Comparison of single-pool and equilibrated Kt/V values for pediatric hemodialysis prescription management: analysis from the Centers for Medicare & Medicaid Services Clinical Performance Measures Project.

Current formulas that estimate the delivered dose of hemodialysis rely upon pre- and post-treatment blood urea nitrogen (BUN) concentrations for calculation. Single-pool kinetic modeling (spKt/V) uses a convenient 30-s post-dialysis BUN sample but does not take urea rebound into account. Double-pool modeling (eKt/V) uses an equilibrated BUN (eqBUN) and is the best reflection of the true urea mass removed by hemodialysis but is inconvenient for patients and costly to the dialysis unit to wait to obtain an eqBUN sample. We compared simple spKt/V and eKt/V estimation formulas using data obtained from the Centers for Medicare & Medicaid Services (CMS) End Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) Project to determine how frequently these two results would lead to different prescription management. We set an expected difference Kt/V (spKt/V-eKt/V) of 0.20 based on results of the Hemodialysis (HEMO) Study; 1,513 paired spKt/V and estimated eKt/V results were available for comparison. For patients with an arteriovenous fistula (AVF) or arteriovenous graft (AVG) (n=720), mean spKt/V and estimated eKt/V were 1.62+/-0.30 and 1.37+/-0.26, respectively. For patients with a catheter (n=793), mean spKt/V and estimated eKt/V were 1.53+/-0.32 and 1.33+/-0.29, respectively. Examination of the different spKt/V and estimated eKt/V pairings revealed a greater adequacy discordance rate between a 0.20 difference in spKt/V and estimated eKt/V at higher Kt/V values, but Kt/V discordance rates only varied from 0.3 to 5.5% depending on the paired Kt/V values used.