Multivariable-adjusted restricted cubic spline plots of (a) the hazard ratios (HR) for all-cause mortality according to post-dialysis serum sodium concentration (SNa)– pre-dialysis SNa (ΔSNa). Multivariable-adjusted restricted cubic spline plots of the odds ratios (OR) for (b) cerebral infarction and (c) lower limb amputation according to ΔSNa. The solid line represents the HR and OR, and the dotted line represents the 95% confidence interval. The multivariable-adjusted model (a) Cox model and (b) logistic model was adjusted for age, sex, duration of HD, length of an HD session, dialysate sodium, history of cardiovascular disease (CVD), Hb, Alb, SNa, Ca, P, T-Chol, Kt/V, CRP, nPCR, and ΔBW%. Alb, serum albumin; BW, body weight; Ca, calcium; CRP, C-reactive protein; Hb, hemoglobin; HD, hemodialysis; P, phosphate; nPCR, normal protein catabolic rate; T.Chol., total cholesterol.