Background: The incidence of chronic renal replacement therapy (RRT) varies markedly between Danish nephrology centres. The aim of the present study was to establish if there is regional and social variation in the incidence of chronic RRT in Denmark when analysed according to patient residence. The importance of diabetic nephropathy and patients aged 70 years or older was also studied.
Methods: Incident patients on chronic RRT in the period 1995-2006 were identified in the Danish National Registry on Regular Dialysis and Transplantation. Information on residence, income, educational status and ethnic origin was obtained from Statistics Denmark. Rates of incident RRT patients were standardized for regional differences of sex and age as well as income, educational status and ethnic origin. Poisson regression was used when comparing rates.
Results: Age- and sex-standardized incident chronic RRT rates among individuals with low income or short educational level were higher (P < 0.0001) compared to other groups. Also, standardized rates of patients in total and patients aged 70 years or older were higher in the catchment areas of the nephrology centres located in the two largest cities than for patients with residence in other areas of the country (P < 0.0001). Standardizing for regional differences of ethnic origin did not change the rates. The incident chronic RRT rate caused by diabetic nephropathy was higher for patients with residence in the catchment area of the nephrology centre in the largest city [49 per million people (p.m.p.) (95% CI = 40-57 p.m.p.)] compared to the catchment area of the nephrology centre located in the second largest city [31 (95% CI = 26-37 p.m.p.)] and other areas [29 p.m.p. (95% CI = 26-31 p.m.p.)] in 2001-06. When standardizing for differences in income among the 30-69-year-old persons, the rate of patients with residence in the catchment area of the nephrology centre located in the largest city decreased but was still higher than in other regions (P = 0.0003).
Conclusions: There are marked socio-economic and regional differences in rates of incident RRT patients. The rates of incident RRT patients are highest in the catchment areas of the two largest nephrology centres and this may be partly explained by a higher frequency of end-stage diabetic nephropathy and a new treatment programme targeting frail, mainly elderly, patients.