Objective: Acute kidney injury (AKI) is frequently encountered around 40% in critically ill patients and associate with a high mortality. The objective was to assess the clinical predictors for 28-day mortality in AKI patients requiring renal replacement therapy (RRT).
Materials and Methods: This is a retrospective cohort study from prospectively collected data. AKI patients requiring RRT were included. We collected demographic and laboratory data within 24 hours before the initiation of RRT. We excluded patients with preexisting chronic kidney disease stage 5 and AKI patients requiring peritoneal dialysis. We compared clinical characteristics and analyzed the predictors of mortality of survivors and non-survivors according to 28-day mortality.
Results: We included 122 AKI patients requiring RRT. Mortality rate at day 28 and 90 after AKI diagnosis were 59% (95% confidence interval [CI] 49.7 to 67.8) and 72.1% (95% CI 63.3 to 79.9). On multivariable analysis, clinical predictors for 28-day mortality were serum creatinine before RRT (hazard ratio [HR] 0.84, 95% CI 0.74 to 0.95), SOFA score before initiation of RRT (HR 1.10, 95% CI 1.03 to 1.18), presence of vasopressors before initiation of RRT (HR 2.80, 95% CI 1.03 to 7.64), serum lactate >4 mmol/L before initiation of RRT affected the first 10 days of survival time (HR 2.17, 95% CI 1.03 to 4.57). However, serum lactate >4 mmol/L before initiation of RRT did not affect the after 10 days of survival time (HR 0.99, 95% CI 0.37 to 2.66).
Conclusion: AKI patients with shock and multiorgan failure had a lower chance of survival. In addition, a lower serum creatinine that represents a high fluid overload can predict death as well.

Keywords: Acute kidney injury; Lactate; Mortality; Renal replacement therapy; Vasopressors