PRABHAKARANTHE NATIONAL MEDICALet al. : CARDIOVASCULARJOURNAL OF RISK BURDEN VOL. 18, INNO AN. 2 INDIAN, 2005 INDUSTRY 59 Original Articles

Cardiovascular risk factor prevalence among men in a large industry of northern India

D. PRABHAKARAN, PANKAJ SHAH, VIVEK CHATURVEDI, LAKSHMY RAMAKRISHNAN, AJAY MANHAPRA, . SRINATH REDDY

ABSTRACT metabolic syndrome was present in 28%–35% of the individu- Background. Industrial settings, with their intramural re- als depending on the diagnostic criteria used. The prevalence of sources and healthcare infrastructure, are ideal for initiating several risk factors and the metabolic syndrome was high with preventive activities to increase the awareness and control of increasing age, BMI and waist circumference. A third of those cardiovascular diseases (CVD). However, there are no reliable who had hypertension (31.5%) and diabetes (31%) were aware estimates of CVD and risk factor burden, nor of its awareness and of their status. Among those aware, adequate control of blood treatment status in urban Indian industrial settings. We aimed to pressure and blood glucose was present in only 38% of those evaluate the prevalence of CVD and its risk factors, and to assess with hypertension and 31% of those with diabetes, respectively. the status of awareness and control of CVD risk factors among Coronary heart disease was present in 7.3% of the individuals a large industrial population of northern India. while 0.3% had a history of stroke. Methods. We conducted a cross-sectional survey among all Conclusion. This study demonstrates the high prevalence of employees aged 20–59 years of a large industry near Delhi CVD and its risk factors against a background of poor awareness (n=2935), to evaluate their cardiovascular risk profile—by and control among a comparatively young male population in a employing a structured questionnaire and clinical and biochemi- north Indian industrial setting. cal estimations. The presence of coronary heart disease was Natl Med J India 2005;18:59–65 ascertained by evidence of its treatment, Rose angina question- naire and Minnesota coded electrocardiograms. INTRODUCTION Results. The results for 2122 men, in whom complete The cardiovascular disease (CVD) burden of India is expected to information was available, are reported here. The mean age was double in the next two decades, making it the single largest cause 42 years and 90% of the men were below 50 years of age. The of death and the second largest cause of disability by the year prevalence of major CVD risk factors (95% CI) was: hyperten- 2020.1 This will be characterized by an enormous burden of CVD sion 30% (28%–32%), diabetes 15% (14%–17%), high among urban communities. Further, the prevalence of CVD in serum total cholesterol/HDL ratio (>4.5) 62% (60%–64%) rural and semi-urban areas is expected to increase substantially.2,3 and current smoking 36% (34%–38%). Forty-seven per cent While the exact aetiology of this predisposition to CVD in Indians of the respondents had at least two of these risk factors. Another is still debated, from a public health point of view it is clear that 44% (95% CI: 42%–46%) had pre-hypertension (JNC VII the rapid transition in diet and lifestyles with urbanization has criteria) and 37% (95% CI: 35%–39%) had evidence of either contributed to increasing levels of potentially reversible CVD risk impaired fasting glucose or impaired glucose tolerance. Thirty- factors.4 Data from several cross-sectional studies confirm the five per cent (95% CI: 33%–37%) of the individuals were high prevalence of risk factors such as smoking, type 2 diabetes, 5–11 overweight (BMI >25 kg/m2) while 43% (95% CI: 40%– high blood pressure, dyslipidaemia and obesity in urban Indi- 45%) had central obesity (waist circumference >90 cm). The ans. Despite this high burden, there is poor awareness among Indians, in addition to low detection and control rates.12–18 The Cardiothoracic Sciences Centre, All India Institute of Medical Sciences, reasons for this include low literacy, lack of access to healthcare Ansari Nagar, New Delhi 110029, India and competing priorities such as infectious and nutritional dis- D. PRABHAKARAN, LAKSHMY RAMAKRISHNAN, eases. Given this background and with the expected overall K. SRINATH REDDY Department of Cardiology improvement in literacy and socioeconomic status, it would be Department of Internal Medicine, Mayo Clinic, Rochester, USA useful to study the awareness of CVD risk factors and lifestyle PANKAJ SHAH Division of Endocrinology patterns in industrial settings, where the access to healthcare is Initiative for Cardiovascular Health Research in Developing Countries, usually better than that among the general community. New Delhi, India VIVEK CHATURVEDI Recent research has highlighted the importance of a continuum 19–23 Initiative for Cardiovascular Health Research in Developing Countries, of risk with variables such as blood pressure and glucose. New Delhi, India and Division of Hospital Medicine, Hackley Hospital, There is robust evidence of increased vascular risk even in the Muskegon, Michigan, USA presence of pre-hypertension (or high-normal blood pressure) and AJAY MANHAPRA pre-diabetes (impaired fasting glucose and impaired glucose Correspondence to K. SRINATH REDDY; [email protected] tolerance).24,25 These risk categories have a high rate of progres- © The National Medical Journal of India 2005

