Higher rate and earlier peritonitis in Aboriginal patients compared to non-Aboriginal patients with end-stage renal failure maintained on peritoneal dialysis in Australia: Analysis of ANZDATA

Background: Aboriginal patients maintained on peritoneal dialysis (PD) have a higher rate of technique failure than any other racial group in Australia. Peritonitis accounts for the bulk of these technique failures, but it is uncertain whether the increased risk of peritonitis in Aboriginal patients was independent of associated comorbid conditions, such as diabetes mellitus. Methods: Using data collected by the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA), peritonitis rates and time to first peritonitis were compared between Aboriginal (n = 238) and non-Aboriginal patients (n = 2924) commencing PD in Australia between 1 April 1999 and 31 March 2003. Results: Aboriginal PD patients were younger, and had a higher incidence of diabetes than their non-Aboriginal counterparts. Mean peritonitis rates were significantly higher among Aboriginal (1.15 episodes/year; 95% confidence interval (CI): 1.03-1.28) than non-Aboriginal patients (0.60 episodes/year; 95% CI: 0.57-0.62, P < 0.05). Using multivariate negative binomial regression, independent predictors of higher peritonitis rates include Aboriginal racial origin (adjusted odds ratio 1.78; 95% CI: 1.45-2.19), obesity, age and absence of a recorded dialysate: plasma creatinine ratio (D/P creatinine) measurement. Aboriginal racial origin was also associated with a shorter median time to first peritonitis (9.9 vs 19.3 months, P < 0.05), which remained statistically significant in a multivariate Cox proportional hazards model (adjusted hazard ratio 1.76; 95% CI: 1.47-2.11, P < 0.05). Conclusion: Aboriginal and obese PD patients have a higher rate of peritonitis and a shorter time to first peritonitis, independent of demographic and comorbid factors. Further investigation of the causes of increased peritonitis risk in Aboriginal patients is needed.