Impact of Socioeconomic Status on Incidence of End-Stage Renal Disease and Mortality After Dialysis in Adults With Diabetes

Abstract

Objectives: To determine whether low socioeconomic status (SES), with or without universal drug coverage, predicts end-stage renal disease (ESRD) and survival after dialysis in patients with diabetes.

Methods: We conducted a population-based retrospective cohort study in Ontario, Canada. We used ≥65 years of age as a surrogate for universal drug coverage. Adults with diabetes were followed from March 31, 1997 to March 31, 2011 for occurrence of the composite primary outcome (acute kidney injury, ESRD requiring dialysis or kidney transplantation). Patients on dialysis with diabetes were followed from April 1, 1994 to March 31, 2011 for occurrence of death or transplantation.

Results: SES quintile (Q) was inversely associated with the primary outcome in both age groups; however, the gradient was higher in those <65 years of age (Q1:Q5 hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.37-1.49) compared with ≥65 years of age (HR, 1.19; 95% CI, 1.15-1.24). Low SES was associated with a lower likelihood of kidney transplantation among those <65 years of age (HR, 0.77; 95% CI, 0.65-0.92). In patients on dialysis, low SES was associated with higher mortality (HR, 1.09; 95% CI, 1.02-1.16) in both age groups. This association was eliminated after accounting for the decreased rates of kidney transplantation in lower SES groups.

Conclusions: SES is inversely associated with ESRD outcomes in individuals with diabetes, and this disparity is reduced in those ≥65 years of age who universally receive prescription drug coverage. Low SES is associated with a higher mortality after dialysis, largely explained by lower kidney transplantation rates in poorer populations.

Keywords: chronic; chronique; diabetes mellitus; diabète sucré; epidemiology; insuffisance rénale; kidney failure; socioeconomic status; statut socio-économique; épidémiologie.