Decline in glomerular filtration rate during pre-dialysis phase and survival on chronic renal replacement therapy

Background. Estimated glomerular filtration rate (eGFR) is widely used in follow-up and assessment of patients before start of chronic renal replacement therapy (RRT). Reported data on impact of eGFR decline pattern during pre-dialysis phase on consequent survival on RRT are, however, non-existent. Methods. Using the database of the Finnish Registry for Kidney Diseases, we conducted a cohort study of all incident adult patients (n ¼ 457) entering chronic RRT in Finland in 1998, with follow-up until 31 December 2008. We included those (n ¼ 319) with three serum creatinine measurements (at ~12 and 3 months and 1 to 2 weeks prior to RRT start) and calculated their slopes of eGFR using the modification of diet in renal disease formula. According to eGFR slopes (in mL/min/1.73m 2 /year), patients were divided into tertiles: most rapid (>8.5, n ¼ 107), intermediate (3.4–8.5, n ¼ 107) and slowest decline (<3.4, n ¼ 105). Results. Median survival time was 5.6 (95% confidence interval 4.2–7.0) years. Compared to the patient group with the slowest eGFR decline, age- and gender-adjusted relative risk of death was 1.1 (0.8–1.5) in the intermediate group and 1.7 (1.2–2.4, P ¼ 0.002) in the most rapid decline group. When further adjusting for kidney disease diagnosis, comorbidities, use of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, body mass index, blood haemoglobin and serum albumin, the association was no longer significant. Conclusions. Rapid decline in eGFR before entering chronic RRT associates with increased mortality on RRT. The elevated mortality appears to be caused by known risk factors for death on RRT.