Another look at the relationship between protein intake and dialysis dose

It seems reasonable to postulate that an observed relationship between dialysis dose and protein intake reflects improved nutrition with correction of uremic symptoms. This article demonstrates a purely statistical association between the two parameters--protein intake, expressed as normalized protein catabolic rate (NPCR), and dialysis dose quantified as KT/V [the product of urea clearance (K) and treatment time (T) divided by the distribution volume of urea (V)] in peritoneal dialysis. The use of random samples from independent normal distributions of K, V, and urea generation rate (G) for the calculation of KT/V and NPCR reveals that a statistical association is introduced when both protein intake and dialysis dose are normalized proportional to a common distribution V. Not the normalizing parameter V per se, but rather the variability of V accounts for the introduction of this statistical artifact.