Factors associated with urinary sodium/potassium ratio in participants in the ELSA-Brazil study

This study aimed to identify sociodemographic factors associated with high estimated sodium/potassium ratio. A total of 15,105 participants were assessed, from 35 to 74 years of age, from a cohort of public employees (ELSA-Brazil). Socioeconomic data were collected with a questionnaire, and 12-hour nighttime urine samples were collected to estimate sodium and potassium intake. Sodium/potassium ratio was calculated in mmol/L and divided into tertiles: 1st tertile, corresponding to "low"; 2nd tertile for "medium"; and 3rd tertile for "high" sodium/potassium ratio. The proportions and means were compared according to the classification of tertiles in the sodium/potassium ratio, using chi-square test and analysis of variance (ANOVA). Crude and adjusted multinomial logistic regression models were tested, with the 1st tertile as the reference. Factors associated with sodium/potassium ratio were: male sex (OR = 1.78; 95%CI: 1.60-1.98); age 35 to 44 years (OR = 1.71; 95%CI: 1.33-2.19); incomplete elementary schooling (OR = 2.38; 95%CI: 1.78-3.18); and lower income (OR = 1.47; 95%CI: 1.26-1.73). Men, younger individuals, and those with less schooling and income showed higher mean sodium/potassium ratio.