Study design and participants

The methods and population characteristics of the PURE study have been described previously [12]. In Colombia, the Ethics Committee of the Cardiovascular Foundation of Colombia approved the study. With the purpose of obtaining an adequate geographical and social representation of the country, participants were selected from urban and rural communities from 11 of the most populated departments (states) [13]. The study sample was recruited from 2005 to 2009. A multistage convenience sample survey was used. During the first and second stages, the departments and communities were selected. In the third stage, a representative sample of households was recruited, using a community-sampling framework. The primary sample unit was the community defined as a geographical area, in which a group of people with common characteristics lived. The urban area was defined as the capital city of each department together with its metropolitan area. Households were defined and selected as part of the rural sample if located at least 50 km from an urban center, had a population of 5,000 inhabitants or less, and were at least to 45 minutes of distance from a local referral hospital.

In general, households were eligible if at least one member was 35–70 years old and if the members intended to continue living at their current address for the next four years. All eligible individuals who provided written informed consent were enrolled.