The Chennai Urban Rural Epidemiology Study (CURES)--study design and methodology (urban component) (CURES-I).

The report of World Health Organization (WHO) shows that India tops the world with the largest number of diabetic subjects. This increase is attributed to the rapid epidemiological transition accompanied by urbanization, which is occurring in India. There is very little data regarding the influence of affluence on the prevalence of diabetes and its complications particularly retinopathy in the Indian population. Furthermore, there are very few studies comparing the urban/rural prevalence of diabetes and its complications. The Chennai Urban Rural Epidemiology Study (CURES) is designed to answer the above questions. CURES is initially planned as a cross-sectional study to evolve later into a longitudinal study. Subjects for the urban component of the CURES have been recruited from within the corporation limits of Chennai City. Chennai (formerly Madras), the largest city in Southern India and the fourth largest in India has been divided into 10 zones and 155 wards. 46 wards were selected by a systematic random sampling method to represent the whole of Chennai. Twenty thousand and one individuals were recruited for the study, this number being derived based on a sample size calculation. The study has three phases. Phase one is a door to door survey which includes a questionnaire, anthropometric, fasting capillary blood glucose and blood pressure measurements. Phase two focussed on the prevalence of diabetic complications particularly retinopathy using standardized techniques like retinal photography etc. Diabetic subjects identified in phase one and age and sex matched non-diabetic subjects will participate in these studies. Phase three will include more detailed studies like clinical, biochemical and vascular studies on a sub-sample of the study subjects selected on a stratified basis from phase one. CURES is perhaps one of the largest systematic population based studies to be done in India in the field of diabetes and its complications like retinopathy, nephropathy and neuropathy.