Free to Be in Peritoneal Dialysis: Without Kt/V?

Since its introduction in 1985, Kt/V urea has played a pivotal role as a marker of "dialysis adequacy." Over the decades, multiple clinical practice guidelines have adopted and subsequently relaxed Kt/V targets, which were then transformed into quality metrics in various health care systems, including the United States. In this perspective, we explore the historical origins of Kt/V, focusing on its adaptation to peritoneal dialysis. We critically examine literature linking Kt/V to patient outcomes and explore the limitations of Kt/V-including reliance on urea removal alone as a surrogate for the clearance of all uremic toxins, the flawed assumption of equivalence between residual kidney and dialytic urea clearances, and the challenges in estimating the volume of distribution of urea. We propose alternative quality metrics that may better reflect meaningful patient outcomes such as preserving residual kidney function, optimizing nutrition and volume status, minimizing dialysis-related infections, and maintaining quality of life. Ultimately, we call for a shift away from Kt/V-centric quality frameworks and the concept of "adequate" dialysis, advocating instead for a more holistic model of high-quality, person-centered dialysis care, a model in which kidney care practitioners are empowered to provide high-quality peritoneal dialysis care without the constraints of Kt/V.