Prevalence and Distribution of Cardiovascular Risk Factors in An Urban Industrial Population in South India: A Cross- Sectional Study

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1 Original Article Prevalence and Distribution of Cardiovascular Risk Factors in An Urban Industrial Population in South India: A Cross- Sectional Study P Kaur*, TV Rao*, S Sankarasubbaiyan**, AM Narayanan***, R Ezhil*, Sudha Ramachandra Rao*, MD Gupte* Abstract Background : Cardiovascular diseases (CVD) are leading cause of death in developing countries including India. The huge burden of CVD in Indian subcontinent is the consequence of the large population and high prevalence of cardiovascular risk factors. This study was done to determine the prevalence of cardiovascular risk factors in two industrial units in Chennai, India. Methods : Survey of behavioural risk factors using structured questionnaires and anthropometric measurements were done for the study population. Blood samples were collected for the fasting plasma glucose and serum cholesterol. Trend chi-square was employed to test the linear trend. Results : The total study population included 2262 male subjects. Blood samples were collected for 2148 (95.0%) subjects. Age range was years. Prevalence of major cardiovascular risk factors was: current smokers 462 (20.2%), body mass index 23 kg/m (66.8%), central obesity 1589 (70.2%), hypertension 615 (27.2%), diabetes mellitus 350(16.3%) and total cholesterol 200mg/dl in 650(30.3%). Conclusions : The study results indicated high prevalence of behavioural risk factors, central obesity, hypertension and diabetes in a select group of middle and high-income young urban males. The long-term follow-up in such settings will provide an opportunity to understand the influence of risk factors on cardiovascular disease outcomes. Cardiovascular diseases are leading cause of death in developing countries accounting for 17% of the total deaths. 1 Developing countries contributed 63% to the global mortality due to cardiovascular diseases (CVD) in India contributed 17% to the global mortality due to CVD. 2 In India, CVD account for 31.7% of the deaths. Deaths from coronary heart disease rose from 1.17 million in 1990 to 1.59 million in 2000 and are expected to rise to 2.03 million in In addition to high CHD mortality in Indian subcontinent, it manifests almost 10 year earlier on average in this region compared with the rest of the world, resulting in a substantial number of CHD deaths occurring in the working age-group. 4,5 The huge burden of CVD in Indian subcontinent is the Introduction consequence of the large population and high prevalence of cardiovascular risk factors. 6 These risk factors include smoking, alcohol, lower fruit and vegetable intake, physical inactivity, obesity, high blood pressure, raised blood glucose and abnormal blood lipids. 7 Recently, there were reports of high prevalence of these cardiovascular risk factors among industrial populations in various parts of India. Industrial units have captive population and therefore provide an opportunity to establish sentinel surveillance for cardiovascular risk factors. 8,9 In addition, as many of the industrial units in organized sector have their own primary health care facilities, it provides an opportunity for routine screening and follow-up. Therefore, we selected an industrial population in south India to determine the prevalence of cardiovascular risk factors. *National Institute of Epidemiology (Indian Council of Medical research), Plot R-127, 3 rd Avenue, Ambattur Housing Board, Phase I and II, Chennai , India. **Sundaram Medical Foundation Dr. Rangarajan Memorial Hospital, Shanthi Colony, 4 th avenue, Anna Nagar West, Chennai , India. ***ARMA Clinical Services and Hospitals Private Ltd, 73 and 77, First main road, Gandhi nagar, Adyar, Chennai , India. Received : ; Accepted : Methods Study design and setting Chennai, Tamil Nadu is the fourth largest metropolitan city in India with a population of 4.3 million. We conducted cross-sectional study in two industrial units in Chennai between Aug 2003 and Dec Industrial units were selected based on the feasibility of long-term follow- up of JAPI VOL. 55 NOVEMBER

