD (Gensini, Comeglio & Colella, 1998). Hypertension may also potentially interact with other risk factors to speed up CHD development (Ministry of Health, 1998). The prevalence of hypertension in Malaysia is between 14.0 to 24.1% (Ministry of Health, 1999). It contributes to more than one-third of premature mortality due to CHD and a greater proportion due to stroke (Ministry of Health, 1999; NHMS2, 1997). It is also an important risk factor for premature mortality in heart and kidney failures (Ministry of Health, 1999). Obesity is mainly due to a reduction in spontaneous and work-related physical activity, and excessive consumption of foods with high fat content or rich in energy (Wood et al., 1998). Being obese is defined as having a body mass index (BMI) value of 30.0 kg/m2 or more that may be hazardous to health (WHO MONICA Project, 1989). BMI, waist-to-hip ratio, short stature and gaining of weight starting at the age of 21 are related to an elevated risk of CHD (Rimm et al., 1995). Obesity is closely associated with its biologic effects such as hypertension, diabetes mellitus, hypercholesterolaemia and this association is responsible for an increase in CVD and all-cause mortality (Gensini et al., 1998). The identification and public intervention of hypertension and obesity are important to reduce the morbidity and mortality rates of CVD. In Malaysia, many studies have been done on CVD risk factors in hospital settings; however there is inadequate published data on CVD risk factors in the community, mainly rural communities. The objective of this study was to determine the prevalence of hypertension and obesity in a rural community setting in Malaysia. METHODOLOGY The Malaysian community is divided into rural or urban settings. A rural community can be further divided into small towns and villages depending on the size of the population. This study was conducted in the rural community of Mukim Dengkil, which covers an area of 29,400 hectares and consists of 25 villages and a population of 15,414. This was a cross-sectional study using stratified proportionate systematic random sampling. Five villages were randomly selected. Of the 530 households in the 5 villages, 300 households were selected via proportionate sampling. All residents aged 15 years and above in the selected households were interviewed. Those who refused to participate were excluded from the study. Prevalence of Cardiovascular Risk Factors in a Rural Community in Mukim Dengkil, Selangor After obtaining verbal consent, respondents were personally interviewed by one of the authors using a pre-tested and structured questionnaire. The questionnaire included questions on sociodemographic factors (age, gender, ethnicity) and history of self-reported diagnosed hypertension. For respondents who reported themselves as having hypertension, blood pressure measurements were also taken using an Accoson’s mercury sphygmomanometer. The Malaysian Hypertension Consensus Guidelines (Ministry of Health, 1998) on measuring blood pressure was used. The average of two blood pressure measurements was used in the statistical analysis. The measurements of height and body weight were done with the respondents standing in light garments and barefoot. Height was measured using a seca body meter which was suspended upright against a straight wall. The person to be measured stood underneath the bodymeter before the measuring beam was pushed down to rest on top of the head of the person. The visual display showed the person’s height and this was recorded to the nearest tenth of a centimeter. Body weight was measured using a seca weighing scale with an accuracy of 0.5 kilogram (kg). Body Mass Index (BMI) was calculated as weight in kg divided by height in meter squared (m2). BMI (kg/m2) is used to determine obesity based on the classification by the Ministry of Health (1999) as shown below. Table 1. Classification of Body Mass Index (BMI) by the Ministry of Health (1999)