Association of Low Serum Potassium Levels and Risk for All-Cause Mortality in Patients With Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Dyskalemia is a risk factor for mortality in patients without CKD, but the effect of hypokalemia in patients with CKD remains uncertain. PubMed, Embase, Cochrane, and Ovid databases were searched from inception to December 31, 2017 for studies that reported all-cause and cardiovascular mortality or events in patients with CKD (any stage). Pooled hazard ratios (HR) and corresponding 95% CI were calculated. A total of 11 clinical studies enrolling 57 234 subjects with CKD were included in the meta-analysis. Compared with control serum potassium (SK) levels, low SK (SK <4.0 mEq/L) was associated with higher risk of all-cause mortality in a random-effects model (HR = 1.57; 95% CI: 1.25-1.97). Moderate low SK (<3.5 mEq/L) increased risk of all-cause mortality by 105%. Mild low SK (3.5 similar to 4.0 mEq/L) also increased all-cause mortality risk (HR = 1.18, 95% CI: 1.11-1.26). Low SK was also associated with increased cardiovascular mortality (HR = 1.40, 95% CI: 1.22-1.62) and ESRD risk (HR = 1.35, 95% CI: 1.18-1.54). SK <4.0 mEq/L was associated with higher mortality risk in CKD patients, especially in those with SK <3.5 mEq/L. Additional prospective studies will be necessary to explore this relationship, as well as whether correcting hypokalemia decreases mortality in patients with CKD.