Mortality and Access to Kidney Transplantation in Patients with Sickle Cell Disease-Associated Kidney Failure

Abstract

Background and objectives: Patients with sickle cell disease-associated kidney failure have high mortality, which might be lowered by kidney transplantation. However, because they show higher post-transplant mortality compared with patients with other kidney failure etiologies, kidney transplantation remains controversial in this population, potentially limiting their chance of receiving transplantation. We aimed to quantify the decrease in mortality associated with transplantation in this population and determine the chance of receiving transplantation with sickle cell disease as the cause of kidney failure as compared with other etiologies of kidney failure.

Design, setting, participants, & measurements: Using a national registry, we studied all adults with kidney failure who began maintenance dialysis or were added to the kidney transplant waiting list in 1998-2017. To quantify the decrease in mortality associated with transplantation, we measured the absolute risk difference and hazard ratio for mortality in matched pairs of transplant recipients versus waitlisted candidates in the sickle cell and control groups. To compare the chance of receiving transplantation, we estimated hazard ratios for receiving transplantation in the sickle cell and control groups, treating death as a competing risk.

Results: Compared with their matched waitlisted candidates, 189 transplant recipients with sickle cell disease and 220,251 control recipients showed significantly lower mortality. The absolute risk difference at 10 years post-transplant was 20.3 (98.75% confidence interval, 0.9 to 39.8) and 19.8 (98.75% confidence interval, 19.2 to 20.4) percentage points in the sickle cell and control groups, respectively. The hazard ratio was also similar in the sickle cell (0.57; 95% confidence interval, 0.36 to 0.91) and control (0.54; 95% confidence interval, 0.53 to 0.55) groups (interaction P=0.8). Nonetheless, the sickle cell group was less likely to receive transplantation than the controls (subdistribution hazard ratio, 0.73; 95% confidence interval, 0.61 to 0.87). Similar disparities were found among waitlisted candidates (subdistribution hazard ratio, 0.62; 95% confidence interval, 0.53 to 0.72).

Conclusions: Patients with sickle cell disease-associated kidney failure exhibited similar decreases in mortality associated with kidney transplantation as compared with those with other kidney failure etiologies. Nonetheless, the sickle cell population was less likely to receive transplantation, even after waitlist registration.

Keywords: access to care; anemia; kidney failure; kidney transplantation; mortality; sickle cell; sickle cell disease; survival benefit.