Comparison of mortality risk for dialysis patients and cadaveric first renal transplant recipients in Ontario, Canada

population-based studies, renal transplantation has been shown to improve s urvival compared to dialysis patients awaiting transplantation in the Unite d States. However, dialysis mortality in the United States is higher than i n Canada. Whether transplantation offers a survival advantage in regions wh ere dialysis survival is superior to that in the United States is uncertain . This study examines a cohort of 1156 patients who started end-stage renal disease (ESRD) therapy and were wait-listed for cadaveric renal transplant ation in the province of Ontario, Canada between January 1, 1990 and Decemb er 31, 1994. Patients were followed from wait-listing for renal transplant (n = 1156), to cadaveric first renal transplant (n = 722), to death, or to study end (December 31, 1995). The annual crude mortality rates for wait-li sted dialysis patients and transplanted patients were 5.0 and 3.4%, respect ively. In Cox proportional hazards models, mortality in wait-listed patient s was associated with increased age and diabetes, but not time from onset o f ESRD to wait-listing. Factors associated with death following transplanta tion include older age, diabetes, and longer time spent on the waiting list before transplantation. In a time-dependent Cox regression model, the rela tive risk of death after transplantation compared to dialysis varied in a t ime-dependent manner. Covariates associated with increased risk included ol der age, diabetes, and time from onset of ESRD to wait-listing. The average relative risk (RR) of dying was 2.91 (95% confidence interval [CI], 1.34 t o 6.32) in the first 30 d after transplantation, but was significantly lowe r 1 yr after transplantation (RR 0.25; 95% CI, 0.14 to 0.42), indicating a beneficial long-term effect when compared to wait-listed dialysis patients. This long-term benefit was most evident in subgroups of patients with diab etes (RR 0.38; 95% CI, 0.17 to 0.87) and glomerulonephritis (RR 0.13; 95% C I, 0.04 to 0.39) as the cause of ESRD. The survival advantage associated wi th renal transplantation is evident in this cohort of patients with a lower wait-listed dialysis mortality than that reported previously in the United States. The magnitude of the treatment effect is consistent across studies .