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Open Access Highly Accessed Research

Timing of renal replacement therapy initiation by AKIN classification system

Tacyano T Leite1, Etienne Macedo2, Samuel M Pereira3, Sandro RC Bandeira3, Pedro HS Pontes3, André S Garcia3, Fernanda R Militão3, Irineu MM Sobrinho3, Livia M Assunção3 and Alexandre B Libório145*

Author Affiliations

1 Division of Nephrology, General Hospital of Fortaleza, Rua Ávila Goulart no. 900, 60175-295, Fortaleza, Brazil

2 Nephrology Department, University of São Paulo, Av. Dr. Eneas Carvalho de Aguiar no. 255, 05403-000, São Paulo, Brazil

3 Medical Course, UNIFOR, Av. Washington Soares no. 1321, 60811-905, Fortaleza, Brazil

4 Internal Medicine, Faculdade de Medicina, Universidade Federal do Ceará, Rua Alexandre Baraúna no. 900, 60430-160, Fortaleza, Brazil

5 Nephrology, Cancer Institute of Ceará, R. Papi Júnior no.1222, 60430-230, Fortaleza, Brazil

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Critical Care 2013, 17:R62  doi:10.1186/cc12593

Published: 2 April 2013



Previous studies using Acute Kidney Injury Network (AKIN)/RIFLE criteria to classify early initiation of renal replacement therapy (RRT) have defined it as the therapy started in less severe AKIN/RIFLE stages. Generally, these studies failed in demonstrating measurable benefits.


We compared RRT initiation in critically ill patients and defined early or late RRT in reference to timing after stage 3 AKIN was met: patients beginning RRT within 24 hours after acute kidney injury (AKI) stage 3 were considered early starters. AKIN criteria were evaluated by both urine output (UO) and serum creatinine (sCr) and patients with acute-on-chronic kidney disease were excluded. A propensity score methodology was used to control variables.


A total of 358 critically ill patients were submitted to RRT. Only 150 patients with pure AKI at stage 3 were analyzed. Mortality was lower in the early RRT group (51.5 vs. 77.9%, P = 0.001). After achieving balance between the groups using a propensity score, there was a significant 30.5 (95% confidence interval [CI] 14.4 to 45.2%, P = 0.002) relative decrease of mortality in the early RRT group. Moreover, patients on the early RRT group had lower duration of mechanical ventilation, time on RRT and a trend to lower intensive care unit (ICU) length of stay.


For the first time, AKIN was used with UO criterion to evaluate early and late RRT. Using a time-based approach could be a better parameter to access the association between RRT initiation and outcomes in patients with AKI.