Race, Serum Potassium, and Associations With ESRD and Mortality

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e231">Background</h5> <p id="P1">Recent studies suggest that potassium levels may differ by race. The basis for these differences and whether associations between potassium levels and adverse outcomes differ by race is unknown. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e236">Study Design</h5> <p id="P2">Observational study.</p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e241">Setting &amp; Participants</h5> <p id="P3">Associations between race and potassium as well as the interaction of race and potassium with outcomes were investigated in the Racial and Cardiovascular Risk Anomalies in Chronic Kidney Disease (RCAV) study, a cohort of US veterans (N=2,662,462). Associations between African ancestry and potassium were investigated in African Americans in the Atherosclerosis Risk in Communities (ARIC) Study (N=3,450). </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e246">Predictors</h5> <p id="P4">Race (African American vs non-African American) for cross-sectional analysis; serum potassium as a continuous variable (for longitudinal analysis). </p> </div><div class="section"> <a class="named-anchor" id="S5"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e251">Outcomes</h5> <p id="P5">For cross-sectional analysis: potassium level; for longitudinal analysis: mortality and end-stage renal disease (ESRD) via linkage with the Veterans Affairs Vital Status File and the US Renal Data System. </p> </div><div class="section"> <a class="named-anchor" id="S6"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e256">Results</h5> <p id="P6">The RCAV cohort was 18% African American (N=470,985). Potassium levels were, on average, 0.162 mmol/L lower in African Americans compared to non-African Americans, with differences persisting after adjustment for demographics, comorbidities, and potassium-altering medication use. In the ARIC study, higher African ancestry was related to lower potassium levels (-0.027 mmol/L per each 10% African ancestry). In both race groups, higher and lower levels of potassium were associated with mortality. Compared to a potassium of 4.2 mmol/L, the mortality risk associated with lower levels of potassium was lesser in African Americans vs non-African Americans, whereas mortality risk associated with higher levels was slightly greater. For ESRD, risk-relationships were weaker, with no difference by race. </p> </div><div class="section"> <a class="named-anchor" id="S7"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e261">Limitations</h5> <p id="P7">No data on potassium intake.</p> </div><div class="section"> <a class="named-anchor" id="S8"> <!-- named anchor --> </a> <h5 class="section-title" id="d6408493e266">Conclusions</h5> <p id="P8">African Americans had slightly lower serum potassium levels than non-African Americans. Consistent associations between potassium and percent African ancestry may suggest a genetic component to these differences. Higher and lower serum potassium levels were associated with mortality in both racial groups. </p> </div>