High creatinine excretion ratio predicts a good outcome in peritoneal dialysis patients

The creatinine excretion (CrEx) ratio was first described as a method for detecting noncompliance in peritoneal dialysis (PD) patients. However, a high CrEx ratio is not specific for noncompliance and may also be found in compliant patients with a relatively greater lean body mass (LBM). A cohort of 44 PD patients was followed up for a mean of 13 +/- 8 months after measurement of baseline CrEx ratio to investigate whether greater values were predictive of good or poor clinical outcomes. During this follow-up, 11 patients died, 12 patients transferred to hemodialysis, 4 patients underwent transplantation, 1 patient recovered renal function, and 16 patients continued on PD. The mean CrEx ratio in all patients was 1.14 +/- 0.32. It did not differ between men and women (1.15 versus 1.13, respectively; P = 0.76) but showed a trend toward being less in patients with diabetes (1.03 versus 1.19; P = 0. 19). The mean weekly Kt/V, weekly creatinine clearance, normalized protein equivalent of nitrogen appearance, and serum albumin values were 2.18 +/- 0.57, 73.57 +/- 33.75 L/1.73 m(2), 0.80 +/- 0.22 g/kg/d, and 3.22 +/- 0.59 g/dL, respectively. Technique failure (P < 0.001) and death (P < 0.05) were significantly more common in patients with a CrEx ratio less than 1 compared with those with a CrEx ratio greater than 1. On Cox regression analysis, the CrEx ratio was the only significant predictor of technique failure and was also an independent predictor of death. High CrEx ratio is a predictor of good, rather than poor, outcome in PD patients, perhaps because it is primarily an index of nutrition. This further weakens the argument that it is a reliable or useful marker of noncompliance.