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Research Project: Childhood Obesity Prevention

Location: Children's Nutrition Research Center

Title: Spot urine sodium-to-potassium ratio is a predictor of stroke

item AVERILL, MICHELLE - University Of Washington
item YOUNG, REBEKAH - US Department Of JUStice
item WOOD, ALEXIS - Children'S Nutrition Research Center (CNRC)
item KURLAK, EMILY - University Of Washington
item KRAMER, HOLLY - Loyola University
item STEFFEN, LYN - University Of Minnesota
item MCCLELLAND, ROBYN - University Of Washington
item DELANEY, JOSEPH - University Of Washington
item DREWNOWSKI, ADAM - University Of Washington

Submitted to: Stroke
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2018
Publication Date: 2/1/2019
Citation: Averill, M.M., Young, R.L., Wood, A.C., Kurlak, E.O., Kramer, H., Steffen, L., McClelland, R.L., Delaney, J.A., Drewnowski, A. 2019. Spot urine sodium-to-potassium ratio is a predictor of stroke. Stroke. 50(2):321-327.

Interpretive Summary: Dietary sodium reduction and a simultaneous increase in potassium intake are very important in reducing cardiovascular disease (CVD) risk and control blood pressure, a known modifiable risk factor for cardiovascular disease. Currently, not only dietary sodium intakes are too high and potassium levels too low, but their unhealthy consumption has remained stable over time. Thus, the need to address these dietary components continues to be needed. Most studies that measure sodium and potassium intake rely on self-reported measures, which are have many limitations, such as poor recall and inaccurate or incomplete data. A good way of measuring these dietary components while addressing these limitations is urinary excretion. This study assessed whether urinary sodium-to-potassium ratio, obtained from spot urines, predicted the risk of subsequent major CVD in a diverse and multiethnic (European-, Asian-, African- and Hispanic-American) American population. A total of 6814 adults participated in this prospective study, MESA (Multi-Ethnic Study of Atherosclerosis), longitudinally. At the beginning of the study, all participants were free of clinical cardiovascular disease. Results of this study show that over eleven years of follow-up a sodium-to-potassium ratio over 1 is associated with a greater risk of stroke in racially and ethnically diverse adult Americans. Additionally, it may also be associated with a broader range of CVD. These results have important clinical implications as the collection of spot urines is inexpensive and already part of routine clinical care. Finally, an intermediate target (sodium-to-potassium ratio of less than 1) could be a vital target of future public health interventions.

Technical Abstract: Dietary sodium reduction with concurrent increase in potassium intake is a current public health priority to reduce risk of cardiovascular events. This study explored associations between the spot urine sodium-to-potassium ratio and cardiovascular events in the MESA (Multi-Ethnic Study of Atherosclerosis) longitudinal cohort. The MESA is a prospective cohort study of 6814 adults from 4 ethnic groups (European-, Asian-, African- and Hispanic-American) with a mean age of 62 (+/-10.2) years and an average of 11.7 (+/- 2.2) years of follow-up. Participants were free of clinical cardiovascular disease at baseline. Spot urine sodium and potassium excretion, as a marker of dietary intake, was collected at baseline. The impact of urinary sodium-to-potassium ratio on adjudicated cardiovascular events was assessed using Cox proportional hazards models. Only 39% of MESA participants had a urinary sodium-to-potassium ratio <=1, and these participants experienced only 74 of the 236 strokes. A sodium-to-potassium ratio >1 was associated with a hazard ratio of 1.47 (95% CI,1.07–2.00) for risk of stroke, adjusting for age, sex, race, cardiovascular risk factors, socio-demographic characteristics, body size, and kidney function. The spot urine sodium-to-potassium ratio (measurable in routine care) is associated with stroke. A urine sodium-to-potassium ratio of <=1, may be related to a clinically relevant reduction in stroke risk and is a feasible target for health interventions.