Mortality risks of peritoneal dialysis and hemodialysis

Studies of outcomes associated with dialysis therapies have yielded conflic ting results. Bloembergen et al showed that prevalent patients on continuou s ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal di alysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, a nd Fenton et al, analyzing Canadian incident patients, found a 27% lower ri sk. Attempting to reconcile these differences, we evaluated incident Medica re patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplanta tion, death, loss to follow-up, 60 days after modality change, or end of th e study period. For each 3-month survival period, we used an interval Poiss on regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specif ic mortality, and proportionality was addressed in both regressions by sepa rating diabetic and nondiabetic patients. The Poisson regressions showed CA PD/CCPD to have outcomes comparable with or significantly better than hemod ialysis, although results varied over time. The Cox regression found a lowe r mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 y ears: risk ratio [RR] = 0.61; CI, 0.59 to 0.66; women age 55 years or older : RR = 0.87; CI, 0.84 to 0.91; men younger than 55 years: RR = 0.72; CI, 0. 67 to 0.77; men age 55 years or older: RR = 0.87; CI, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; CI, 0.82 to 0.94; men: RR = 0.86; CI, 0.81 to 0.92). The risk of all-cause death for fe male diabetics 55 years of age and older, in contrast, was 1.21 (CI, 1.17 t o 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be ass ociated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over t ime, a nonproportionality that makes survival analyses vulnerable to the le ngth of follow-up. Further investigation is needed to evaluate both the pot ential explanations for these findings and the use of more advanced statist ical methods in the analysis of mortality rates associated with these dialy tic therapies. (C) 1998 by the National Kidney Foundation, Inc.