- In 1990, a community survey of 13,723 adults (25-64 yr) in Delhi, the nations capital, showed a coronary artery disease (CAD) prevalence of 9.6%.1 No CAD prevalence data has been published since then.
- The prevalence of risk factors are high but the awareness and control is poor. A large study in a young male population (mean age 42) showed a high prevalence of major risk factors: obesity 35%, abdominal obesity 43%, diabetes 15%, prediabetes 37%, prehypertension 44%, current smoking 36%, and high serum total cholesterol/ HDL ratio (> 4.5) 62%. Metabolic syndrome was present in 28%-35% of the individuals depending on the diagnostic criteria used.2
- In this and other studies the prevalence of risk factors increases with age, except for smoking (possibly because many of the smokers die young).2
- Despite high prevalence, the general public has a poor knowledge of modifiable risk factors for CAD.3 More than one-third of diabetes and high blood pressure are undiagnosed.2 About 9% of those with high blood pressure had coexisting diabetes and 8% were suffering from CAD.4
- The prevalence of high blood pressure in adults is 28%, but only 53% of them were aware of the diagnosis, 43% were taking treatment, and only 11% had controlled blood pressure.
- High blood pressure was found in 12% of the boys and 11% of girls in New Delhi and was highly correlated with obesity in a study of 10,215 school children (5-14 years) in Delhi.5
- The prevalence of obesity has increased steadily in children and has reached 24% by 2006-2007. The prevalence among adolescent children was 29% in private schools and 11% in government funded schools indicating the important role of affluence.6
The New Delhi Birth Cohort
- A recent report from the New Delhi Birth Cohort sheds new light on the dynamics of the escalating prevalence of CVD risk factors in young Indians. The investigators reported the changes in risk factors among 1,100 young adult participants (mean age at baseline 29 years) followed for an average of 7 years.7
- The average annual incidence of obesity was 2.0% in men and 2.2% in women. Average high blood pressure incidence was 4.2% and 1.8% per year and the incidence of diabetes was 1.0% and 0.5% per year in men and women, respectively. 7
- By the end of follow-up, the mean body mass index (BMI) was 27 kg/m2 in both sexes, and the prevalence of central obesity (a waist circumference of >90 cm for men or 80 cm in women) was 70% in men and 71% in women.7
- The prevalence of obesity had increased to 64% using Indian criteria (BMI >25) but was low at 20% using the Europid criteria (BMI >30) (Figure 019).7 The figures for women were 65% and 25% respectively.7
- The prevalence of high blood pressure tripled in men and women (reaching 34% and 15%, respectively), whereas the prevalence of diabetes doubled, reaching 12% in men and 7% in women at a mean age of only 36 years.7
- The incidence rate of obesity was higher in women compared with men, but the incidence rates of high blood pressure and diabetes were higher in men.7
- The high incidence and prevalence of obesity, high blood pressure, and diabetes in this young, urban Indian cohort explains the tsunami of heart disease in India.7
- The high rates of metabolic disturbances— central obesity, high blood pressure, dyslipidemia, prediabetes, and diabetes—may also be related to abnormal life-course events, such as maternal undernutrition, low birth weight, and subsequent adiposity rebound. Lower weight in infancy, and greater childhood and adolescent BMI have previously been shown to be associated with an increased risk of adult high blood pressure, prediabetes, and diabetes in this cohort.8
- The steep increase in prevalence of these diseases and the young age at which they occur, may ultimately slow economic growth because premature deaths and disability lead to declines in the active work force and reduction in productivity (see Economic Burden).9
- The causes of these escalating risk factors are complex, but likely include lifestyle changes associated with urbanization and the epidemiologic and nutritional transitions that accompany economic development.10 The speculations include increased urban and socioeconomic development associated with increased caloric intake (particularly of energy dense foods) and decreased physical activity.7
- Despite their high prevalence, conventional risk factors could not fully explain the high prevalence of CAD in a case control study in New Delhi. The population-attributable risk was highest for low HDL (44%), low education status (7%), diabetes (6%), family history of premature CVD (4%), low fruit consumption (4%), tobacco abuse (4%), full-cream milk consumption (4%) or milk intake (3%), high fasting blood glucose (2%), and history of high blood pressure (2%).11 This further underscores the role of genetic risk factors like lipoprotein(a) which was not evaluated in Delhi.
1. Chadha S. L., Radhakrishnan S, Ramachandran K, Kaul U, Gopinath N. Epidemiological study of coronary heart disease in urban population of Delhi. Indian J Med Res. Dec 1990;92:424-430.
2. Prabhakaran D, Shah P, Chaturvedi V, Ramakrishnan L, Manhapra A, Reddy KS. Cardiovascular risk factor prevalence among men in a large industry of northern India. Natl Med J India. Mar-Apr 2005;18(2):59-65.
3. Saeed O, Gupta V, Dhawan N, et al. Knowledge of modifiable risk factors of Coronary Atherosclerotic Heart Disease (CASHD) among a sample in India. BMC Int Health Hum Rights. 2009;9:2.
4. Chaturvedi S, Pant M, Yadav G. Hypertension in Delhi: prevalence, awareness, treatment and control. Trop Doct. Jul 2007;37(3):142-145.
5. Chadha S. L., Tandon R, Shekhawat S, Gopinath N. An epidemiological study of blood pressure in school children (5-14 years) in Delhi. Indian heart journal. Mar-Apr 1999;51(2):178-182.
6. Bhardwaj S, Misra A, Khurana L, Gulati S, Shah P, Vikram NK. Childhood obesity in Asian Indians: a burgeoning cause of insulin resistance, diabetes and sub-clinical inflammation. Asia Pac J Clin Nutr. 2008;17 Suppl 1:172-175.
7. Huffman M D, Prabhakaran D, Osmond C, et al. Incidence of cardiovascular risk factors in an Indian urban cohort results from the new delhi birth cohort. J Am Coll Cardiol. Apr 26 2011;57(17):1765-1774.
8. Bhargava SK, Sachdev HS, Fall CH, et al. Relation of serial changes in childhood body-mass index to impaired glucose tolerance in young adulthood. N Engl J Med. Feb 26 2004;350(9):865-875.
9. Paradis G, Chiolero A. The cardiovascular and chronic diseases epidemic in low- and middle-income countries a global health challenge. J Am Coll Cardiol. Apr 26 2011;57(17):1775-1777.
10. Omran AR. The epidemiologic transition: a theory of the epidemiology of population change. 1971. Milbank Q. 2005;83(4):731-757.
11. Jain P, Bhandari S, Siddhu A. A case-control study of risk factors for coronary heart disease in urban Indian middle-aged males. Indian Heart J. May-Jun 2008;60(3):233-240.