Adequacy Measurement for the 21st Century: Revisiting Kt/Vurea.

Congressional legislation extending Medicare to cover end-stage kidney disease mandated quality assurance in dialysis care. The Centers for Medicare & Medicaid Services enforces this mandate by establishing quality standards for dialysis facilities, relying on clinical practice guidelines in selecting specific metrics. For evaluating the adequacy of the delivered dialysis dose, Centers for Medicare & Medicaid Services selected the guideline-recommended minimal single pool Kt/V of urea (Kt/V). In this narrative review, we outline the evolution of Kt/V as an adequacy metric, noting that Kt/V alone is insufficient to ensure the clearance of all uremic solutes in patients receiving dialysis. We highlight that the guideline-recommended Kt/V metrics are based on post hoc observational interpretation of randomized controlled trials and are not generalizable to all patients treated with dialysis, particularly patients with substantial residual kidney function. We emphasize that the results of the recent hemodiafiltration trials suggest that dialysis treatment-related factors beyond Kt/V can change patient outcomes. We recommend discontinuing "dialysis adequacy" synonymously with Kt/V and suggest reducing the emphasis on Kt/V from a single dialysis treatment as a key quality metric.