Abstract 4175: Duration of Acute Kidney Injury and Long-term Survival Following Cardiac Surgery
Background: Acute kidney injury (AKI) following cardiac surgery is associated with worse complications. However, it is not known how adverse long-term consequences vary according to the duration of AKI. We hypothesized that longer durations of AKI are associated with an increased risk of long-term mortality compared with short episodes of AKI independent of AKI.
Methods: We prospectively enrolled 4,987 cardiac surgery patients from 2002 through 2007 with serum creatinine (SCr) collection at a medical center in northern New England. Patients with dialysis were excluded (N=70). AKI was defined as a ≥0.3 (mg/dL) or ≥50% increase in SCr from baseline. Duration of AKI was defined by the number of days AKI was present and categorized by: no AKI, AKI for 1–2, 3– 6 and ≥7 days. Univariate and multivariate regression, Kaplan Meier, and Cox’s proportional hazard modeling were conducted to evaluate long-term mortality.
Results: 39% of patients developed AKI. Long-term mortality was significantly different at 5 years by AKI duration (p<0.001). The proportion of patients, adjusted hazard ratios (HR) and 95% confidence intervals for AKI duration (no AKI as referent) were: 1–2 days (18%, HR 1.66; 1.32–2.09), 3– 6 days (11%, HR 1.94; 1.51–2.49), ≥7 days (9%, HR 3.40; 2.73– 4.25). This graded relationship of duration of AKI with long-term mortality persisted when patients who died during hospitalization were excluded from analysis (p<0.001).
Conclusions: The duration of AKI after cardiac surgery is directly proportional to long-term mortality and has important implications in patient care and can aid clinicians in evaluating the risk of in-hospital and post-discharge death.