Survival of Indigenous Australians receiving renal replacement therapy: closing the gap?

Abstract

OBJECTIVES: To compare mortality rates for Indigenous and non-Indigenous Australians commencing renal replacement therapy (RRT) over time and by categories of remoteness of place of residence. DESIGN, SETTING AND PARTICIPANTS: An observational cohort study of Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) data on Indigenous and non-Indigenous Australians registered with ANZDATA who commenced RRT from 1 January 1995 to 31 December 2009 and were followed until 31 December 2011. MAIN OUTCOME MEASURES: Five-year all-cause mortality for Indigenous and non-Indigenous patients in three cohorts (1995-1999, 2000-2004 and 2005-2009) and five remoteness (of place of residence) categories. RESULTS: Indigenous patients were younger, more likely to have diabetes, be referred late and be from a more remote area than non-Indigenous patients. Age and comorbid conditions increased with successive cohorts for both groups. Unadjusted analysis (using the log-rank test) showed an increased risk of death for Indigenous patients in the 1995-1999 (P = 0.02) and 2000-2004 (P = 0.03) cohorts, but not for the 2005-2009 cohort (P = 0.7). However, a Cox proportional hazards model adjusted for covariates (age, sex, late referral and comorbid conditions [diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, lung disease], and body mass index < 18.5 kg/m(2) and > 30 kg/m(2)) showed the following Indigenous:non-Indigenous hazard ratios (with 95% CIs) for major capital cities: 1995-1999, 1.47 (1.21-1.79); 2000-2004, 1.35 (1.12-1.63); and 2005-2009, 1.37 (1.14-1.66). CONCLUSIONS: Although unadjusted analysis suggests that the survival gap between Indigenous and non-Indigenous patients receiving RRT has closed, there remains a significant disparity in survival after adjusting for the variables considered in our study.