Progression to Stage 4 chronic kidney disease and death, acute kidney injury and hospitalization risk: a retrospective cohort study.

ABSTRACT

BACKGROUND: Chronic kidney disease (CKD) Stage 4 is on the path to kidney failure, but there is little information on the risks associated with progression to Stage 4 per se. The objective of this study is to determine how progression from Stage 3 to Stage 4 CKD alters morbidity and mortality in a referred cohort of patients. METHODS: We conducted a retrospective cohort study consisting of 1607 patients with estimated glomerular filtration rate (eGFR) of 30-59 mL/min/1.73 m(2) referred to a nephrologist at a tertiary care center in Ontario, Canada, between January 2001 and December 2008. Interim progression from Stage 3 to Stage 4 chronic kidney disease was defined by two independent outpatient eGFR values <30 mL/min/1.73 m(2). Death, acute kidney injury (AKI) and all-cause hospitalizations subsequent to Stage 4 progression, but prior to the development of end-stage renal disease (ESRD), ascertained from administrative databases. RESULTS: The mean (standard deviation) baseline eGFR was 43 (8) mL/min/1.73 m(2). Over 2.66 years (interquartile range 1.42-4.45), 344 (21%) patients progressed to Stage 4, 47 (3%) developed ESRD, 188 (12%) patients died, 143 (9%) were hospitalized with AKI and 688 (43%) were hospitalized for any reason. Compared with patients who did not progress to Stage 4, those who did progress had significantly higher adjusted risks of death [hazard ratio (HR) = 2.56, 95% confidence interval (95% CI) 1.75-3.75], AKI (HR = 2.32, 95% CI 1.44-3.74) and all-cause hospitalization (HR = 1.87, 95% CI 1.45-2.42). CONCLUSIONS: Progression from Stage 3 to Stage 4 CKD is associated with increased risks of death, AKI and hospitalization prior to ESRD.