Small acute increases in serum creatinine are associated with decreased long-term survival in the critically ill.

RATIONALE: Long-term outcomes after acute kidney injury (AKI) are poorly described.
OBJECTIVES: We hypothesized that one single episode of minimal (stage 1) AKI is associated with reduced long-term survival compared with no AKI after recovery from critical illness.
METHODS: A prospective cohort of 2,010 intensive care unit (ICU) patients admitted to the ICU between years 2000 and 2009 at a provincial tertiary care hospital. Development of AKI was determined according to the KDIGO classification and mortality up to 10 years after ICU admission was recorded.
MEASUREMENTS AND MAIN RESULTS: Of the 1,844 eligible patients, 18.4% had AKI stage 1, 12.1% had stage 2, 26.5% had stage 3, and 43.0% had no AKI. The 28-day, 1-year, 5-year, and 10-year survival rates were 67.1%, 51.8%, 44.1%, and 36.3% in patients with mild AKI, which was significantly worse compared with the critically ill patients with no AKI at any time (P < 0.01). The unadjusted 10-year mortality hazard ratio was 1.53 (95% confidence interval, 1.2-2.0) for 28-day survivors with stage 1 AKI compared with critically ill patients with no AKI. Adjusted 10-year mortality risk was 1.26 (1.0-1.6). After propensity matching stage 1 AKI with no AKI patients, mild AKI was still significantly associated with decreased 10-year survival (P = 0.036).
CONCLUSIONS: Patients with one episode of mild AKI have significantly lower long-term survival rates than critically ill patients with no AKI. Close medical follow-up of these patients may be warranted and mechanistic research is required to understand how AKI influences long-term events.