Sociodemographic patterns of urine sodium excretion and its association with hypertension in Chile: a cross-sectional analysis

Abstract

Objective: The aim of the study was to determine the main factors (sociodemographic, anthropometric, lifestyle and health status) associated with high Na excretion in a representative population of Chile.

Design: Na excretion (g/d), a valid marker of Na intake, was determined by urine analysis and Tanaka's formulas. Blood pressure was measured by trained staff and derived from the mean of three readings recorded after 15 min rest. The associations of Na excretion with blood pressure and the primary correlates of high Na excretion were determined using logistic regression.

Setting: Chileans aged ≥15 years.ParticipantsParticipants (n 2913) from the Chilean National Health Survey 2009-2010.

Results: Individuals aged 25 years or over, those who were obese and those who had hypertension, diabetes or metabolic syndrome were more likely to have higher Na excretion. The odds for hypertension increased by 10·2 % per 0·4 g/d increment in Na excretion (OR=1·10; 95 % CI 1·06, 1·14; P < 0·0001). These findings were independent of major confounding factors.

Conclusions: Age, sex, adiposity, sitting behaviours and existing co-morbidities such as diabetes were associated with higher Na excretion levels in the Chilean population. These findings could help policy makers to implement public health strategies tailored towards individuals who are more likely to consume high levels of dietary salt.

Keywords: Hypertension; Lifestyle; Risk factors; Sodium excretion.

Fig. 1

Asociation of sodium excretion with (a) systolic blood pressure (SBP), (b) diastolic blood pressure (DBP) and (c) mean arterial blood pressure (MAP) in Chileans aged ≥15 years (n 2913) from the Chilean National Health Survey 2009–2010. Data are presented as means with their 95 % CI indicated by vertical bars; indicates the population average blood pressure, indicates the population average Na excretion. Analyses were adjusted age, sex, area of residence (rural, urban), city of residence, education level, smoking, sedentary behaviour, total physical activity and BMI category. Participants who were on blood pressure-lowering medication were removed from this analysis (n 694)

Fig. 2

Association between sodium excretion and hypertension in Chileans aged ≥15 years (n 2913) from the Chilean National Health Survey 2009–2010. Data are presented as OR (———) and their 95 % CI (); denotes OR = 1. (a) Model 0, unadjusted; (b) Model 1, adjusted for age, sex, area of residence (rural, urban), city of residence, education level and blood pressure treatment; (c) Model 2, adjusted for Model 1 plus smoking, sedentary behaviour, total physical activity and BMI category

Fig. 3

Correlates of high sodium excretion in Chileans aged ≥15 years (n 2913) from the Chilean National Health Survey 2009–2010. Data are presented as OR (■) with their 95 % CI represented by horizontal bars. Low sodium excretion (<3·6 g/d) was used as a reference category (Ref.), therefore OR above 1 indicates that individuals were more likely to have higher sodium intake. Analyses were adjusted for age, sex, area of residence (rural, urban), city of residence, education level, smoking, sedentary behaviour, total physical activity and BMI category, except when these variables were used as main exposures