RESIDENCE AT HIGH ALTITUDE IS ASSOCIATED WITH LOWER CONVENTIONAL AND AMBULATORY BLOOD PRESSURE THAN LIVING AT SEA LEVEL IN THE GENERAL POPULATION OF PERU. HIGHCARE-LAPS STUDY

Objective: Acute exposure to hypoxia at high altitude (HA) leads to an increase in blood pressure (BP) in healthy individuals and in hypertensive patients. Little is known, however, about the effect of long-term HA residence on BP. Available data based on conventional BP measurements are inconsistent and no general population studies using 24-h ambulatory BP monitoring (ABPM) have been conducted. Aim of HIGHCARE-LAPS was to compare BP levels and cardiovascular risk profile among population-based samples of subjects residing in Peruvian communities living at different altitudes. BP-related data are reported in this paper. Design and method: Study participants were recruited by sex- and age-stratified random multistage cluster sampling from the general adult population residing permanently in urban areas at different altitudes in Peru (Lima, <500m, Huancayo 3287m, Juliaca 3824m, Cerro de Pasco 4330m). In all participants questionnaire-based information, conventional BP (3 seated measurements with a validated oscillometric device, HEM7121 OMRON, Japan), 24-hour ambulatory BP (A&D TM2430, Japan) and laboratory variables were obtained. Results: The study included 206 lowlanders and 595 highlanders. Highlanders were slightly younger, had lower BMI, oxygen saturation and prevalence of antihypertensive medication use and higher haematocrit. In highlanders all conventional and ambulatory BP values were lower and heart rate values higher than in lowlanders. Comparisons between lowlander and highlander samples and for individual sites at different altitudes are reported in the Table. The difference in 24-hour systolic BP between highlanders and lowlanders remained significant (7.2 mmHg, p<0.001) in a linear multiple regression model adjusting for age, sex, BMI, 24-hour heart rate, respiratory rate, and haematocrit. These covariates were selected by LASSO method from a set also including lifestyle-related variables. Conclusions: Permanent residence at high altitude is independently associated with lower conventional and ambulatory BP levels than low altitude residence in the general population of Peru. This relationship does not seem to be explained by lifestyle differences. Mechanisms behind this difference and its impact on cardiovascular risk should be further investigated. Also, comparative studies with other highland populations with different adaptive characteristics would allow to understand better the effects of HA residence on cardiovascular health.