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sion to hypertension and type 2 diabetes. They are also compo- centre of these two points was marked. At this point the waist nents of the metabolic syndrome, which confers an almost 2-fold circumference was measured with a fibreglass tape after apply- risk for future diabetes, CVD mortality and morbidity.26,27 How- ing a tension of 600 g (done with the help of a spring balance). ever, detailed data regarding the burden of these risk factors in The measurement was made up to the nearest millimetre. Ad- India are limited. equate care was taken to ensure that the subject was breathing We report the findings of a survey done among the employees normally at the time the measurement was taken. Hip circumfer- of a large organized sector industry located close to Delhi. The ence was measured at the level of the greater trochanters with the main objectives of the study were (i) to study the risk factor and subject standing and breathing normally in a manner similar to treatment status in individuals with respect to CVD, (ii) to that during measurement of the waist circumference. All the estimate the prevalence of risk factors for coronary heart disease measurements were taken without intervening clothes, with the (CHD), both traditional and intermediary, and (iii) to estimate the subject wearing a loose-fitting surgical gown. prevalence of CHD using a history of previously diagnosed An ECG was obtained after the clinical measurements. All disease, Rose angina questionnaire and electrocardiogram (ECG). ECGs were read by a cardiologist and coded using the Minnesota coding system. Ten per cent of randomly selected ECGs were METHODS checked by two different cardiologists for agreement. There was Study design and setting complete agreement between the original and fresh coding. We did a cross-sectional survey of all employees in the 20–59 (Kappa was not estimated in view of the complete agreement.) years’ age group in an organized sector industry, during 1995–98. A total of 2935 employees (344 women and 2591 men) were Laboratory measurements eligible to participate. All potential participants received a letter Blood samples were drawn by trained personnel, centrifuged inviting them to participate in the study. Approval for conducting and stored for later analysis. Laboratory measurements included the study was obtained both from the management and the estimation of fasting blood glucose, 2-hour post-load blood employee representatives. Participation in the study was voluntary glucose (all post-load measurements were made 2 hours after a and all the measurements were carried out in the medical unit 75 g glucose solution was administered orally under supervi- located within the industry. Informed consent was obtained from sion), plasma insulin (both fasting and post-load), total blood each participant. cholesterol, high density lipoprotein (HDL) cholesterol (HDL- C), and triglycerides (both fasting and post-load). Glucose was Study questionnaire analysed by the glucose oxidase method (GOD-PAP), choles- We used a simple structured questionnaire which was adminis- terol by the CHOD-PAP method, and triglycerides were esti- tered by research assistants, who had received training in the mated by the GPOD-PAP method. The intra- and interassay methodology of field-based cardiovascular surveys. The question- coefficient of variation (CV) for glucose was 1.5% and 2%, naire was used to elicit information from each study participant for respectively; for cholesterol and triglycerides these were <2% the following variables: (i) demographic characteristics such as and <2.5%, respectively. HDL-C was estimated by the precipi- age, marital status, profession, education and socioeconomic tation method (phosphotungstate/Mg) and the inter- and intra- status; (ii) lifestyle-related factors such as dietary habits, physical assay CVs were <2.5%. Insulin concentrations were measured activity, tobacco and alcohol consumption; (iii) the health status by radioimmunoassay (Coat-a-Count insulin kit, Diagnostic of the individual and any history related to heart disease, stroke, Products). The intra- and interassay CVs were <5% and <7.5%, hypertension and diabetes. The presence of angina was assessed respectively. using the Rose angina questionnaire. If a person reported the presence of hypertension or diabetes or CVD (defined as the Definition of risk factors presence of CHD or stroke or angina), a detailed questionnaire The definitions used for the categorization of risk levels among the was administered to elicit information on control, awareness, participants are given in Box 1. treatment and limitations due to the illness. Each question was structured to gather as much information as possible without Statistical analysis increasing the duration of the interview, which usually lasted Statistical analysis was performed using the SPSS Version 9.0 about 30 minutes. package. Continuous data are summarized as means and standard deviations and categorical data as proportions. We used the Clinical measurements and anthropometry Student t test for comparing means and a chi-square test for A 30 second pulse rate was measured in each individual followed categorical variables. by 2 blood pressure measurements using a random zero sphygmo- manometer by standard techniques.28 The measurements were RESULTS obtained half an hour apart, either before or 1 hour after the first Of the 2935 eligible individuals (11.7% women), 2548 (86.8% of blood sampling. The lower of the two measurements was used for total, 266 women and 2282 men) agreed to participate in the study. this analysis. Height was measured in centimetres using a We report here the results of the men, as the number of women who stadiometer, which was calibrated to the nearest 0.5 cm, and were eligible and participated in the study was small (10.4%). Of weight was measured using a bathroom scale, which was vali- the 2282 men, 14 declined to undergo clinical examination or give dated on a daily basis with known weights. blood samples. Complete data for all the risk variables were Waist and hip circumferences were measured in the follow- available for 2122 subjects. ing manner. The subject was asked to stand with the arms by the sides and to breathe normally. The following points were marked Demographic characteristics on the right side: (i) the subcostal margin in the mid-axillary line, The mean age of the participants was 42 years. Nearly 60% of the (ii) the highest point of the iliac crest in the mid-axillary line. The participants were in the 41–50 years’ age group (Table I). A large

