Mortality risk factors in intensive care unit patients with acute kidney injury requiring renal replacement therapy: a retrospective cohort study

Background: Mortality of critically-ill patients with acute kidney injury (AKI) requiring renal replacement therapy (RRT) in an intensive-care setting continues to remain high. There is still uncertainty as to which factors should guide clinical judgement. Methods: A cohort of 155 patients admitted to an intensive-care unit and necessitating RRT due to AKI were retrospectively analyzed. Demographic and clinical parameters at the time of RRT initiation were retrieved. Multi-and univariate analyses were performed to determine the impact of different risk factors on mortality. Results: The most common causes of AKI were sepsis (39.3%) and cardiac events (32%). The majority of patients were treated by continuous (67.3%), the others by intermittent RRT. After 30 days, 51.0% of patients survived. Nonsurvivors were older (73 vs. 69 years), had a higher APACHEE II score (30.1 +/- 5.6 vs. 26.5 +/- 7.1), and were more likely to be vasopressor dependent, mechanically ventilated, or treated by continuous RRT. Multivariate analysis revealed that higher age, higher APACHEE II score, and lower serum creatinine at baseline were independent predictors for mortality, whereas histories of diabetes mellitus, arterial hypertension, coronary heart disease, or stroke were not. Conclusion: Critically-ill patients with AKI requiring RRT continue to have a high mortality. Age and APACHE II score showed an impact on mortality whereas traditional cardiovascular risk factors did not. Higher BUN and creatinine levels do not have a negative impact on mortality. Our findings support the current practice that RRT initiation should primarily be guided by clinical decision.