Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort

Taehee Kim, Connie M. Rhee, Elani Streja, Melissa Soohoo, Yoshitsugu Obi, Jason A. Chou, Amanda R. Tortorici, Vanessa A. Ravel, Csaba Kovesdy, Kamyar Kalantar-Zadeh

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Abstract

Background: Hyperkalemia is observed in chronic kidney disease patients and may be a risk factor for life-threatening arrhythmias and death. Race/ethnicity may be important modifiers of the potassium-mortality relationship in maintenance hemodialysis (MHD) patients given that potassium intake and excretion vary among minorities. Methods: We examined racial/ethnic differences in baseline serum potassium levels and all-cause and cardiovascular mortality using Cox proportional hazard models and restricted cubic splines in a cohort of 102,241 incident MHD patients. Serum potassium was categorized into 6 groups: ≤3.6, >3.6 to ≤4.0, >4.0 to ≤4.5 (reference), >4.5 to ≤5.0, >5.0 to ≤5.5, and >5.5 mEq/L. Models were adjusted for case-mix and malnutrition-inflammation cachexia syndrome (MICS) covariates. Results: The cohort was composed of 50% whites, 34% African-Americans, and 16% Hispanics. Hispanics tended to have the highest baseline serum potassium levels (mean ± SD: 4.58 ± 0.55 mEq/L). Patients in our cohort were followed for a median of 1.3 years (interquartile range 0.6-2.5). In our cohort, associations between higher potassium (>5.5 mEq/L) and higher mortality risk were observed in African-American and whites, but not Hispanic patients in models adjusted for case-mix and MICS covariates. While in Hispanics only, lower serum potassium (<3.6 mEq/L) levels were associated with higher mortality risk. Similar trends were observed for cardiovascular mortality. Conclusions: Higher potassium levels were associated with higher mortality risk in white and African-American MHD patients, whereas lower potassium levels were associated with higher death risk in Hispanics. Further studies are needed to determine the underlying mechanisms for the differential association between potassium and mortality across race/ethnicity.

Original languageEnglish (US)
Pages (from-to)509-521
Number of pages13
JournalAmerican Journal of Nephrology
Volume45
Issue number6
DOIs
StatePublished - Jun 1 2017

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Renal Dialysis
Potassium
Mortality
Serum
Hispanic Americans
African Americans
Cachexia
Diagnosis-Related Groups
Malnutrition
Inflammation
Hyperkalemia
Chronic Renal Insufficiency
Proportional Hazards Models
Cardiac Arrhythmias
Maintenance

All Science Journal Classification (ASJC) codes

  • Nephrology

Cite this

Kim, T., Rhee, C. M., Streja, E., Soohoo, M., Obi, Y., Chou, J. A., ... Kalantar-Zadeh, K. (2017). Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort. American Journal of Nephrology, 45(6), 509-521. https://doi.org/10.1159/000475997

Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort. / Kim, Taehee; Rhee, Connie M.; Streja, Elani; Soohoo, Melissa; Obi, Yoshitsugu; Chou, Jason A.; Tortorici, Amanda R.; Ravel, Vanessa A.; Kovesdy, Csaba; Kalantar-Zadeh, Kamyar.

In: American Journal of Nephrology, Vol. 45, No. 6, 01.06.2017, p. 509-521.

Research output: Contribution to journalArticle

Kim, T, Rhee, CM, Streja, E, Soohoo, M, Obi, Y, Chou, JA, Tortorici, AR, Ravel, VA, Kovesdy, C & Kalantar-Zadeh, K 2017, 'Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort', American Journal of Nephrology, vol. 45, no. 6, pp. 509-521. https://doi.org/10.1159/000475997
Kim, Taehee ; Rhee, Connie M. ; Streja, Elani ; Soohoo, Melissa ; Obi, Yoshitsugu ; Chou, Jason A. ; Tortorici, Amanda R. ; Ravel, Vanessa A. ; Kovesdy, Csaba ; Kalantar-Zadeh, Kamyar. / Racial and Ethnic Differences in Mortality Associated with Serum Potassium in a Large Hemodialysis Cohort. In: American Journal of Nephrology. 2017 ; Vol. 45, No. 6. pp. 509-521.
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abstract = "Background: Hyperkalemia is observed in chronic kidney disease patients and may be a risk factor for life-threatening arrhythmias and death. Race/ethnicity may be important modifiers of the potassium-mortality relationship in maintenance hemodialysis (MHD) patients given that potassium intake and excretion vary among minorities. Methods: We examined racial/ethnic differences in baseline serum potassium levels and all-cause and cardiovascular mortality using Cox proportional hazard models and restricted cubic splines in a cohort of 102,241 incident MHD patients. Serum potassium was categorized into 6 groups: ≤3.6, >3.6 to ≤4.0, >4.0 to ≤4.5 (reference), >4.5 to ≤5.0, >5.0 to ≤5.5, and >5.5 mEq/L. Models were adjusted for case-mix and malnutrition-inflammation cachexia syndrome (MICS) covariates. Results: The cohort was composed of 50{\%} whites, 34{\%} African-Americans, and 16{\%} Hispanics. Hispanics tended to have the highest baseline serum potassium levels (mean ± SD: 4.58 ± 0.55 mEq/L). Patients in our cohort were followed for a median of 1.3 years (interquartile range 0.6-2.5). In our cohort, associations between higher potassium (>5.5 mEq/L) and higher mortality risk were observed in African-American and whites, but not Hispanic patients in models adjusted for case-mix and MICS covariates. While in Hispanics only, lower serum potassium (<3.6 mEq/L) levels were associated with higher mortality risk. Similar trends were observed for cardiovascular mortality. Conclusions: Higher potassium levels were associated with higher mortality risk in white and African-American MHD patients, whereas lower potassium levels were associated with higher death risk in Hispanics. Further studies are needed to determine the underlying mechanisms for the differential association between potassium and mortality across race/ethnicity.",
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AU - Kim, Taehee

