Low renal replacement therapy incidence among slowly progressing elderly chronic kidney disease patients referred to nephrology care: an observational study

BACKGROUND Elderly patients with advanced chronic kidney disease (CKD) have a high risk of death before reaching end-stage kidney disease. In order to allocate resources, such as advanced care nephrology where it is most needed, it is essential to know which patients have the highest absolute risk of advancing to renal replacement therapy (RRT). METHODS We included all nephrology-referred CKD stage 3b-5 patients in Sweden 2005-2011 included in the Swedish renal registry (SRR-CKD) who had at least two serum creatinine measurements one year apart (+/- 6 months). We followed these patients to either initiation of RRT, death, or September 30, 2013. Decline in estimated glomerular filtration rate (eGFR) (%) was estimated during the one-year baseline period. The patients in the highest tertile of progression (>18.7% decline in eGFR) during the initial year of follow-up were classified as "fast progressors". We estimated the cumulative incidence of RRT and death before RRT by age, eGFR and progression status using competing risk models. RESULTS There were 2119 RRT initiations (24.2%) and 2060 deaths (23.5%) before RRT started. The median progression rate estimated during the initial year was -8.8% (Interquartile range [IQR] - 24.5-6.5%). A fast initial progression rate was associated with a higher risk of RRT initiation (Sub Hazard Ratio [SHR] 2.24 (95% confidence interval [CI] 2.00-2.51) and also a higher risk of death before RRT initiation (SHR 1.27 (95% CI 1.13-1.43). The five year probability of RRT was highest in younger patients (<65 years) with fast initial progression rate (51% in CKD stage 4 and 76% in stage 5), low overall in patients >75 years with a slow progression rate (7, 13, and 25% for CKD stages 3b, 4 and 5 respectively), and slightly higher in elderly patients with a fast initial progression rate (28% in CKD stage 4 and 47% in CKD stage 5) or with diabetic kidney disease. CONCLUSIONS The 5-year probability of RRT was low among referred slowly progressing CKD patients >75 years of age because of the competing risk of death.