Aims — 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 age ≥65 years as a surrogate for universal drug coverage. Adults with diabetes were followed from 31 March 1997 to 31 March 2011 for occurrence of the composite primary outcome (acute kidney injury, ESRD requiring dialysis, kidney transplantation). Dialysis patients with diabetes were followed from 1 April 1994 to 31 March 2011 for occurrence of death or transplantation.
Results — SES quintile (Q) was inversely associated with the primary outcome in both age groups, although the gradient was higher in those aged <65 years (Q1:Q5 hazard ratio (HR): 1.43; 95% confidence interval (CI): 1.37–1.49) compared to ≥65 years (HR 1.19, CI 1.15–1.24). Low SES was associated with a lower likelihood of kidney transplantation among those aged <65 years (HR 0.77, CI 0.65–0.92). In dialysis patients, low SES was associated with higher mortality (HR 1.09, 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.
Discussion — SES is inversely associated with ESRD outcomes in individuals with diabetes, and this disparity is reduced in those aged ≥65 years, who universally receive prescription drug coverage. Low SES is associated with a higher mortality following dialysis largely explained by lower kidney transplantation rates in poorer populations.