Association between blood pressure control in hypertension and urine sodium to potassium ratio: From the Korea National Health and Nutrition Examination Survey (2016-2021)

Background Hypertension (HTN) is linked to an enhanced risk of chronic kidney disease and cardiovascular disease. While sodium and potassium intake affect blood pressure (BP) control, the urine sodium-to-potassium (Na/K) ratio, which reflects dietary balance and renal regulation of these electrolytes, could be associated with BP. This study aimed to evaluate the independent association between urine Na/K and uncontrolled HTN. Methods Data were collected from the Korea National Health and Nutrition Examination Survey from 2016 to 2021. A total of 5,770 participants diagnosed with HTN were enrolled in this study. Uncontrolled HTN was characterized by a systolic blood pressure (SBP) >= 140 mmHg or diastolic blood pressure (DBP) >= 90 mmHg. Logistic regression analysis was used to assess the relationship between urine Na/K and the risk of uncontrolled HTN. Results The urine Na/K was positively correlated with both SBP and mean arterial pressure. Higher urine Na/K was significantly associated with an increased risk of uncontrolled HTN using both continuous (odds ratio [95% confidence interval] 1.13 [1.09-1.16], P <0.01]) and across quartile values (with Q1 as a reference; Q2: 1.26 [1.06-1.49], P = 0.01; Q3: 1.50 [1.27-1.78], P <0.01; Q4: 1.85 [1.55-2.17], P < 0.01). The subgroup analysis also showed that higher urine Na/K were significantly related to the risk of uncontrolled HTN in the presence of proteinuria or CKD. Conclusion Urine Na/K ratio is independently associated with uncontrolled HTN in the general population and in patients with CKD. Our findings suggest that monitoring the urine Na/K could serve as an effective tool for identifying subjects at risk of uncontrolled HTN.