Ohnishi T, et al. - In this cohort study, researchers focused on the link between postdialysis potassium levels and all-cause mortality among 3967 participants on maintenance hemodialysis from the Dialysis Outcomes and Practice Patterns Study in Japan (2009–2012 and 2012–2015). They obtained repeated measurements of postdialysis serum potassium at 4-month intervals and used it as a time-varying variable. At baseline, the study sample aged 65±12 years (mean±SD). Of overall participants, 2552 (64%) were men, and 96% were treated with a dialysate potassium level of 2.0 to <2.5 mEq/L. The participants were observed over a median duration of 2.6 (interquartile range, 1.3–2.8) years, during which, deaths of 562 (14%) of 3967 participants and the overall mortality rate of 6.7 per 100 person-years were reported. Findings revealed a link between postdialysis hypokalemia and mortality, but this link was not independent of predialysis potassium.