P063 DIFFERENCES IN CARDIOVASCULAR RISK IN THE GENERAL POPULATION OF LOW AND HIGH-ALTITUDE RESIDENTS IN PERU. HIGH ALTITUDE CARDIOVASCULAR RESEARCH – LATIN AMERICA POPULATION STUDY

Abstract

Background and Objective. Previous data in a convenience sample of highlanders showed an elevated prevalence of masked hypertension. However, comparative studies describing the prevalence of blood pressure (BP) phenotypes in the general population atof different altitudes are lacking. Our aim was to compare the prevalence of BP phenotypes defined by office BP measurement and ambulatory BP monitoring (ABPM) in a population-based sample of Peruvian lowlanders and highlanders. Methods. Sex- and age-stratified random general adult population sample was recruited in urban areas at low (Lima, <500m) and high altitude (Huancayo 3287m, Juliaca 3824m, Cerro de Pasco 4330m). Questionnaires, anthropometric data, conventional BP (3 seated measurements with a validated oscillometric device), 24-hour ambulatory BP (A&D TM2430, Japan), and blood analyses were obtained. BP was defined as elevated if either systolic or diastolic BP was: 1) office (OBP) ≥140/90; 2) 24-hour ≥130/80; 3) Daytime ≥135/85; 4) Night-time ≥120/70 (all in mmHg). BP phenotypes were defined as: normotension (NT) – no BP values elevated; white coat hypertension (WCH) – only OBP elevated; masked hypertension (MH) – any ambulatory BP elevated, normal OBP; sustained hypertension (SH) – OBP and any ambulatory BP elevated Results. The analysis included 181 lowlanders and 553 highlanders. Highlanders had slightly lower age (45 vs. 47 years, p=0.005), BMI (26.7 vs. 28.6 kg/m2, p<0.001), and oxygen saturation (88.9 vs. 97.8%, p<0.001) but higher haemoglobin (17.5 vs. 14.4 g/l, p<0.001) than lowlanders. Prevalence of elevated OBP was low at high altitude. Elevated ambulatory BP was much more frequent at both altitudes. Consequently there was a high prevalence of masked hypertension, which was a dominating high BP phenotype among highlanders. Main results are reported in the Table. The altitude of residence remained independently associated with elevated 24-hour BP (p<0.001) in a multiple logistic regression model including age, sex and BMI as covariates. Conclusions. Many individuals in Peru, especially highlanders, are exposed to BP-related risk, which cannot be captured by office measurements alone.