What is the mortality rate for patients with Acute Kidney Injury (AKI) in the Intensive Care Unit (ICU)?

ICU Mortality in Patients with Acute Kidney Injury

The mortality rate for patients with Acute Kidney Injury (AKI) in the Intensive Care Unit (ICU) is approximately 57.3%, with increasing severity of AKI significantly associated with higher mortality rates. 1

Epidemiology and Prevalence

AKI is extremely common in ICU settings:

• AKI occurs in more than half (57.3%) of ICU patients 1
• Incidence of severe AKI requiring renal replacement therapy (RRT) is 5-8% in general ICU patients, and can exceed 13% in patients with cardiogenic shock 2
• The prevalence is comparable to other critical conditions like acute lung injury/acute respiratory distress syndrome 3

Mortality Rates by AKI Severity

Mortality increases proportionally with AKI severity according to KDIGO staging:

• Stage 1: 1.7-fold increased risk of mortality (not statistically significant) 1
• Stage 2: 2.9-fold increased risk of mortality (p=0.005) 1
• Stage 3: 6.9-fold increased risk of mortality (p<0.001) 1

For patients requiring continuous renal replacement therapy (CRRT):

• Hospital mortality rates reach 69% for patients who develop AKI in the ICU 4
• Long-term mortality increases from 59.7% at hospital discharge to 72.1% at 3 years 5

Risk Factors for Mortality

The primary modifiable risk factors for mortality in ICU patients with AKI include:

• Lack of source control in patients with infections 6
• Inadequate antibiotic therapy in infected patients 6
• Need for mechanical ventilation (3.1-fold increased risk of death) 4

Non-modifiable factors associated with increased mortality:

• Increasing age 5
• Higher severity of illness scores 5
• Use of continuous RRT modalities 5

Long-term Outcomes

Among hospital survivors with AKI requiring RRT:

• Complete renal recovery: 48.4% at 1 year 5
• Incomplete renal recovery: 32.6% at 1 year 5
• Dialysis dependence: 19.0% at 1 year 5

Factors associated with dialysis dependence include:

• Advanced age
• Pre-existing diabetes
• Chronic kidney disease
• Oliguria at the time of RRT initiation 5

Comparison with Other Conditions

• AKI patients have worse outcomes than ESRD patients in the ICU (69% vs 39% mortality) 4
• AKI patients are more likely to require mechanical ventilation than ESRD patients (89% vs 57%) 4
• AKI mortality is higher than that of patients with diabetes but lower than that of patients with heart failure 6

Diagnostic Considerations

AKI is diagnosed using the KDIGO criteria:

• Increase in serum creatinine by ≥0.3 mg/dL within 48 hours, or
• Increase to ≥1.5 times baseline within 7 days, or
• Urine volume <0.5 mL/kg/h for 6 hours 7

Management Implications

Given the high mortality associated with AKI in the ICU:

• Early identification of AKI is crucial
• Prompt treatment of underlying causes (particularly infections)
• Careful consideration of the need for RRT
• Close monitoring of kidney function after discharge, as 47.7% of AKI patients have eGFR <60 mL/min/1.73m² at hospital discharge 1

Pitfalls to Avoid

• Failing to recognize AKI early, as progression to higher stages dramatically increases mortality
• Overlooking source control in patients with infections, as this is a key modifiable risk factor
• Assuming similar outcomes between AKI and ESRD patients in the ICU
• Neglecting post-discharge follow-up, as kidney dysfunction often persists after hospital discharge