2 the cohort with limited resources. Each unit had nearly 1200 employees with an in-house functional medical center that keeps medical records. The World Health Organization (WHO) step-wise approach was used to determine the prevalence of cardiovascular risk factors in the study population. 7 The three components of the study were (1) questionnaire based survey for behavioral risk factors, (2) anthropometric measurements and (3) biochemical measurements. Institutional ethics committee of the National Institute of Epidemiology, Chennai approved the study. Free and informed consent was obtained for the questionnaire based interview and laboratory tests. We referred newly detected patients with hypertension, diabetes, and dyslipidemias to the in house physician for further management. Data on socio-economic status, tobacco consumption, alcohol consumption, physical activity, diet, anthropometric measurements and blood pressure was collected from all the study subjects. Blood samples for biochemical measurements were collected from subjects who consented for blood sample collection. Questionnaire for demographic and behavioural risk factors We used questionnaire to collect data on demographic and behavioral risk factors. Tobacco questionnaire included data on self reported duration, frequency and quantity of tobacco consumption. Individuals were classified as ex-smoker, current smoker and smokeless tobacco product consumer. Self reported alcohol intake data was collected and subjects were classified as present consumer, past consumer and not a consumer. A physical activity questionnaire, validated for urban middle class Indians, was used. 10 Individuals were classified based on physical activity level that is composite index of physical activity patterns. Data on fruit and vegetable intake was collected. Anthropometric measurements Weight was measured in the upright position to the nearest 0.1 kg using calibrated balance beam scale. Height was measured without shoes to the nearest 0.1 cm using calibrated stadiometer. Body mass index (BMI) was calculated by dividing observed weight by height squared (kg/m 2 ). Waist circumference (WC) was measured to the nearest 0.1 cm at the narrowest point between lower end of the rib cage and iliac crest. Hip circumference was measured to the nearest 0.1 cm at the greatest horizontal circumference below the iliac crest at the level of greater trochanter. Blood pressure was measured from the right arm after the subject had been sitting for at least five minutes using digital automatic blood pressure apparatus (Omron MX3). The average of the two readings taken five minutes apart was recorded. Biochemical measurements Five ml of blood was collected from ante-cubital vein in two test tubes after 10-hour overnight fasting period. Blood sample for plasma glucose was collected in the test tube containing haparin sodium fluoride. Plasma glucose and total cholesterol were measured using an autoanalyser. The glucose oxidase- peroxidase method and cholesterol oxidase-cholesterol peroxidase method were used for measuring plasma glucose and serum cholesterol respectively. Definitions Current smoker: A person who had smoked at least 100 cigarettes over their lifetime, and continued to smoke every day or some days. Ex-smoker or former smoker was defined as a person who had smoked more than 100 cigarettes over their lifetime and who did not smoke every day or some days. 11 Alcohol use: Present consumer was defined as person who continued to consume alcohol everyday or some days. Past consumer was defined as person who was consuming alcohol in the past and stopped taking alcohol. Physical activity level (PAL): It calculated as: 24 hour energy expenditure /basal metabolic rate. Cut-offs for physical activity level describe grades of physical activity. These cut-offs are <1.4 = sedentary, = moderately active and > 1.75=heavily active. 12 BMI classification: Subjects were classified using WHO classification and classification recently recommended for Asians. 12,13 Central obesity was defined as either WC>=90 cm 13 or Waist-Hip Ratio (WHR)>0.90 for men. 14 Hypertension: Defined as systolic blood pressure (SBP) of 140 mmhg or diastolic blood pressure (DBP) 90 mmhg as per WHO criteria 15 or history of previously known disease and pre-hypertension was defined as SBP mmhg or DBP mmhg. Type 2 Diabetes mellitus: Diagnosed either by history of previously known disease or fasting plasma glucose of 126mg/dl and impaired fasting glucose was defined as fasting plasma glucose mg/dl. 16 Hypercholesterolemia: Defined as total cholesterol level 200 mg% according to USA - adult treatment panel (ATP) III guidelines. 