Explaining counter-intuitive clinical outcomes predicted by Kt/V

Population-based studies of maintenance hemodialysis patients have demonstr ated a reproducible relationship between the dose of hemodialysis and morta lity and morbidity outcomes. In these analyses, which have aggregated hemod ialysis patient subgroups, improved outcomes are associated with greater do ses of hemodialysis. However, remarkable counterintuitive findings are obse rved if patients are analyzed by subgroups based on their race, gender, and anthropometric and blood-based biomarkers of nutritional state. For exampl e, blacks generally receive lower doses of hemodialysis than whites, but en joy relatively improved survival; patients who receive the highest doses of hemodialysis have an increased death risk; and the dose response curve bet ween hemodialysis and survival is altered based on the patients' body mass index. These seemingly paradoxical relationships between hemodialysis dose and patient survival can be explained because of the use of mathematical ur ea kinetic constructs as clinical outcome predictors; they integrate a meas ure of solute removal (K x t) with an anthropometric surrogate of nutrition , the urea distribution volume (V). Both these measures have an independent influence on patient survival and in some clinical circumstances are of un equal power as clinical outcome predictors. These complex interactions must be kept in perspective as clinical care is delivered in the context of hem odialysis dose.