MO465PROGNOSTIC IMPLICATION OF URINARY POTASSIUM EXCRETION IN PATIENTS WITH CHRONIC KIDNEY DISEASE

Background and Aims Plasma potassium levels are impacted by decreased kidney function and are known to be associated with increased mortality, adverse cardiovascular events and adverse kidney events. However, the prognostic implication of urinary potassium is unclear. Method We conducted an observational study of 1102 patients with chronic kidney disease (CKD) who were hospitalized between 2010 and 2018. The expected primary outcomes were all-cause mortality, adverse cardiovascular events and CKD progression. CKD progression was defined as a 30% increase in serum creatinine, the initiation of maintenance dialysis or the need for kidney transplantation. The Cox proportional hazards model was used to analyse the association between urinary potassium excretion and adverse clinical outcomes after adjustment for potential confounders. Results At baseline, 66% of the patients were men, with a median age of 72 years (interquartile range or IQR, 64–79 years); 61% of the patients were diabetic, and 54% of them were hypertensive. The median values for estimated glomerular filtration rate (eGFR) was 12 mL/min/1.73m2 (IQR, 8–18), serum potassium 4.5 mmol/L (IQR, 4.1–5.1) and urinary potassium/creatinine ratio (UK/Cr) 27 mmol/gCr (IQR, 20–38). Over a median follow-up period of 2.6 years (IQR 0.2–4.5), the number of all-cause deaths was 87. There were 171 cases of cardiovascular events and 860 cases of CKD progression. After adjusting for the eGFR, serum potassium level, proteinuria, renin–angiotensin system inhibitors, diuretics and other potential confounders, UK/Cr was found to be neither significantly associated with all-cause mortality nor with adverse cardiovascular events. However, a low UK/Cr was associated with an increased risk of CKD progression (adjusted hazard ratio [95% confidence interval] for the first, second and third quartiles, compared with the fourth quartile, were as follows: 2.09 [1.43-3.06], 1.33 [0.96-1.86] and 1.05 [0.75-1.46]) Conclusion A low UK/Cr might be an independent risk factor for poor renal outcome.