Impact of comprehensive cardiovascular risk reduction programme on risk factor clustering associated with elevated blood pressure in an Indian industrial population

Systolic blood pressure (SBP) exceeding 115 mmHg contributes to one-half of ischaemic heart disease (IHD) and cerebrovascular disease (CeVD) around the world1. The major contributors of this global burden of blood pressure (BP) are emerging economies like India and China as a consequence of increased life-expectancy, urbanization, development and affluence2. Several epidemiologic studies have demonstrated that systolic and diastolic BP have a strong, continuous, graded and positive association with cardiovascular disease (CVD) outcomes or life time risk of CVD with no indication of a critical value3–5. Nevertheless, clinical management strategies typically use BP thresholds for interventions to reduce BP associated risk6. Hypertension appears to cluster with other metabolic risk factors like dyslipidaemia, glucose intolerance, hyperinsulinaemia, obesity, and hyperuricaemia more than would be expected by chance7,8. In the Framingham study, hypertension in isolation was observed in less than 20 per cent of the time9. The reasons for this metabolic clustering include insulin resistance and sympathetic overactivity. Further, the tendency for these atherogenic traits to cluster with elevated BP increased stepwise with the degree of obesity9. The Indian population is considered a metabolically high risk group and this population is demonstrated to have higher levels of visceral adiposity, insulin resistance, and novel risk markers such as C-reactive protein (CRP), adiponectin and plasma leptin10,11. The clustering of CVD risk factors with BP has not been studied before in the Indian population. Demonstration of such clustering is important for formulating risk reduction strategies particularly in individuals with stage I hypertension or prehypertension which are widely prevalent than severe stages of hypertension. Here we report the clustering effect of CVD risk factors with suboptimal BP in a large Indian population and the impact of risk reduction interventions on risk factor clustering.