Trends in mortality on peritoneal dialysis: Canada, 1981-1997

Several technical and nontechnical improvements in peritoneal dialysis (PD) have occurred during recent years. Since few previous studies have examine d trends in PD mortality over time, and to determine whether enhancements i n PD have translated into improved patient outcomes, mortality rates among the 17,900 patients receiving PD in Canada during the period 1981-1997 were analyzed. Mortality rate ratios (RR) were estimated using Poisson regressi on, adjusting for age, race, gender, primary renal diagnosis, follow-up tim e, and type of PD (continuous ambulatory/cyclic versus intermittent). Adjus ted mortality rates decreased significantly by calendar period, the reducti on being monotonic: RR = 0.81, 95% confidence interval [CI], 0.75 to 0.87 f or 1986-1989; RR = 0.73, 95% CI, 0.67 to 0.78 for 1990-1993; RR = 0.63, 95% CI, 0.58 to 0.67 for 1994-1997, with 1981-1985 serving as the reference pe riod (RR = 1, fixed). The improvement in mortality was fairly consistent ac ross patient subpopulations. When analyzed separately by follow-up time win dow, the mortality decrease was strongest in the first 12 mo after renal re placement therapy initiation. Supplementary analysis revealed that the tren d in mortality rates was not attributable to corresponding trends in transp lantation or technique failure rates, or modality switching patterns. Resul ts were quite similar whether based on an "as-treated" or "intent-to-treat" analysis. More extensive data on practice patterns would empower future st udies to elucidate the cause/effect relationship between PD practice patter ns and patient survival.