title: Acute kidney injury, long-term renal function and mortality in patients undergoing major abdominal surgery: a cohort analysis.
abstract: BACKGROUND
  Acute kidney injury (AKI) is frequent during hospitalization and may contribute to adverse consequences. We aimed to evaluate long-term adverse renal function and mortality after postoperative AKI in a cohort of patients undergoing major abdominal surgery.
  
  
  METHODS
  We performed a retrospective analysis of adult patients who underwent major non-vascular abdominal surgery between January 2010 and February 2011 at the Department of Surgery II of Hospital de Santa Maria-Centro Hospitalar Lisboa Norte, Portugal. Exclusion criteria were as follows: chronic kidney disease on renal replacement therapy, undergoing renal replacement therapy the week before surgery, death before discharge and loss to follow-up through January 2014. Patients were categorized according to the development of postoperative AKI in the first 48 h after surgery using the Kidney Disease: Improving Global Outcomes classification. AKI was defined by an increase in absolute serum creatinine (SCr) ≥0.3 mg/dL or by a percentage increase in SCr ≥50% and/or by a decrease in urine output to <0.5 mL/kg/h for >6 h. Adverse renal outcomes (need for long-term dialysis and/or a 25% decrease in estimated glomerular filtration rate after hospital discharge) and mortality after discharge were evaluated. Cumulative mortality was analysed with the Kaplan-Meier method and log-rank test and outcome predictive factors with the Cox regression. Significance was set at P < 0.05.
  
  
  RESULTS
  Of 390 selected patients, 72 (18.5%) developed postoperative AKI. The median follow-up was 38 months. Adverse renal outcomes and death after hospital discharge were more frequent among AKI patients (47.2 versus 22.0%, P < 0.0001; and 47.2 versus 20.5%, P < 0.0001, respectively). The 4 year cumulative probability of death was 44.4% for AKI patients, while it was 19.8% for patients with no AKI (log-rank test, P < 0.0001). In multivariate analysis, AKI was a risk factor for adverse renal outcomes (adjusted hazard ratio 1.6, P = 0.046) and mortality (adjusted hazard ratio 1.4, P = 0.043).
  
  
  CONCLUSIONS
  AKI after major abdominal surgery was independently associated with the risk of long-term need for dialysis and/or renal function decline and with the risk of death after hospital discharge.
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Gameiro
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Joana Briosa
authors.initials: JB
authors.lastname: Neves
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Natacha
authors.initials: N
authors.lastname: Rodrigues
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Bekerman
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Melo
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Marta
authors.initials: M
authors.lastname: Pereira
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Teixeira
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Mendes
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: Sofia
authors.initials: S
authors.lastname: Jorge
authors.affiliation: Department of Surgery II , Centro Hospitalar Lisboa Norte, EPE , Lisboa , Portugal.
authors.forename: Rosário
authors.initials: R
authors.lastname: Rosa
authors.affiliation: Department of Medicine , Service of Nephrology and Renal Transplantation , Lisboa , Portugal.
authors.forename: José António
authors.initials: JA
authors.lastname: Lopes
keywords: acute kidney injury; chronic kidney insufficiency; general surgery; mortality