AKI complications in critically ill patients: association with mortality rates and RRT

• Published in: Clinical journal of the American Society of Nephrology 2015-01, Vol.10 (1), p.21-28
• Main Authors: Libório, Alexandre Braga, Leite, Tacyano Tavares, Neves, Fernanda Macedo de Oliveira, Teles, Flávio, Bezerra, Candice Torres de Melo
• Format: Article
• Language: English
• Subjects: Acidosis - mortality; Acidosis - therapy; Acute Kidney Injury - complications; Acute Kidney Injury - diagnosis; Acute Kidney Injury - mortality; Acute Kidney Injury - therapy; Adolescent; Adult; Aged; Aged, 80 and over; Azotemia - mortality; Azotemia - therapy; Boston; Chi-Square Distribution; Critical Illness; Databases, Factual; Female; Hospital Mortality - trends; Hospitals, University; Humans; Hyperkalemia - mortality; Hyperkalemia - therapy; Intensive Care Units; Logistic Models; Male; Middle Aged; Multivariate Analysis; Odds Ratio; Original; Propensity Score; Proportional Hazards Models; Renal Replacement Therapy - adverse effects; Renal Replacement Therapy - mortality; Retrospective Studies; Risk Assessment; Risk Factors; Severity of Illness Index; Time Factors; Treatment Outcome; Water-Electrolyte Imbalance - mortality; Water-Electrolyte Imbalance - therapy; Young Adult
• ISSN: 1555-9041; 1555-905X
• DOI: 10.2215/CJN.04750514

AKI is associated with short- and long-term mortality. However, the exact contribution of AKI complications to the burden of mortality and whether RRT has any beneficial effect on reducing mortality rates in critically ill AKI patients are unknown. This was a retrospective analysis using data from the Multiparameter Intelligent Monitoring in Intensive Care II project. A total of 18,410 adult patients were enrolled from four intensive care units from a university hospital from 2001 to 2008. Overall, 10,245 patients developed AKI. After adjustments, the odds ratios (ORs) for hospital mortality were 1.73 (95% confidence interval [95% CI], 1.52 to 1.98) for AKI stage 1, 1.88 (95% CI, 1.57 to 2.25) for stage 2, and 2.89 (95% CI, 2.41 to 3.46) for stage 3. Totals of 33%, 59%, and 70% of the excess mortality rates associated with AKI stages 1, 2, and 3, respectively, were attenuated by the inclusion of each AKI-related complication in the model. The main burden of excess hospital mortality associated with AKI was attenuated by metabolic acidosis and cumulative fluid balance. Long-term mortality was not attenuated by any of the associated complications. Next, we used two different approaches to explore the associations between RRT, AKI complications, and hospital mortality: multivariate analysis and propensity score matching. In both approaches, the sensitivity analysis for RRT was associated with a better hospital survival in only the following AKI-related subgroups: hyperkalemia (OR, 0.55; 95% CI, 0.35 to 0.85), metabolic acidosis (OR, 0.70; 95% CI, 0.53 to 0.92), cumulative fluid balance >5% of body weight (OR, 0.60; 95% CI, 0.40 to 0.88), and azotemia (OR, 0.57; 95% CI, 0.40 to 0.81). A majority of the excess risk of mortality associated with AKI was attenuated by its fluid volume and metabolic complications, particularly in severe AKI. In addition, this study demonstrated that RRT is associated with a better outcome in patients with AKI-related complications.