Delivered dose of renal replacement therapy and mortality in critically ill patients with acute kidney injury.
BACKGROUND
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 >or= 35 ml/kg/hour, IRRT >or= 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.


BACKGROUND
Cochrane Renal Group (CRG110600093).
Department of Anesthesiology and Intensive Care, Hospital Niguarda, Piazza dell'Ospedale Maggiore 3, 20162, Milan, Italy.
Sergio
S
Vesconi
Dinna N
DN
Cruz
Roberto
R
Fumagalli
Detlef
D
Kindgen-Milles
Gianpaola
G
Monti
Anibal
A
Marinho
Filippo
F
Mariano
Marco
M
Formica
Mariano
M
Marchesi
Robert
R
René
Sergio
S
Livigni
Claudio
C
Ronco
D058186:Acute Kidney Injury / Q000401:mortality / Q000628:therapy*; D000328:Adult; D000368:Aged; D016638:Critical Illness; D015314:Dialysis Solutions / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies; D017582:Renal Replacement Therapy / Q000379:methods*
D015314:Dialysis Solutions