Early and small changes in serum creatinine concentration are associated to mortality in mechanically ventilated patients

BACKGROUND: Emerging evidence suggests that minor changes in serum creatinine concentration are associated with increased hospital mortality rates. However, whether serum creatinine concentration (SCr) on admission and its change are associated with an increased mortality rate in mechanically ventilated patients is not known. MATERIAL AND METHODS: We have conducted an international, prospective, observational cohort study enrolling adult intensive care unit (ICU) patients under mechanical ventilation (MV). Recursive partitioning (RP) was used to determine the values of SCr at the start of MV (SCr0) and the change in SCr (DeltaSCr, defined as the maximal difference between the value at start of MV [day 0] and the value on MV day 2 at 8:00 AM) that best discriminate mortality. In-hospital mortality, adjusted by a proportional-hazards model, was the primary outcome variable. RESULTS: 2807 patients were included; median age was 59 years and median SAPS II 44. All-cause in-hospital mortality was 44%. The variable that best discriminated outcome was a SCr0 >1.40 mg/dL (mortality 57% vs 36% for patients with SCr0 </=1.40 mg/dL, p>0.001). Among patients with SCr0 </=1.40 mg/dL, DeltaSCr >0.31 discriminated mortality (56% vs 34%, p<0.001). In multivariate analysis, geographical area, advanced age, severity of illness, reason for MV, and cardiovascular and hepatic failure, were also associated to mortality. CONCLUSIONS: Our study suggests that SCr0 >1.40 mg/dL and, in patients with low baseline SCr, a DeltaSCr >0.31 are predictors of in-hospital mortality in mechanically ventilated patients.