(a–d). Association of pre-dialysis SBP and adjusted all-cause mortality risk stratified by subgroup using Model-TV-Lag. All models adjusted for age, sex, Black race, serum albumin concentration, vintage, modified ICED score, diabetes, residual kidney function and randomized intervention group, unless stratified by that variable. Error bars indicate 95% confidence intervals. SBP, systolic blood pressure; Model-TV-Lag, SBP as time-varying variable + 3-month lag. P-values for interaction of SBP2 with (a) age = 0.31 (b) sex = 0.99 (c) diabetes = 0.40 (d) Black race = 0.34.