17 Data collection and Statistical analysis Trained field investigators using structured standardized instruments collected the data and 5% random checks were done on the collected data under the supervision of senior medical officers. Data was coded and double entered in the computer for analyses. Linear trend was evaluated in various age groups, BMI categories and WHR categories by trend chi-square. Statistical package SPSS (version13.0) was used for the analyses. All analyses were two-tailed and P-value < 0.05 was considered statistically significant. Results Study population included 2262 males aged years. The blood samples were collected for 2148 (95.0%) subjects. Mean age was 40.6 ±11.2 years. Among 2262 subjects, 1468 (65%) were above 35 years of age. Nearly JAPI VOL. 55 NOVEMBER 2007

3 half [1029(45.5%)] had graduate or post-graduate level education, 1070(47.3%) had secondary and 163 (7.2%) had primary school education respectively. Median family income was Rs per month. Family size was less than five for 1425(63%) of the subjects. Mean and Standard Deviation (SD) of various risk factors is given in Table 1. Prevalence of cardiovascular risk factors is given in Table 2.Tobacco consumption was prevalent in 753(33.3%) subjects. About one third of the study subjects were current alcohol consumers. Based on the physical activity levels (PAL), 243(10.7%) were sedentary and 675 (29.8%) had heavy physical activity level. Median fruit and vegetable intake was 3.3 serving/day. Prevalence of overweight (BMI 25.0 kg/m kg/m 2 ) and obesity (BMI 30.0 kg/m 2 ) using WHO definition was 36.3% and 6.9% respectively. As per WHO recommendations for defining risk thresholds among Asians, 47.1% were in increased risk (BMI 23.0 kg/m kg/m 2 ) and 19.6% were in high-risk (BMI 27.5 kg/m 2 ) category. Central obesity using WHR criteria (>0.90) and WC criteria ( 90cm) was present in 1589(70.2%) and 1134(50.1%) subjects. Pre-hypertension and hypertension were prevalent in 901(39.8%) and 615(27.2%) subjects respectively. Among the hypertensives, 388(63%) were newly detected. Among known hypertensives, 110 (48.5%) had blood pressure under control (SBP <140 mmhg and DBP<90 mmhg). Prevalence of impaired fasting glucose and diabetes mellitus was 346 (16.1%) and 350(16.3%) respectively. Among the diabetics, 73(20.8%) were newly detected. Among known diabetics, 146 (52.7%) had blood glucose under control (<126 mg/dl). One-third of the subjects had raised total cholesterol. Age specific prevalence of various risk factors is given in Table 3. There was significant increase in prevalence of current smoking, high risk BMI, central obesity, hypertension, diabetes, hypercholesterolemia with increasing age ( p<0.001). There was sharp increase in prevalence of smoking and high-risk BMI above the age of 25 years and reached a plateau after 44 years. Prevalence of central obesity and diabetes increased up to 54 years and plateaued thereafter. Prevalence of hypertension continued to increase across Table 1 : Mean and standard deviation (SD) for various cardiovascular disease risk factors in the study population in industrial units, Chennai, India, (N=2262) Variables Mean SD Age (years) Height (cm) Weight (kg) Body mass index (kg/m 2 ) Waist circumference (cm) Hip circumference (cm) Waist /hip ratio Systolic blood pressure (mmhg) Diastolic blood pressure (mmhg) Fasting blood glucose (mg/dl) Total cholesterol (mg/dl) Table 2 : Prevalence of cardiovascular disease risk factors in the study population in industrial units, Chennai, India, (N=2262) Variables No. % Tobacco use Current smokers Ex. smokers Only smokeless tobacco products Alcohol consumption Present consumer Past consumer Physical activity levels (PAL) > Physical measurements Body mass index-who classification (kg/m 2 ) < Body mass index-classification recommended for Asians (kg/m 2 ) < Central obesity Waist circumference >= 90.0cm Waist-hip ratio > Hypertension Pre hypertension Hypertension self reported Hypertension newly detected Biochemical measurements (N=2148) Impaired fasting glucose Diabetes mellitus self reported Diabetes mellitus newly detected Hypercholesterolemia ( 200mg/dl) the age groups. Figure 1 shows the proportion of male subjects with hypertension and diabetes across the BMI range. Prevalence of hypertension and diabetes increased across the BMI range and the linear trend was statistically significant (p < ). Figure 2 shows the prevalence of hypertension and diabetes across WHR range. Prevalence of both the diseases increased across WHR range and the linear trend was statistically significant (p<0.0001). The prevalence of hypertension began to increase at BMI of kg/m 2 and WHR of The prevalence of diabetes started increasing at WHR of Figure 3 shows the prevalence of hypertension and diabetes in three categories of physical activity levels (PAL). Prevalence of both hypertension and diabetes was highest in sedentary PAL category and lowest in heavy PAL category (p <0.05). Discussion JAPI VOL. 55 NOVEMBER

