FACTORS AFFECTING NPCR IN HEMODIALYZED PATIENTS

The determination of dialysis adequacy is difficult and definitions are in a state of flux (Lindsay). In fact, after fifteen years from the introduction of urea kinetics into clinical practice, nephrologists still do not agree on recognizing the real utility of it. Gotch and Sargent in their mechanistic analysis of the NODS indicated that the dose of small molecules removal could be defined by Kt/V urea. The results of the NODS were depicted in a three-variable plot in which six domains could be seen. Several reports have documented malnutrition as being frequently present in patients on maintenance hemodialysis. It is generally accepted that a suboptimal nutritional status is associated with an increased morbidity and may adversely affect rehabilitation and the quality of life. In 1989 Lindsay et al showed that low levels of Kt/V corresponded with low levels of nPCR and found a direct correlation between the two parameters. On this basis, they suggested the hypothesis of nPCR dependence on Kt/V. The Authors showed a good correlation (r=0.73) between nPCR and Kt/V in 55 patients. This work aims to evaluate the correlation between Kt/V and nPCR, real age and dialytic age in a dialytic population in Southern Italy, during a long period of observation (six years, follow up 2,692 months). One hundred and thirty-four patients were studied in six years of observation. Follow up: 2692 months. Twenty-six patients died during the observation period. The simple regression analysis of nPCR vs. Kt/V, real age and dialytic age was performed in 63 anuric patients. nPCR showed a statistical difference (p<0.01) versus reall age, but no difference versus dialytic age and Kt/V. Our research data show that increasing Kt/V administration does not modify the nPCR of patients with initial and steady low protein intake over a medium time of observation. The same happens in patients with initial and steady high protein intake, when decreasing Kt/V administration in a short period of observation. We confirm that nPCR and Kt/V do not show any mathematical correlation in short and medium times of observation. It is also stressed by the simple regression analysis of data for a selected population of anuric uremics on dialysis thrice weekly for long observation times (between three and six years). Variance analysis (in 8 patients who had used all the membranes) showed differences between Kt/V and dialytic age, but not nPCR and real age. Kt/V and biocompatibility do not appear to be correlated directly with nPCR, because other factors are important in determining the general well-being in uremic patients. Such factors have to be considered when prescribing the dialytic ''dose'' and in clinically evaluating a uremic patient.