Measured sodium excretion is associated with cardiovascular outcomes in non-dialysis CKD patients: results from the KNOW-CKD study

Seong Cheol Kang; Minjung Kang; Hyunjin Ryu; Seonmi Kim; Ji Hye Kim; Eunjeong Kang; Yujin Jeong; Jayoun Kim; Yong-Soo Kim; Soo Wan Kim; Yeong Hoon Kim; Kook-Hwan Oh

doi:10.3389/fneph.2023.1236177

Measured sodium excretion is associated with cardiovascular outcomes in non-dialysis CKD patients: results from the KNOW-CKD study

Front Nephrol. 2023 Aug 25:3:1236177. doi: 10.3389/fneph.2023.1236177. eCollection 2023.

Authors

Seong Cheol Kang¹, Minjung Kang², Hyunjin Ryu², Seonmi Kim², Ji Hye Kim³, Eunjeong Kang^{2

4}, Yujin Jeong⁵, Jayoun Kim⁶, Yong-Soo Kim⁷, Soo Wan Kim⁸, Yeong Hoon Kim⁹, Kook-Hwan Oh^{10

11}

Affiliations

¹ Department of Medical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea.
² Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
³ Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, Republic of Korea.
⁴ Transplantation Center, Seoul National University Hospital, Seoul, Republic of Korea.
⁵ Department of Biostatistics, Korea University College of Medicine, Seoul, Republic of Korea.
⁶ Medical Research Collaborating Center, Seoul National University Hospital, Seoul, Republic of Korea.
⁷ Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
⁸ Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea.
⁹ Department of Internal Medicine, Inje University Busan Paik Hospital, Busan, Republic of Korea.
¹⁰ Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
¹¹ Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.

Abstract

Background: There are insufficient studies on the effect of dietary salt intake on cardiovascular (CV) outcomes in chronic kidney disease (CKD) patients, and there is no consensus on the sodium (Na) intake level that increases the risk of CV disease in CKD patients. Therefore, we investigated the association between dietary salt intake and CV outcomes in CKD patients.

Methods: In the Korean cohort study for Outcome in patients with CKD (KNOW-CKD), 1,937 patients were eligible for the study, and their dietary Na intake was estimated using measured 24h urinary Na excretion. The primary outcome was a composite of CV events and/or all-cause death. The secondary outcome was a major adverse cardiac event (MACE).

Results: Among 1,937 subjects, there were 205 (10.5%) events for the composite outcome and 110 (5.6%) events for MACE. Compared to the reference group (urinary Na excretion< 2.0g/day), the group with the highest measured 24h urinary Na excretion (urinary Na excretion ≥ 8.0g/day) was associated with increased risk of both the composite outcome (hazard ratio 3.29 [95% confidence interval 1.00-10.81]; P = 0.049) and MACE (hazard ratio 6.28 [95% confidence interval 1.45-27.20]; P = 0.013) in a cause-specific hazard model. Subgroup analysis also showed a pronounced association between dietary salt intake and the composite outcome in subgroups of patients with abdominal obesity, female, lower estimated glomerular filtration rate (< 60 ml/min per 1.73m²), no overt proteinuria, or a lower urinary potassium-to-creatinine ratio (< 46 mmol/g).

Conclusion: A high-salt diet is associated with CV outcomes in non-dialysis CKD patients.

Keywords: all-cause mortality; cardiovascular outcome; chronic kidney disease; dietary salt intake; major adverse cardiac event.

Grants and funding

This study was supported by funds from the research program of the Korea Disease Control and Prevention Agency (2011E3300300, 2012E3301100, 2013E3301600, 2013E3301601, 2013E3301602, 2016E3300200, 2016E3300201, 2016E3300202, 2019E320100, 2019E320101, 2019E320102, 2022-11-007).