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Title: Incidence of cardiovascular risk factors in an Indian urban cohort. Results from the New Delhi Birth Cohort

Authors: M Huffman, D Prabhakaran, C Osmond, C Fall, et al

Reference: JACC 2011; 57:1765-1774
http://bit.ly/iDHZs4

Reviewer: Robert Goldberg, PhD, Contributing editor, ProCor; Professor of Medicine and Epidemiology, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA

Reviewer comments: India has one of the highest burdens from CVD in the world and the number of deaths attributed to CVD is expected to increase from approximately 2.3 million in 1990 to more than double this number by 2020.

Despite the burden of fatal and nonfatal events of CVD in India, limited data are available describing either the incidence or prevalence rates of various CVD risk factors in this population and the factors that may negatively impact the development of these coronary predisposing factors. Data from the multi-country INTERHEART Study suggest that certain risk factors for CVD, including hypertension, abdominal obesity, and diabetes, are higher among Indians than among other ethnic groups throughout the world, raising concerns about a future epidemic of CVD in India.

The results of the present observational study, in a comparatively young cohort of men and women enrolled in the New Delhi Birth Cohort, suggest that the magnitude of important coronary risk factors is unfortunately increasing in this population. Indeed, both the magnitude of prevalent and newly developed important coronary risk factors increased over the approximate 7 year follow-up of the present longitudinal investigation.

While the reasons for these negative trends are unclear, and multi-factorial, they likely include ongoing negative lifestyle and dietary changes associated with the transition to an urban lifestyle and accompanying socioeconomic development in the Indian population. While unknown, the high rates of several metabolic disorders in this relatively young population may also be related to factors associated with childbirth, including maternal malnutrition and child's low birth weight, which have implications for the more optimal pre-natal care of pregnant women.

Irrespective of the reasons behind these disturbing trends, changes in these important coronary predisposing factors bear watching in the future. More importantly, the present data emphasize the need for early intervention and health promotion programs in children and young adults living in India as well as in other developing and developed countries.

Purpose of study: To examine the development of risk factors for CVD in a young (age 29-36 years) urban Indian population and factors associated with increased risk of these coronary disease predisposing factors.

Location of study: New Delhi, India

Study design: Prospective

Results: Data for the present investigation were derived from the New Delhi Birth Cohort project. This is a large cohort study of more than 20,000 married women of reproductive age from New Delhi, that was initiated in the late 1960's, in whom their offspring were studied over a prolonged period of time. Anthropometric and survey data were collected during a number of distinct study phases with, unfortunately, a considerable loss to attrition over these serial exams. The data for the present investigation were utilized from study Phase 5, which was carried out between 1998 and 2002, and from study Phase 6, which was carried out between 2006 and 2009. Home visits were carried out by trained personnel and information was collected from consenting study subjects about the participant's medical history, medication use, alcohol intake, and smoking; standardized measurement of participant's blood pressure, height, weight, and waist circumference, and serum glucose and lipid levels was carried out.

A total of 1100 men (n=652) and women (n=448) participated in the present study. The average age of study participants was 29 years, their average BMI was nearly 25, and the average systolic BP was 130 mmHg in men and 119 mmHg in women. Participants were followed for an average of nearly seven years between study phases 5 and 6.

In terms of the development of selected risk factors, the annual incidence rates of obesity were 2.0% and 2.2% for men and women, respectively. The average BMI and measures of waist and hip circumference all increased in both men and women between study phases 5 and 6. For example, the average BMI increased from 25 to 27 in both men and women resulting in an increase in obesity from 9% to 21% in men and from 13% to 25% in women during the approximate seven-year period under study.

The annual incidence rates of hypertension averaged 4.2% in men and 1.8% in women and the average systolic BP increased by 11 mmHg in men and by a similar amount in women between study phases 5 and 6. Similarly, the prevalence of hypertension markedly increased from 11% to 34% in men and from 5% to 15% in women during the years under study.

With regards to diabetes, the annual incidence rates of diabetes remained low, averaging approximately 1% for men and half that for women. On the other hand, there was a considerable increase in the prevalence rates of diabetes during the years under study with a doubling in the prevalence of diabetes in both men (5% to 12%) and women (4% to 7%).

Finally, total serum cholesterol levels increased by an average of 5 mg/dl in men and by 6 mg/dl in women between follow-up exams 5 and 6. On the other hand, LDL-cholesterol levels did not appreciably change in men or in women between exams 5 and 6 whereas serum levels of HDL cholesterol increased slightly in men and in women. The use of lipid lowering therapy was reported by approximately 1% of study subjects at the time of their most recent assessment.