Research

Delivered dose of renal replacement therapy and mortality in critically ill patients with acute kidney injury

Sergio Vesconi^{* 1} , Dinna N Cruz^{* 2} , Roberto Fumagalli³ , Detlef Kindgen-Milles⁴ , Gianpaola Monti¹ , Anibal Marinho⁵ , Filippo Mariano⁶ , Marco Formica⁷ , Mariano Marchesi⁸ , René Robert⁹ , Sergio Livigni¹⁰ and Claudio Ronco² for the DOse REsponse Multicentre International collaborative Initiative (DO-RE-MI Study Group)

¹Department of Anesthesiology and Intensive Care, Hospital Niguarda, Piazza dell'Ospedale Maggiore 3, 20162, Milan, Italy

²Department of Nephrology, Dialysis and Transplantation, St Bortolo Hospital, Viale Rodolfi 37, 36100 Vicenza, Italy

³Department of Anaesthesiology and Intensive Care I, St Gerardo dei Tintori Hospital, Via giovanni Pergolesi 33, 20100 Monza, Italy

⁴Anesthesiology Clinic, University of Düsseldorf, Moorenstrasse 5, 40225 Germany

⁵Hospital Center of Porto, Alameda do Prof. Hernâni Monteiro, 4200 Paranhos, Porto, Portugal

⁶Nephrology and Dialysis Unit, CTO Hospital, Via Gianfranco Zuretti 29, 10126 Turin, Italy

⁷Department of Nephrology, Hospital Santa Croce e Carle, Via Michele Coppino 26, 12100 Cuneo, Italy

⁸Department of Anaesthesiology and Intensive Care, Riuniti di Bergamo Hospital, Via Tito Livio 2, 24123 Bergamo, Italy

⁹Intensive Care Unit, University of Poitiers, 2, rue de la Miletrie, 86021, Poitiers, France

¹⁰Department of Intensive Care, Giovanni Bosco Hospital, Piazza Del Donatore di Sangue 3, 10154 Torino, Italy

author email corresponding author email* Contributed equally

Critical Care 2009, 13:R57doi:10.1186/cc7784

Published:	15 April 2009

See related commentary by Lameire et al., http://ccforum.com/content/13/3/155

Abstract

Introduction

The optimal dialysis dose for the treatment of acute kidney injury (AKI) is controversial. We sought to evaluate the relationship between renal replacement therapy (RRT) dose and outcome.

Methods

We performed a prospective multicentre observational study in 30 intensive care units (ICUs) in eight countries from June 2005 to December 2007. Delivered RRT dose was calculated in patients treated exclusively with either continuous RRT (CRRT) or intermittent RRT (IRRT) during their ICU stay. Dose was categorised into more-intensive (CRRT ≥ 35 ml/kg/hour, IRRT ≥ 6 sessions/week) or less-intensive (CRRT < 35 ml/kg/hour, IRRT < 6 sessions/week). The main outcome measures were ICU mortality, ICU length of stay and duration of mechanical ventilation.

Results

Of 15,200 critically ill patients admitted during the study period, 553 AKI patients were treated with RRT, including 338 who received CRRT only and 87 who received IRRT only. For CRRT, the median delivered dose was 27.1 ml/kg/hour (interquartile range (IQR) = 22.1 to 33.9). For IRRT, the median dose was 7 sessions/week (IQR = 5 to 7). Only 22% of CRRT patients and 64% of IRRT patients received a more-intensive dose. Crude ICU mortality among CRRT patients were 60.8% vs. 52.5% (more-intensive vs. less-intensive groups, respectively). In IRRT, this was 23.6 vs. 19.4%, respectively. On multivariable analysis, there was no significant association between RRT dose and ICU mortality (Odds ratio (OR) more-intensive vs. less-intensive: CRRT OR = 1.21, 95% confidence interval (CI) = 0.66 to 2.21; IRRT OR = 1.50, 95% CI = 0.48 to 4.67). Among survivors, shorter ICU stay and duration of mechanical ventilation were observed in the more-intensive RRT groups (more-intensive vs. less-intensive for all: CRRT (median): 15 (IQR = 8 to 26) vs. 19.5 (IQR = 12 to 33.5) ICU days, P = 0.063; 7 (IQR = 4 to 17) vs. 14 (IQR = 5 to 24) ventilation days, P = 0.031; IRRT: 8 (IQR = 5.5 to 14) vs. 18 (IQR = 13 to 35) ICU days, P = 0.008; 2.5 (IQR = 0 to 10) vs. 12 (IQR = 3 to 24) ventilation days, P = 0.026).

Conclusions

After adjustment for multiple variables, these data provide no evidence for a survival benefit afforded by higher dose RRT. However, more-intensive RRT was associated with a favourable effect on ICU stay and duration of mechanical ventilation among survivors. This result warrants further exploration.

Trial Registration

Cochrane Renal Group (CRG110600093).