Association of Kt/V and Creatinine Clearance With Outcomes in Anuric Peritoneal Dialysis Patients

Background

The 2006 Kidney Disease Outcomes Quality Initiative recommended a minimum total Kt/V of 1.7, eliminated creatinine clearance (Ccr) as a target, and recommended the use of ideal body weight to calculate Kt/V. We assessed these recommendations as predictors of outcomes in anuric peritoneal dialysis patients.

Study Design

Retrospective observational study using administrative data.

Setting & Participants

1,432 peritoneal dialysis patients with anuria from January 1, 1994, to January 31, 2005, in a national sample (1,428 with Kt/V, 1,416 with Ccr).

Predictors

Kt/V and Ccr at anuria; Kt/V based on actual body weight and ideal body weight.

Outcomes & Measurements

Association of dialysis adequacy with mortality and time to first hospitalization after anuria assessed by using accelerated failure time models.

Results

293 anuric patients had Kt/V less than 1.7, 366 had Kt/V of 1.7 to 2.0, and 769 had Kt/V greater than 2.0, using actual body weight for calculation. In unadjusted analyses, Kt/V calculated using actual body weight both less than 1.7 (−41.3%; 95% confidence interval [CI], −55.5 to −22.6) and 1.7 to 2.0 (−26.1%; 95% CI, −42.6 to −4.6) were associated with shorter time to mortality. Kt/V calculated using actual body weight less than 1.7 was associated with shorter time to hospitalization (−38.1%; 95% CI, −50.0 to −23.4), but Kt/V calculated using actual body weight of 1.7 to 2.0 was not a significant predictor (−3.3%; 95% CI, −21.1 to 18.6). After adjustment, Kt/V calculated using actual body weight less than 1.7 remained associated with mortality (−25.3%; 95% CI, −41.1 to −4.8) and hospitalization (−33.4%; 95% CI, −47.1 to −16.0). Ccr did not predict mortality. In unadjusted analysis, Ccr was not associated with hospitalization, but after adjustment, Ccr less than 50 L/wk/1.73 m² was significantly associated with shorter time to hospitalization (−19.9%; 95% CI, −35.0 to −1.3). Kt/V using ideal body weight was not a significant predictor in adjusted models.

Limitations

This study was nonrandomized, with few malnourished patients. In addition, there is a potential for informative censoring for transfer to hemodialysis therapy before anuria.

Conclusions

Kt/V calculated using actual body weight less than 1.7 in anuric peritoneal dialysis patients is associated with increased mortality and hospitalization. Use of ideal body weight to calculate Kt/V weakened the associations with outcomes and therefore cannot be recommended.

Index Words: Peritoneal dialysis, adequacy, mortality, hospitalization