title: Progression to Stage 4 chronic kidney disease and death, acute kidney injury and hospitalization risk: a retrospective cohort study.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  Progression from Stage 3 to Stage 4 CKD is associated with increased risks of death, AKI and hospitalization prior to ESRD.
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Maneesh
authors.initials: M
authors.lastname: Sud
authors.affiliation: Division of Nephrology, Seven Oaks General Hospital, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Navdeep
authors.initials: N
authors.lastname: Tangri
authors.affiliation: Department of Biostatistics, University Health Network, Toronto, Ontario, Canada Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Melania
authors.initials: M
authors.lastname: Pintilie
authors.affiliation: Division of Nephrology, Tufts Medical Centre, Boston, MA, USA.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levey
authors.affiliation: Division of Nephrology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada Institute of Health Policy Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: David M J
authors.initials: DM
authors.lastname: Naimark
mesh_terms: D058186:Acute Kidney Injury / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006760:Hospitalization; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors
keywords: chronic kidney disease; dialysis; end-stage renal disease; epidemiology; mortality