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Box 1. Definitions for different risk factors in the study

Hypertension: Systolic blood pressure (BP) >139 mmHg or diastolic BP >89 mmHg or history of treatment for hypertension Pre-hypertension: Systolic BP of 120–139 mmHg or diastolic BP of 80–89 mmHg in non-hypertensive subjects Diabetes: Fasting blood glucose >126 mg/dl or 2-hour post-load blood glucose >200 mg/dl or history of treatment for diabetes Impaired fasting glucose: Fasting blood glucose >100 mg/dl and <126 mg/dl, in the non-diabetic population Impaired glucose tolerance: Fasting glucose <126 mg/dl and 2-hour post-load blood glucose of 140–199 mg/dl in the non-diabetic population Tobacco use: Consumption of any form of tobacco in the past 6 months. The types of tobacco consumption considered included smoked (cigarettes, beedis and cigars), oral (tobacco chewed, pan masala, etc.) and inhaled forms (snuff) Hypercholesterolaemia: Total blood cholesterol levels >200 mg/dl Hypertriglyceridaemia: Fasting serum triglyceride levels >150 mg/dl Decreased high density lipoprotein cholesterol: Fasting blood HDL-cholesterol <40 mg/dl Adverse total cholesterol/high density lipoprotein cholesterol ratio: ≥4.5 Overweight: Body mass index* ≥25 kg/m2 Central obesity: Among men a waist circumference of >94 cm (as per the NCEP-ATP III guidelines for genetically high risk men) or a waist–hip ratio >0.90 as per the WHO criteria indicated central obesity Coronary heart disease (CHD): A positive history of CHD or presence of ECG abnormalities 1-1-1, 1-1-2, 1-1-3, 1-1-4, 1-1-5, 1-1-6 and 1-1-7 representing major Q waves; 4-1-1 and 4-1-2 representing ST–T changes and 5-1 and 5-2 representing T wave changes in the Minnesota coding system Metabolic syndrome: NCEP-ATP III criteria:32 For men, presence of >3 of the following: fasting plasma glucose levels >110 mg/dl, serum triglycerides >150 mg/dl, serum high density lipoprotein cholesterol <40 mg/dl, blood pressure >130/85 mmHg, and waist girth >102 cm. Use of waist circumference >94 cm suggested for men who might be genetically susceptible to insulin resistance WHO criteria:33 For men, insulin resistance in the top 25% of the population as measured by the euglycaemic–hyperinsulinaemic clamp method or the presence of impaired glucose tolerance or type 2 diabetes, and the presence of at least 2 of the following: abdominal obesity (waist–hip ratio >0.90 or body mass index >30 kg/m2), dyslipidaemia (serum triglycerides >150 mg/dl) or high density lipoprotein cholesterol <35 mg/dl, hypertension (>160/90 mmHg), or microalbuminuria *BMI is obtained by dividing the weight in kilograms by the square of the height in metres. Recent data suggest that this cut-off possibly underestimates obesity in Asians and hence we also report overweight using the cut-off of BMI ≥23 kg/m2 NCEP-ATP III National Cholesterol Education Program Adult Treatment Panel III