AU - Rhee, Connie M.

AU - Streja, Elani

AU - Soohoo, Melissa

AU - Obi, Yoshitsugu

AU - Chou, Jason A.

AU - Tortorici, Amanda R.

AU - Ravel, Vanessa A.

AU - Kovesdy, Csaba

AU - Kalantar-Zadeh, Kamyar

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Y1 - 2017/6/1

N2 - Background: Hyperkalemia is observed in chronic kidney disease patients and may be a risk factor for life-threatening arrhythmias and death. Race/ethnicity may be important modifiers of the potassium-mortality relationship in maintenance hemodialysis (MHD) patients given that potassium intake and excretion vary among minorities. Methods: We examined racial/ethnic differences in baseline serum potassium levels and all-cause and cardiovascular mortality using Cox proportional hazard models and restricted cubic splines in a cohort of 102,241 incident MHD patients. Serum potassium was categorized into 6 groups: ≤3.6, >3.6 to ≤4.0, >4.0 to ≤4.5 (reference), >4.5 to ≤5.0, >5.0 to ≤5.5, and >5.5 mEq/L. Models were adjusted for case-mix and malnutrition-inflammation cachexia syndrome (MICS) covariates. Results: The cohort was composed of 50% whites, 34% African-Americans, and 16% Hispanics. Hispanics tended to have the highest baseline serum potassium levels (mean ± SD: 4.58 ± 0.55 mEq/L). Patients in our cohort were followed for a median of 1.3 years (interquartile range 0.6-2.5). In our cohort, associations between higher potassium (>5.5 mEq/L) and higher mortality risk were observed in African-American and whites, but not Hispanic patients in models adjusted for case-mix and MICS covariates. While in Hispanics only, lower serum potassium (<3.6 mEq/L) levels were associated with higher mortality risk. Similar trends were observed for cardiovascular mortality. Conclusions: Higher potassium levels were associated with higher mortality risk in white and African-American MHD patients, whereas lower potassium levels were associated with higher death risk in Hispanics. Further studies are needed to determine the underlying mechanisms for the differential association between potassium and mortality across race/ethnicity.

AB - Background: Hyperkalemia is observed in chronic kidney disease patients and may be a risk factor for life-threatening arrhythmias and death. Race/ethnicity may be important modifiers of the potassium-mortality relationship in maintenance hemodialysis (MHD) patients given that potassium intake and excretion vary among minorities. Methods: We examined racial/ethnic differences in baseline serum potassium levels and all-cause and cardiovascular mortality using Cox proportional hazard models and restricted cubic splines in a cohort of 102,241 incident MHD patients. Serum potassium was categorized into 6 groups: ≤3.6, >3.6 to ≤4.0, >4.0 to ≤4.5 (reference), >4.5 to ≤5.0, >5.0 to ≤5.5, and >5.5 mEq/L. Models were adjusted for case-mix and malnutrition-inflammation cachexia syndrome (MICS) covariates. Results: The cohort was composed of 50% whites, 34% African-Americans, and 16% Hispanics. Hispanics tended to have the highest baseline serum potassium levels (mean ± SD: 4.58 ± 0.55 mEq/L). Patients in our cohort were followed for a median of 1.3 years (interquartile range 0.6-2.5). In our cohort, associations between higher potassium (>5.5 mEq/L) and higher mortality risk were observed in African-American and whites, but not Hispanic patients in models adjusted for case-mix and MICS covariates. While in Hispanics only, lower serum potassium (<3.6 mEq/L) levels were associated with higher mortality risk. Similar trends were observed for cardiovascular mortality. Conclusions: Higher potassium levels were associated with higher mortality risk in white and African-American MHD patients, whereas lower potassium levels were associated with higher death risk in Hispanics. Further studies are needed to determine the underlying mechanisms for the differential association between potassium and mortality across race/ethnicity.

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