4 Table 3 : Age-specific prevalence of cardiovascular disease risk factors in the study population in industrial units, Chennai, India, (N=2262) Age Group (years) No. % No. % No. % No. % No. % Total no. of subjects No. of subjects with lab parameters Current smokers Body mass index ( 23.0 kg/m 2 ) Central obesity (Waist hip ratio >0.90) Hypertension Diabetes mellitus Hypercholesterolemia ( 200mg/dl) Fig. 1 : Proportion of study subjects with hypertension and diabetes across body mass index range. (N = 2262 for hypertension and N = 2148 for diabetes). Fig. 3 : Proportion of study subjects with hypertension and diabetes by physical activity level (N = 2262 for hypertension and N = 2148 for diabetes). Fig. 2 : Proportion of study subjects with hypertension and diabetes across waist-hip ratio range. (N = 2262 for hypertension and N = 2148 for diabetes). Our study results indicated high prevalence of behavioral risk factors, central obesity, hypertension and diabetes among middle and high-income young males in an urban industrial population in South India. Prevalence of these risk factors increased during the most productive years (25-44 yrs) putting them at risk of cardiovascular morbidity and mortality at relatively younger age. This population provided an opportunity to study the influence of socioeconomic and lifestyle transition on the prevalence of cardiovascular risk factors. Our results were consistent with the multicentric study done in industrial settings in India. 8 Among behavioral risk factors, contrary to recent community based studies; we observed lower prevalence of sedentary physical activity level. 18 This was due to the type of work profile of the factories where the study was carried out. These are manufacturing sector factories and type of work done by majority of the employees was moderate to heavy in nature. Though sedentary subjects formed small proportion, they had higher prevalence of hypertension and diabetes as compared to other categories. We observed lower fruit and vegetable intake than recommended. In our study; majority of the employees had two meals per day in the campus canteen that served vegetarian meals. Canteen food had high proportion of carbohydrates and relatively lower proportion of fruits and vegetables. Goyal A et al in a recent paper reported lower intake of vegetables and fruits among south Asians as compared to other ethnic groups based on Interheart study data. 6 They also emphasized that vegetarianism in Indians does not necessarily mean adequate intake of fruits and vegetables. We need to improve awareness among Indians to increase fruit and vegetable intake. Mean BMI and prevalence of overweight, high-risk BMI and central obesity in our population was higher as compared to other industrial settings. 8,9 This could be due to better socio-economic status and more urbanized study population. High prevalence of hypertension and diabetes in JAPI VOL. 55 NOVEMBER 2007

5 our study was consistent with the recent Indian studies. 8,9,18 Contrary to other industrial population, we observed high awareness of diabetes. 9 This could be due to a diabetes screening camp that was organized in one of the industrial units prior to the study. However, consistent with other industrial study, awareness and control of hypertension was low. Hypertension remains undetected and uncontrolled even in organized sector industries with medical facilities. Hence, educating physicians in these settings and health education among employees can improve early detection and management. We observed prevalence of hypertension and diabetes increased with increasing BMI and WHR. The prevalence started increasing at much lower BMIs and WHR than recommended risk thresholds for western population. Similar observation was made in another study done in an industrial setting in northern India. 