majority were educated with 66.4% having graduate, postgraduate TABLE I. Baseline characteristics of the study population (n=2122) or professional qualifications. Twenty-one per cent had secondary level education and the remaining 12.6% were illiterate (Table I). Characteristic Percentage The majority of employees were either skilled workers (47%) or Age group (years) professionals (26%). Semi-skilled and unskilled workers consti- 21–30 5.5 tuted 14% and 2.4% of the workforce, respectively. The remaining 31–40 25.4 41–50 59.2 were clerical staff (11.5%). 51–59 9.8 Educational achievements Risk factors No education or some education* 12.6 The mean values of various clinical, laboratory and anthropomet- Secondary school 21 ric measurements are given in Table I. The age-stratified and total Graduate/postgraduate/professional 66.4 prevalence of CVD risk factors are given in Table II. Normal blood pressure (systolic pressure <120 mmHg and diastolic pressure Clinical, laboratory, and anthropometric measurements Mean (SD) <80 mmHg, respectively) was observed in a quarter (25.6%) of the Mean age (years) 42 (6.5) individuals surveyed. The prevalence of pre-hypertension and Systolic blood pressure (mmHg) 122 (13.3) hypertension as per the Seventh Joint National Committee (JNC Diastolic blood pressure (mmHg) 83 (9.5) VII) criteria was 44% (95% CI: 42%–47%) and 30% (95% CI: Fasting blood glucose (mg/dl) 101 (32.6) Fasting serum insulin (IU/L)† 9.4 (16.7) 28%–32%), respectively. Among those with hypertension only Log insulin† 1.7 (0.8) one-third (31.5%) were aware of their blood pressure status. Of Total blood cholesterol (mg/dl) 180.5 (45.5) these, only 38% (12% of the total who were hypertensive) had their Low density lipoprotein cholesterol (mg/dl) 114.4 (43.5) blood pressure under control (<140/90 mmHg). The proportion of High density lipoprotein cholesterol (mg/dl) 36.4 (9.7) individuals with hypertension who were aware of their disease Serum fasting triglycerides (mg/dl) 149 (95) increased with age (from 19% of all those with hypertension in the Total/high density lipoprotein cholesterol ratio 5.3 (1.9) 20–29 years’ age group to 40.5% in the 50–59 years’ age group). Body mass index (kg/m2) 23.7 (3.4) Diabetes was present in 15% (95% CI: 14%–17%) and another Waist circumference (cm) 87.6 (10.3) 30.7% (95% CI: 29%–33%) had evidence of abnormal glucose Waist–hip ratio 0.97 (0.06) homeostasis, denoted by impaired fasting glucose. Impaired glu- *primary education †30 missing values, n=1812

