Differences in survival on chronic dialysis treatment between ethnic groups in Denmark: a population-wide, national cohort study.

Background: In Western countries, black and Asian dialysis patients experience better survival compared with white patients. The aim of this study is to compare the survival of native Danish dialysis patients with that of dialysis patients originating from other countries and to explore the association between the duration of residence in Denmark before the start of dialysis and the mortality on dialysis.

Methods: We performed a population-wide national cohort study of incident chronic dialysis patients in Denmark (≥18 years old) who started dialysis between 1995 and 2010.

Results: In total, 8459 patients were native Danes, 344 originated from other Western countries, 79 from North Africa or West Asia, 173 from South or South-East Asia and 54 from sub-Saharan Africa. Native Danes were more likely to die on dialysis compared with the other groups (crude incidence rates for mortality: 234, 166, 96, 110 and 53 per 1000 person-years, respectively). Native Danes had greater hazard ratios (HRs) for mortality compared with the other groups {HRs for mortality adjusted for sociodemographic and clinical characteristics: 1.32 [95% confidence interval (CI) 1.14-1.54]; 2.22 [95% CI 1.51-3.23]; 1.79 [95% CI 1.41-2.27]; 2.00 [95% CI 1.10-3.57], respectively}. Compared with native Danes, adjusted HRs for mortality for Western immigrants living in Denmark for ≤10 years, >10 to ≤20 years and >20 years were 0.44 (95% CI 0.27-0.71), 0.56 (95% CI 0.39-0.82) and 0.86 (95% CI 0.70-1.04), respectively. For non-Western immigrants, these HRs were 0.42 (95% CI 0.27-0.67), 0.52 (95% CI 0.33-0.80) and 0.48 (95% CI 0.35-0.66), respectively.

Conclusions: Incident chronic dialysis patients in Denmark originating from countries other than Denmark have a better survival compared with native Danes. For Western immigrants, this survival benefit declines among those who have lived in Denmark longer. For non-Western immigrants, the survival benefit largely remains over time.