9 Ramachandran et al in a study from Chennai observed increasing trend of diabetes at lower BMI, WC and WHR. 19 Deshmukh et al observed hypertension in rural Indian population at lower BMI, WC and WHR. 20 Several other studies done in Asians observed higher susceptibility to cardiovascular risk factors at lower BMIs. Based on these findings, WHO expert consultation had revised BMI cut-offs for Asians. 13 Our results support the use of revised lower cut-offs of BMI for Asian Indians for identifying high-risk group and for initiating interventions. Prabhakar et al observed the high prevalence of cardiovascular risk factors in industrial settings in northern India and expressed it as cause of concern as well as an opportunity for carrying out work place prevention programs. 9 Our results reinforce the need for low-cost workplace intervention programs. We made recommendations to the management of the factory that included implementation of strict no smoking policy inside the campus, smoking cessation clinic, health education programme to increase awareness about healthy lifestyle, modification of the canteen meal menu and to motivate sedentary employees to participate in sports and other physical fitness programmes. In addition, we recommended periodic follow-up of the employees with hypertension and diabetes using target oriented protocol based approach in the in-house clinic. The management of the factory has started implementation of these interventions with the assistance of our institution. The results of the study cannot be generalised to the general urban population as the study was done in an industrial population that had higher socio-economic status and unique work profile. In addition, study population essentially consisted of males. The strength of our study was comprehensive survey of risk factors using WHO stepwise approach and in depth study of life style related risk factors using standardized tools. In addition, we shall assess the feasibility of implementing interventions and assessing the impact of interventions in an industrial setting. Conclusions The young adult population in select urban industrial environment in India have high prevalence of cardiovascular risk factors that can put them at the risk of increased cardiovascular morbidity and mortality at relatively young age. The long-term follow-up in such settings will provide an opportunity to understand the influence of risk factors on cardiovascular disease outcomes. Acknowledgements We thank Dr. V Seshadri, Dr MK Mani, Dr S Sivashanmugam and management of the factory for their cooperation and support, Prof K. Ramachandran for assistance in designing the study and Mr. Paul Tamby for data management. 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6 16. American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care 2004; Suppl 1: S5-S Expert panel on Detection, evaluation and treatment of high blood cholesterol in adults. Executive summary of the third report of the National Cholesterol Education Programme (NCEP) expert panel on detection, evaluation and treatment of high blood cholesterol in adults(adult Treatment Panel III). JAMA 2001;285: Gupta R, Gupta VP, Sarna M, Bhatnagar S, Thanvi J, Sharma V et al. Prevalence of coronary heart disease and risk factors in an urban Indian population Jaipur Heart Watch-2. Indian Heart J 2002;54(1): Snehalatha C, Viswanathan V, Ramachandran A. Cutoff values for normal anthropometric variables in Asian Indian adults. Diabetes Care 2003;26: Deshmukh PR, Gupta SS, Dongre AR, Bharambe MS, Maliye C, Kaur S, et al. Relationship of anthropometric indicators with blood pressure levels in rural Wardha. Indian J Med Res 2006;123: Announcement 7 th International Symposium on Diabetes Venue: Mumbai Date: 5 th & 6 th January 2008 Theme : Master Class in Diabetes and its Therapeutic Intervention Course Directors: Prof. K. Sreekumaran Nair, David Murdock Dole Professor and Professor of Medicine, Division of Endocrinology, Mayo Clinic, 200 First Street S.W. Rochester, MN USA. CME credits will be awarded For further details contact: Dr. Shashank R Joshi, Organising Secretary, Joshi Clinic, 12, Golden Palace, Turner Road, Bandra (W), Mumbai Tel: ; Fax: srjoshi@vsnl.com Advance Registration: Rs. 5000/- Before 30th November 2007 Reserve early as we have limited Registrations The Demand Draft should be in favour of Mayo IID Update payable at Mumbai JAPI VOL. 55 NOVEMBER 2007