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TABLE II. Overall and age-stratified prevalence (%) of risk factors Risk factor Total (95% CI) Age group (in years) 21–30 31–40 41–50 51–59 Hypertension 30 (28–32) 18.1 21 33.2 40.2 Pre-hypertension 44 (42–46) 55.2 55.1 41.7 40.2 Normal blood pressure 25.6 26.7 28.9 25.1 19.6 Diabetes 15 (14–17) 4.3 10.4 17.6 18.3 Normal glucose tolerance (fasting glucose <100 mg/dl) 48.1 52.2 50.2 47.0 46.6 Isolated impaired fasting glucose* (IFG) 23.6 34.8 25.0 22.1 22.6 Isolated impaired glucose tolerance† (IGT) 6.1 3.5 8.3 5.6 4.8 IFG and IGT combined 7.2 5.2 6.1 7.7 7.7 IFG or IGT 37 (35–39) 43.5 39.4 35.4 35.1 Total cholesterol >200 mg/dl 30.1 (28–32) 21.6 29.6 30.9 31.1 >240 mg/dl 9.8 (8.5–11) 6.0 9.6 10.3 9.6 Low density lipoprotein cholesterol >130 mg/dl 33 (31–35) 26 33 34 31.6 >160 mg/dl 13.6 (12–15) 9.5 14 14 13.4 High density lipoprotein cholesterol 67.2 (65–69) 66.4 69.1 67.1 63.2 Total/high density lipoprotein cholesterol ratio ≥4.5 62 (60–64) 53.4 60 64.1 56.5 Fasting triglycerides >150 mg/dl 38 (38–42) 19.8 36.1 38.9 46.4 >200 mg/dl 19.9 (18–22) 12.1 17.4 21.4 21.5 Tobacco use 48.3 Current tobacco smoking 36 (34–38) 15.5 35.6 37.0 41.1 Overweight (BMI ≥25 kg/m2) 35 (33–37) 18.1 29.1 37.2 44.5 Obese (BMI ≥30 kg/m2) 3.3 (2.6–4.1) 0 2.4 4.0 3.8 BMI ≥23 kg/m2 58.5 (56.4–60.6) Central obesity (waist circumference >102 cm) 7.2 (6.0–8.3) 0 4.6 7.9 13.4 Waist circumference >94 cm 26.5 (25–28) 5.2 18.1 29.9 39.7 >90 cm 43 (40–45) 10.3 32.2 47.7 56.5 Waist–hip ratio ≥0.95 66.6 (64.6–68.6) 28.4 54.6 73.4 77.5 ≥0.90 88.7 (87.3–90.0) 66.4 84.1 92.0 93.3 Presence of ≥2 major risk factors‡ 47 23.5 39 51.3 51.4

CI confidence interval BMI body mass index * after excluding IGT from the analysis † after excluding IFG from the analysis ‡ hypertension, diabetes, current smoking, and total/high density lipoprotein cholesterol ratio ≥4.5

cose tolerance, an indicator of insulin resistance, was observed in risks associated with BMI in Asians, 12.2% were in the ‘high to 13.2% (95% CI: 12%–15%) of participating individuals (Table II). very high’ risk (BMI ≥27.5 kg/m2) category and 58.5% in the While 31% of those with diabetes were aware of their status, in only ‘moderate to high risk’ (BMI ≥23 kg/m2) category29 (Table II). 17% of these (5% of the people with diabetes) was the blood glucose Similarly, very few individuals were centrally obese by the Na- controlled to normoglycaemic levels (fasting plasma glucose <100 tional Cholesterol Education Program (NCEP) criteria of waist mg/dl and postprandial glucose <140 mg/dl)). The proportion of circumference >102 cm (7.2%). However, 43% (95% CI: 40%– individuals with diabetes who were aware of their disease increased 45%) of the individuals had a waist circumference ≥90 cm, the with age (from 20% of all those with diabetes in the 20–29 years’ proposed criteria for central obesity in men in the Asia-Pacific age group to 42.1% in the 50–59 years’ age group). region,30 while 26.5% (95% CI: 25%–28%) had a waist circumfer- Hypercholesterolaemia (total cholesterol ≥200 mg/dl) was ence >94 cm, the proposed first action level in the Caucasian observed in 30.1% (95% CI: 28%–32%) of individuals, and population.31 hypertriglyceridaemia (serum fasting triglycerides ≥150 mg/dl) in The metabolic syndrome was present in 28.1% (95% CI: 26%– 38% (95% CI: 38%–42%) of those surveyed (Table II). A large 30%) of the study population (Table III) by the NCEP Adult proportion (67.2% [95% CI: 65%–69%]) of individuals had low Treatment Panel (ATP) III criteria (see Box 1).32 Using the criteria HDL-C levels (serum HDL-C <40 mg/dl), which resulted in for genetically susceptible populations (waist circumference >94 nearly two-thirds (62%) of individuals having a total cholesterol/ cm instead of 102 cm), the prevalence of the metabolic syndrome HDL-C ratio of ≥4.5. Overall, this population had a high rate of was higher (35%). Using the modified WHO criteria33 for defining tobacco use (48.3%); 36% of the individuals were current smokers the metabolic syndrome (see Box 1 and Table III), the prevalence (cigarettes 21.5% and beedis 19.7%), and one-quarter of the was 29% (95% CI: 27%–31%). The prevalence of the metabolic population used non-smoking forms (Table II). The commonest syndrome using the modified NCEP definition was 29% after non-smoking form of tobacco use was chewing tobacco or pan individuals with diabetes were excluded, and 21.7% when only masala mixed with tobacco. individuals with normoglycaemia were considered. Among 1798 One-third of the population (35% [95% CI: 33%–37%]) was individuals without diabetes, fasting serum insulin levels were overweight using the traditional cut-off of BMI ≥25 kg/m2. How- available for 1552 persons. The mean and median values of insulin ever, as per the recent WHO recommendations for defining health were 8.8 IU/L and 5.0 IU/L, respectively. After log transformation

