Urinary Sodium and Potassium, and Risk of Ischemic and Hemorrhagic Stroke (INTERSTROKE): A Case-Control Study

• Published in: American Journal of Hypertension
• Main Author: Judge C.; O'Donnell M.J.; Hankey G.J.; Rangarajan S.; Chin S.L.; Rao-Melacini P.; Ferguson J.; Smyth A.; Xavier D.; Lisheng L.; Zhang H.; Lopez-Jaramillo P.; Damasceno A.; Langhorne P.; Rosengren A.; Dans A.L.; Elsayed A.; Avezum A.; Mondo C.; Ryglewicz D.; Czlonkowska A.; Pogosova N.; Weimar C.; Diaz R.; Yusoff K.; Yusufali A.; Oguz A.; Wang X.; Lanas F.; Ogah O.S.; Ogunniyi A.; Iversen H.K.; Malaga G.; Rumboldt Z.; Oveisgharan S.; Al Hussain F.; Yusuf S.
• Format: Article
• Language: English
• Published: Oxford University Press 2021
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105696305&doi=10.1093%2fajh%2fhpaa176&partnerID=40&md5=e86042b7632cc34f57642e60426c162b
• ISSN: 8957061
• DOI: 10.1093/ajh/hpaa176

Although low sodium intake (<2 g/day) and high potassium intake (>3.5 g/day) are proposed as public health interventions to reduce stroke risk, there is uncertainty about the benefit and feasibility of this combined recommendation on prevention of stroke. METHODS: We obtained random urine samples from 9,275 cases of acute first stroke and 9,726 matched controls from 27 countries and estimated the 24-hour sodium and potassium excretion, a surrogate for intake, using the Tanaka formula. Using multivariable conditional logistic regression, we determined the associations of estimated 24-hour urinary sodium and potassium excretion with stroke and its subtypes. RESULTS: Compared with an estimated urinary sodium excretion of 2.8-3.5 g/day (reference), higher (>4.26 g/day) (odds ratio [OR] 1.81; 95% confidence interval [CI], 1.65-2.00) and lower (<2.8 g/day) sodium excretion (OR 1.39; 95% CI, 1.26-1.53) were significantly associated with increased risk of stroke. The stroke risk associated with the highest quartile of sodium intake (sodium excretion >4.26 g/day) was significantly greater (P < 0.001) for intracerebral hemorrhage (ICH) (OR 2.38; 95% CI, 1.93-2.92) than for ischemic stroke (OR 1.67; 95% CI, 1.50-1.87). Urinary potassium was inversely and linearly associated with risk of stroke, and stronger for ischemic stroke than ICH (P = 0.026). In an analysis of combined sodium and potassium excretion, the combination of high potassium intake (>1.58 g/day) and moderate sodium intake (2.8-3.5 g/day) was associated with the lowest risk of stroke. CONCLUSIONS: The association of sodium intake and stroke is J-shaped, with high sodium intake a stronger risk factor for ICH than ischemic stroke. Our data suggest that moderate sodium intake - rather than low sodium intake - combined with high potassium intake may be associated with the lowest risk of stroke and expected to be a more feasible combined dietary target. © 2020 The Author(s) 2020. Published by Oxford University Press on behalf of American Journal of Hypertension, Ltd.