TRENDS OF BASELINE-RISK OF MORTALITY AND OBSERVED 3-YEAR MORTALITY IN INCIDENT DIALYSIS PATIENTS IN GERMANY

Abstract Background and Aims The risk of mortality varies considerably among end stage kidney disease patients. As the population ages, patients on renal replacement therapy are presenting with an increasing number of non-renal complications such as heart failure and, subsequently, an increased mortality risk. Thus, in recent years, patient care in dialysis units has become more complex. In this study we describe trends in baseline risk of mortality and 3-year mortality risk in a sample of incident dialysis patients in Germany. Method The QiN (Quality in Nephrology) dataset is a registry-based observational study in which >90% of all patients treated in dialysis centers of the non-profit kidney care provider KfH are enrolled. In our analyses we included all adult patients beginning hemodialysis (HD) or peritoneal dialysis (PD) treatment between 2008 and 2014 who were enrolled in QiN within 6 months after inception of dialysis. Primary outcome was all-cause death within 3 years. Cox models were censored for transplantation and loss to follow-up. Baseline risk of mortality was assessed by the AROii score (Floege et al. 2015), a predictive model including patient characteristics, laboratory variables and dialysis parameters. In this score higher values indicate greater mortality risk. Results A total of n=20369 patients were analyzed, HD n=18255 (89.6%), PD n=2114 (10.4%). Baseline mortality risk increased over time: AROii score for the 2008/09 incidence cohort was median 8.1 (interquartile range 4.4; 11.9), for the 2010/11 cohort 8.8 (5.0; 12.0) and for the 2012-14 cohort 9.0 (5.0; 12.0), p<0.001. The AROii score was highly predictive for observed 3-year mortality (Hazard Ratio [HR] 1.196 [1.190; 1.203], p<0.001; C-statistic 0.736). In spite of higher baseline mortality risk in patients starting dialysis in more recent years, mortality was lower as compared to the earlier cohorts (HR 0.976 [0.964; 0.988), p<0.001). The results were mainly driven by HD patients. In PD patients baseline mortality risk increased, but no trend on mortality was observed. Conclusion Our results show that patients starting dialysis in Germany have become sicker over the last decade, as indicated by the AROii risk score. Simultaneously the observed risk of mortality decreased in recent years, indicating success of optimized medical treatment including dialysis therapy as well as non-nephrology medical care.