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TABLE III. Prevalence (%) of the metabolic syndrome (n=2120) Only 15% of the study population were free from any of the risk Criteria for metabolic syndrome Total Age group (in years) factors (hypertension, diabetes, current smoking and total choles- terol/HDL-C ratio ≥4.5). While 85% of the study population had 21–30 31–40 41–50 51–59 at least 1 of these risk factors, about 47% of the employees had at NCEP criteria 28.1 12.9 23.4 29.8 38.3 least 2 co-existing risk factors. NCEP modified criteria* 35.3 14.7 29 37.9 47.8 Modified WHO criteria† 29 16.4 25.8 30.6 34.6 Effect of age on CVD risk factors NCEP National Cholesterol Education Programme While diabetes, hypertension, hypertriglyceridaemia, overweight, * Waist circumference >94 cm (in genetically susceptible populations); other criteria are the same central obesity and the metabolic syndrome, as well as the pres- † Revised definition of WHO metabolic syndrome: microalbuminuria not included as a ence of multiple risk factors showed rising trends with age, the criterion; blood pressure (BP) thresholds for defining hypertension taken as systolic BP prevalence of smoking, low HDL and adverse total cholesterol/ ≥140 mmHg and diastolic BP ≥90 mmHg; dysglycaemia defined as presence of diabetes or impaired fasting glucose or impaired glucose tolerance (insulin parameters not used) HDL-C ratio was roughly similar in all the age groups (Table II). Even the youngest age group of 20–29 years had a high prevalence of risk factors such as dyslipidaemia, hypertension and diabetes. of insulin values to make the distribution normal, the mean values of insulin were consistently higher in those with the metabolic Effect of adiposity on CVD risk factors syndrome as compared to those without (1.9 and 1.67, respec- There was a continuous graded increase in mean values as well as tively, among those with and without the metabolic syndrome, p risk factor prevalence with increasing BMI (Fig. 1) and waist for difference <0.001) irrespective of the way the metabolic circumference (Fig. 2). The risk of developing obesity-associated syndrome was defined. risk factors started to rise much below the defined thresholds for

80 70 68 70 62 60 52 54 49 46 50 44 47 40 37 34 35 25 30 19 23

Percentage 17 16 16 20 9 10 10 0 Hypertension Diabetes TC:HDL ratio* Metabolic PPresenceresence of ≥ 22 ≥4.5 syndrome† majorMajor risk risk factors factors

Quartile I Quartile II Quartile III Quartile IV

FIG 1. Prevalence of risk factors in the four quartiles of body mass index (all values in kg/m2) Quartile I: 13.9–21.2; Quartile II: 21.3–23.7; Quartile III: 23.8–25.8; Quartile IV: 25.9–37.2 *TC:HDL ratio total cholesterol:high density lipoprotein cholesterol ratio †Metabolic syndrome as defined by the NCEP-ATP III but excluding waist circumference from the definition

80 70 67 70 61 55 60 53 49 50 44 45 38 40 36 33 34 30 24 19 23 Percentage 17 20 16 15 10 9 10 0 Hypertension Diabetes TC:HDL ratio Metabolic Presence of ≥2 ≥4.5* syndrome† major risk factors

Quartile I Quartile II Quartile III Quartile IV

FIG 2. Prevalence of risk factors in the four quartiles of waist circumference (all values in cm) Quartile I: 51.4–81.0; Quartile II: 81.1–88.0; Quartile III: 88.1–94.5; Quartile IV: 94.6–131 *TC:HDL ratio total cholesterol:high density lipoprotein cholesterol ratio †Metabolic syndrome as defined by the NCEP-ATP III but excluding waist circumference from the definition

