Association of socioeconomic and lifestyle variables with 24-hour blood pressure in peruvian lowlanders and highlanders

Abstract Aim Previous evidence suggested the presence of difference in blood pressure (BP) levels and hypertension prevalence between residents of low and high altitudes in South America. HIGHCARE-ANDES is a population study aimed at assessing these differences by means of 24-hour ambulatory BP monitoring. The present analysis addressed the presence of differences in socioeconomic and lifestyle factors between lowlanders and highlanders participating in this study and their association with BP levels. Methods Study participants (adults permanently residing at either low or high altitude) were recruited by sex- and age-stratified random multistage cluster sampling from the general population of urban areas at different altitudes in Peru (Lima, <500 m above sea level, Huancayo 3287 m, Juliaca 3824 m, Cerro de Pasco 4330 m). Information on socioeconomic and lifestyle factors was obtained from WHO-STEPS 3.0ES questionnaire except physical activity which was estimated based on IPAQ questionnaire. Results The study included 206 lowlanders (52% female) and 595 highlanders (50% female). The highlanders were slightly younger (median[IQR] 45 [34-57] years vs 47 [38-60], p=0.013), had lower BMI (26.33 [23.77-29.41] vs 27.98 [25.35-31.59] kg/m2, p<0.0001) and 24-hour systolic BP (118.55 [110.29-127.66] vs. 124.97 [115.62-138.5] mmHg, p<0.0001). Socioeconomic and lifestyle variables are reported in the Table. Compared with lowlanders, highlanders had a lower prevalence of former smokers and current drinkers, higher self-reported salt intake, slightly higher degree of physical activity and higher consumption of vegetables. In multivariable analysis adjusting for age, sex, BMI, socioeconomic and lifestyle variables the difference between highlanders and lowlanders in 24-hour SBP remained significant (mean adjusted difference [SE] 5.18 [2.1] mmHg, p=0.013). Age, sex and BMI were independently associated with 24-hour SBP while socioeconomic and lifestyle factors were not. Conclusions In the general population of Peru, the residence at high altitude is associated with overall healthier lifestyle compared to the lowlanders. This difference, however, does not explain the lower BP values found among highlanders suggesting that other factors are involved, possibly the hypobaric hypoxia itself.