Kenichi Tanaka1,2, Hirotaka Saito3, Tsuyoshi Iwasaki3, Akira Oda3, Shuhei Watanabe3, Makoto Kanno3,4, Hiroshi Kimura3, Michio Shimabukuro4,5, Koichi Asahi4,6, Tsuyoshi Watanabe4, Junichiro J Kazama3,4. 1. Department of Nephrology and Hypertension, Fukushima Medical University, 1, Hikarigaoka, Fukushima City, Fukushima, 960-1295, Japan. kennichi@fmu.ac.jp. 2. Department of Chronic Kidney Disease Initiatives, Fukushima Medical University, Fukushima, Japan. kennichi@fmu.ac.jp. 3. Department of Nephrology and Hypertension, Fukushima Medical University, 1, Hikarigaoka, Fukushima City, Fukushima, 960-1295, Japan. 4. Department of Chronic Kidney Disease Initiatives, Fukushima Medical University, Fukushima, Japan. 5. Department of Diabetes, Endocrinology and Metabolism, Fukushima Medical University, Fukushima, Japan. 6. Division of Nephrology and Hypertension, Iwate Medical University, Yahaba, Japan.
Abstract
BACKGROUND: Serum potassium disorders, commonly observed in chronic kidney disease (CKD), are reportedly associated with higher mortality, but their impact on renal outcomes is still controversial. METHODS: The present study used the longitudinal data of the Fukushima CKD cohort study to investigate the relationships between hypokalemia and hyperkalemia and adverse outcomes such as renal outcomes and all-cause mortality in Japanese patients with non-dialysis-dependent CKD. The study involved 1330 CKD patients followed-up for 2.8 years. The primary endpoint of the present study was a kidney event, defined as a combination of doubling of baseline serum creatinine and end-stage kidney disease. RESULTS: Hyperkalemia (≥ 5.0 mmol/L) was noted in 10.6% and hypokalemia (< 4.0 mmol/L) in 16.4% of the study population. Significant U-shaped associations were observed between potassium levels and both kidney events and all-cause mortality on univariate Cox regression analyses. After adjustment for covariates, both hypokalemia and hyperkalemia were significantly associated with an increased risk of kidney events, with the lowest risk at a serum potassium of 4.0-4.4 mmol/L. Compared with a reference level of 4.0-4.4 mmol/L, the adjusted hazard ratio for kidney events was 2.49 (1.33-4.66) for serum potassium < 4.0 mmol/L, 1.72 (1.00-2.96) for 4.5-4.9 mmol/L, and 2.16 (1.15-4.06) for ≥ 5.0 mmol/L. There was no significant association between serum potassium levels and mortality after multivariate adjustment. CONCLUSION: Hypokalemia and hyperkalemia were associated with an increased risk of CKD progression, but not with mortality in Japanese patients with non-dialysis-dependent CKD.
BACKGROUND: Serum potassium disorders, commonly observed in chronic kidney disease (CKD), are reportedly associated with higher mortality, but their impact on renal outcomes is still controversial. METHODS: The present study used the longitudinal data of the Fukushima CKD cohort study to investigate the relationships between hypokalemia and hyperkalemia and adverse outcomes such as renal outcomes and all-cause mortality in Japanese patients with non-dialysis-dependent CKD. The study involved 1330 CKD patients followed-up for 2.8 years. The primary endpoint of the present study was a kidney event, defined as a combination of doubling of baseline serum creatinine and end-stage kidney disease. RESULTS:Hyperkalemia (≥ 5.0 mmol/L) was noted in 10.6% and hypokalemia (< 4.0 mmol/L) in 16.4% of the study population. Significant U-shaped associations were observed between potassium levels and both kidney events and all-cause mortality on univariate Cox regression analyses. After adjustment for covariates, both hypokalemia and hyperkalemia were significantly associated with an increased risk of kidney events, with the lowest risk at a serum potassium of 4.0-4.4 mmol/L. Compared with a reference level of 4.0-4.4 mmol/L, the adjusted hazard ratio for kidney events was 2.49 (1.33-4.66) for serum potassium < 4.0 mmol/L, 1.72 (1.00-2.96) for 4.5-4.9 mmol/L, and 2.16 (1.15-4.06) for ≥ 5.0 mmol/L. There was no significant association between serum potassium levels and mortality after multivariate adjustment. CONCLUSION:Hypokalemia and hyperkalemia were associated with an increased risk of CKD progression, but not with mortality in Japanese patients with non-dialysis-dependent CKD.