Declining comorbidity-adjusted mortality rates in English patients receiving maintenance renal replacement therapy

We aimed to compare long-term mortality trends in end-stage renal disease versus general population controls after accounting for differences in age, sex and comorbidity. Cohorts of 45,000 patients starting maintenance renal replacement therapy (RRT) and 5·6 million hospital controls were identified from two large electronic hospital inpatient datasets: the Oxford Record Linkage Study (1965-1999) and all-England Hospital Episode Statistics (2000-2011). All-cause and cause-specific 3-year mortality rates for both populations were calculated using Poisson regression and standardized to the age, sex, comorbidity structure of an ‘average’ 1970-2008 RRT population. The median age at initiation of RRT in 1970-1990 was 49y (interquartile cut-offs 36–60y) and 63y (49–73y) by 2006-2008. Over that period, there were increases in the prevalence of vascular disease (from 10·0 to 28·3%) and diabetes (from 6·7 to 34·3%). After accounting for age, sex and comorbidity differences, standardized 3-year all-cause mortality rates in treated ESRD patients between 1970 and 2011 fell by about one-half (relative decline 51%, 95%CI 41–60%) steeper than the one-third decline (34%, 95%CI 31–36%) observed in the general population. Declines in 3-year mortality rates were evident among those who received a kidney transplant and those who remained on dialysis, and among those with and without diabetes. In conclusion, the full extent of mortality rate declines among RRT patients since 1970 is only apparent when changes in comorbidity over time are taken into account. This approach suggests mortality rates in RRT patients have declined faster than the general population