Standard Kt/V thresholds to accurately predict single-pool Kt/V targets for children receiving thrice-weekly maintenance haemodialysis

Abstract

Urea standard Kt/V (stdKt/V) provides a tool to normalize weekly small solute clearance for patients dialysed at various intervals, but it has not been studied in the paediatric haemodialysis (HD) population. Using retrospective monthly adequacy data from children with end-stage renal disease receiving chronic thrice-weekly haemodialysis (n = 30), single-pool (spKt/V), equilibrated (eKt/V) and standard Kt/V (stdKt/V) were calculated for each individual HD session. eKt/V was estimated using Goldstein's logarithmic extrapolation method. Standard Kt/V was calculated using Leypoldt's formula based on eKt/V, duration and dialysis frequency. A spKt/V vs stdKt/V dose/frequency table was then derived from our thrice-weekly data. Using spKt/V of >or=1.2 as the minimal acceptable HD dose, receiver operating characteristic curve analysis was used to determine the corresponding target stdKt/V across a number of potential cutoff values. Single-pool Kt/V >or=1.2 was delivered with near certainty [sensitivity: 93.5%, specificity: 96.7%, area under the curve (AUC): 0.98] when a stdKt/V >or=2.0 was targeted. For a spKt/V >or=1.4, a target of stdKt/V >or=2.2 provided sensitivity and specificity of 73.4 and 96.1%, respectively, with an AUC of 0.94. Our data demonstrate that one should deliver a stdKt/V >or=2.0 for thrice-weekly paediatric HD in order to achieve a spKt/V >or=1.2; and if one wishes to ensure a spKt/V >or=1.4, then the stdKt/V must be >or=2.2. For children receiving a spKt/V >or=1.6 more than thrice weekly, the currently published adult dose/frequency table will overestimate the stdKt/V dose delivered and should be replaced by paediatric derived values.