[Influence of time of initiation of continuous renal replacement therapy on prognosis of critically ill patients with acute kidney injury].

OBJECTIVE: To investigate the influence of the time of initiation of continuous renal replacement therapy (CRRT) on the survival and recovery of renal function in survivors of critically ill patients with acute kidney injury (AKI).

METHODS: A retrospective analysis was performed on the data of critically ill patients with AKI, who were treated with CRRT from January 1, 2009 to June 30, 2011 in the Fourth Hospital of Hebei Medical University. According to Acute Kidney Injury Net (AKIN) classification at the beginning of CRRT, patients were stratified into AKIN 1, 2, 3 stages. The survival rate and kidney outcome in survivors were compared among these three AKIN groups. Additionally, the association among three influencing factors (duration of CRRT, CRRT dose and the filter life) and prognosis was analyzed.

RESULTS: Fifty-two patients were enrolled, among them 15 were in AKIN 1 stage, 23 in AKIN 2 stage, and 14 in AKIN 3 stage (among them the number of female patients was 14, 16, 6, respectively, P=0.014). (1) Survival analysis: the 28-, 90-, and 180-day survival rate of AKIN 1, 2 and 3 stages (28 days: 53.3%, 52.2%, 61.5%; 90 days: 46.7%, 31.8%, 46.2%; 180 days: 35.7%, 22.7%, 46.2%), intensive care unit (ICU) survival rate (60.0%, 65.2%, 71.4%), and hospital survival rate (60.0%, 60.9%, 71.4%) showed no significant difference (all P>0.05). COX proportional hazards model analysis showed that the 28-day survival rate was significantly correlated with the CRRT dose [relative risk (RR)=0.922, 95% confidence interval (95%CI) 0.856-0.994, P<0.05]. (2) Outcome of renal function in survivors: no significant difference in renal function recovery was found 28, 90, 180 days among AKIN 1, 2 and 3 stages after CRRT (28 days: 75.0%, 66.7%, 75.0%; 90 days: 85.7%, 71.4%, 100.0%; 180 days: 80.0%, 60.0%, 100.0%, all P>0.05). Logistic regression analysis showed that it was correlated with none of the four influencing factors (gender, the filter life, duration of CRRT and CRRT dose).

CONCLUSIONS: Our results indicated that the time of initiation of CRRT by AKIN classification has no effect on the 28-, 90-, 180-day survival rate, ICU survival rate and outcome of renal function in survivors of critically ill patients with AKI. Improving CRRT dose may improve 28-day survival rate.