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western populations (BMI >25 kg/m2 and waist circumference underscores the importance of insulin resistance among Indians. >94 cm). We explored the causes for the high prevalence of the metabolic syndrome in our study population and found overweight and Prevalence of CVD central obesity to be major correlates of these risk markers (Figs. A past history of diagnosed CHD and stroke was identified in 16 1 and 2). As there is a pronounced urban–rural gradient in obesity (0.8%) and 7 (0.3%) individuals, respectively. The prevalence of among Asian Indians,43 we believe that the high prevalence of risk CHD, defined as history of CHD (identified by the modified Rose markers such as impaired glucose tolerance, the metabolic syn- questionnaire) or presence of ECG abnormalities suggestive of drome and high-normal blood pressure, all of which are influ- CHD (by specified Minnesota codes), was noted in 7.3% of men. enced by body fat, is a reflection of the current urbanization and Abnormal ECGs suggestive of CHD in the form of Q waves, T adaptation of a western lifestyle among the Indian population. The wave and ST–T abnormalities were observed in 2.5% of the prevention and management of the metabolic syndrome largely population studied. involves lifestyle modifications. Recently published clinical trials such as the Diabetes Prevention Programme44 and the Finnish DISCUSSION diabetes prevention studies45 have established the importance of Our study on the cardiovascular risk profile in a industrial work- lifestyle measures in the prevention of diabetes. Similarly, a low place setting in India, among a relatively young urban population, level of physical activity and a diet rich in saturated fats and high found the prevalence of traditional risk factors to be high. Even in glycaemic foods have been implicated in the pathogenesis of the the 20–29 years’ age group, only one-quarter of the individuals metabolic syndrome.46 had normal blood pressure, only half had normal glucose toler- While such a high prevalence of risk factors is a cause for ance, more than half had dyslipidaemia, one-fifth were over- concern, organized sector industries provide a unique opportunity weight, and more than one-fifth had at least 2 major risk factors. for carrying out prevention programmes. It is estimated that there Awareness and control of hypertension and diabetes was poor, are nearly 6 million people working in such large organized sector indicating low detection and poor management of major CVD risk industries in India. While most of these have their own primary factors. The high prevalence of ‘risk markers’ such as impaired healthcare facilities, they also provide for the healthcare of employ- fasting glucose and glucose tolerance, and pre-hypertension sug- ees and their dependents in higher medical institutions when gests that there is a large vulnerable population which can develop required. With the rising burden of CVD, the expenditure on such an overt adverse risk profile and CVD in the future. healthcare programmes by every industry is likely to increase Community-based cross-sectional surveys and other studies enormously. Thus, there is a lot of scope for and benefit in initiating carried out in the past few decades have revealed a high and comprehensive, low-cost CVD prevention programmes at the work- increasing prevalence of CVD and its risk factors in individuals of place for employees and their dependants. Such onsite programmes South Asian origin residing, in India as well as in other coun- have been found to be modestly successful in the West through tries.5–11,34–37 However, not many of these have evaluated the CVD increased awareness, health education and risk reduction interven- risk profile in younger populations. The disconcertingly low level tions, and modified models could easily be adapted to Indian of awareness of CVD and its treatment further increases the risk settings. This is likely to lead to a healthier workforce as well as a for future morbidity and mortality due to CVD. The low awareness decrease in expenditure by the industry on treatment costs and and control noted in our population is similar to data published increased absenteeism. We hope that our study will provide the from other developing countries such as China. Tao et al.38 from stimulus for initiating such surveillance and preventive activities. their nationwide survey of blood pressure of more than 950 000 The prevalence rates that we have reported are based on men and women, found that of all the hypertensives, only 25% western cut-offs and we require a longitudinal evaluation of our were aware of their hypertensive status and, among those aware, study population on CVD morbidity and mortality to fully under- only half were on any blood pressure lowering medications. stand the implications of our findings. To address the above Overall, in only 3% was the blood pressure controlled to normal issues, and to document changes in risk factors and prospectively levels, although this had improved by 2000–01.39 Further, a recent identify determinants of CVD, we are continuing our study in this report highlights the urban–rural differences in the awareness, industrial population. treatment and control of hypertension. The Hypertension Study Group40 while noting similar low rates of awareness and control, Limitations identified visit to a physician in the previous 1 year, higher As the study was carried out in an industrial setting, it may not be educational attainment and female gender to be important corre- representative of the general population. Though we have pro- lates of awareness among a cross-section of subjects with hyper- vided age-specific prevalence rates, the industrial population is tension from India and Bangladesh. Therefore, while opportunis- different from the general population in terms of its socioeconomic tic screening may identify individuals with undetected hyperten- profile. However, this study is broadly generalizable to similar sion and diabetes, we need specific strategies to improve the large, organized sector workforce involving nearly 6 million control and therapy of those with CVD risk factors. employees. Further, our study population comprised predomi- The importance of insulin resistance in determining the high nantly young men. Also, women comprised only 10% of the mortality due to CVD among Indians has been highlighted by workforce. The results of this study cannot be generalized to McKeigue41 and Hughes.42 Based largely on data obtained from individuals older than 60 years, in whom the risk factor as well as migrant Indians and comparing them to indigenous populations, disease burden will be even higher than that reported in this Indians were believed to have an enhanced propensity to insulin population. resistance and CVD.41 Though others have questioned the role of insulin resistance and emphasized the importance of conventional CONCLUSION risk factors such as lipids, the high prevalence of the metabolic We have demonstrated a high prevalence of CVD risk factors, its syndrome and its association with hyperinsulinaemia indirectly markers such as the metabolic syndrome and risk determinants

