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 m(2) 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.