High blood pressure (BP) is one of the principal cardiovascular risk factors. While BP levels and hypertension prevalence are well characterized in many populations, information on BP and on cardiovascular risk profile in high altitude inhabitants is limited and frequently contradictory, especially in the large highland populations of South America. The information on the effects of permanent high altitude exposure on cardiovascular variables including BP may be relevant in the light of the known BP-increasing effect of acute exposure to high altitude hypoxia. This information may have practical implications for millions of people living at elevated altitudes in Asia, South America and Africa.

The inconclusive epidemiological evidence on BP and cardiovascular risk in high altitude dwellers may be the result of several factors, among them: 1) confounding by genetic and socio-economic factors; 2) imperfect methods of BP evaluation, in particular lack of data on ambulatory and home BP (both methods considered superior to conventional clinic BP in the assessment of exposure to high BP).

On this background, the general aim of the study is to compare blood pressure levels and cardiovascular risk profile among population-based samples of subjects residing in Peruvian communities living at different altitudes.

Inclusion Criteria:

• Adult (>18 years) male and female subjects;
• Highlanders: permanence at high (>2500 m) altitude;
• Lowlanders: permanence at low (<1500 m) altitude;
• Written informed consent to participate in the study

Exclusion Criteria:

• Lowlanders who over 3 months preceding inclusion in the study spent considerable (> 7 consecutive days) amount of time at altitudes above 1500 m;
• Highlanders who over 3 months preceding inclusion in the study spent considerable (>7 consecutive days) amount of time at altitudes below 2500 m;
• Subjects cognitively incapable of providing informed consent or responding to a questionnaire
• Physical disability that would prevent study assessments from being performed
• Active pulmonary tuberculosis
• Pregnancy

Study participants will be recruited by random sampling from the general population residing permanently in urban areas at:

1. Sea level (lowlanders): <500m altitude (the city of Lima and surroundings, population 7.605.742)

2. High altitude (highlanders):

   • 2500-3500 m (Cajamarca, 2,720 m, population 283.767; Cuzco, 3,399 m, pop. 420.137; Huancayo, 3.287m, pop. 501.384)
   • 3500-4000 m Juliaca, 3,824 m, pop. 216.716,
   • >4000 m (Ananea, 4.616m, pop. 20.572; La Rinconada 5.100m, pop. 50.000; Cerro de Pasco, 4.300-4.700 m, pop. 70.000)

The data will be placed in a public repository and available upon reasonable request after study completion