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such as obesity (both generalized and central) among a group of serum cholesterol concentration lower risk of ischaemic heart disease? BMJ young men. Though the study population was not representative 1994;308:367–72. 21 Lewington S, Clarke R, Qizilbash N, Peto R, Collins R. Prospective studies collaboration. of the national population (older, only men, higher educational Age-specific relevance of usual blood pressure to vascular mortality: A meta-analysis of and socioeconomic strata), we believe that it does represent the individual data for one million adults in 61 prospective studies. Lancet 2002;360: rising trend of CVD in urban India. Despite the availability of 1903–13. 22 MacMahon S, Peto R, Cutler J, Collins R, Sorlie P, Neaton J, et al. Blood pressure, onsite healthcare and a high level of education as compared to the stroke, and coronary heart disease. Part 1. Prolonged differences in blood pressure: general population, the awareness and treatment of hypertension Prospective observational studies corrected for the regression dilution bias. Lancet and diabetes is low. Therefore, there is a pressing need to initiate 1990;335:765–74. 23 Stratton IM, Adler AI, Neil HAW, Matthews DR, Manley SE, Cull CA, et al. onsite preventive programmes to identify and manage individuals Association of glycaemia with macrovascular and microvascular complications of type at high risk for future CVD. 2 diabetes (UKPDS 35): Prospective observational study. BMJ 2000;321:405–12. 24 Fuller JH, Shipley MJ, Rose G, Jarrett RJ, Keen H. Coronary-heart-disease risk and ACKNOWLEDGEMENTS impaired glucose tolerance. The Whitehall study. Lancet 1980;1:1373–6. 25 Vasan RS, Larson MG, Leip EP, Evans JC, O’Donnell CJ, Kannel WB, et al. Impact The International Clinical Epidemiology Network (INCLEN) provided partial of high-normal blood pressure on the risk of cardiovascular disease. N Engl J Med financial support for this study. 2001;345:1291–7. We gratefully acknowledge the cooperation of the employees and the 26 Lakka HM, Laaksonen DE, Lakka TA, Niskanen LK, Kumpusalo E, Tuomilehto J, et management of Bharat Electronics Limited for participating in this study, Dr S. al. The metabolic syndrome and total and cardiovascular disease mortality in middle- K. Puri and Dr Medha Joshi for providing clinical support at the industrial site, aged men. JAMA 2002;288:2709–16. A. Karthika for data management, and all the research and support staff, without 27 Lorenzo C, Okoloise M, Williams K, Stern MP, Haffner SM. The metabolic syndrome whom this study would not have been possible. as predictor of type 2 diabetes: The San Antonio heart study. Diabetes Care 2003;26:3153–9. 28 Elliott P, Stamler R. 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