Acute Kidney Injury Definition and In-Hospital Mortality in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction

Abstract

Background: Acute kidney injury (AKI) has been associated with increased mortality in ST-segment elevation myocardial infarction. We compared the mortality predictive accuracy of the 3 AKI definitions used most widely for patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Methods and results: We included 3771 patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention at 2 Italian hospitals. AKI incidence was evaluated according to creatinine increases of ≥25% (AKI-25), ≥0.3 mg/dL (AKI-0.3), and ≥0.5 mg/dL (AKI-0.5). The primary end point was in-hospital mortality. Overall, 557 (15%), 522 (14%), and 270 (7%) patients developed AKI-25, AKI-0.3, and AKI-0.5, respectively (P<0.01). All AKI definitions independently predicted in-hospital mortality (adjusted odds ratio 4.9 [95% CI 3.1-7.8], 5.4 [95% CI 3.3-8.6], and 8.3 [95% CI 5.1-13.3], respectively; P<0.01 for all). At receiver operating characteristic analysis, the addition of each AKI definition to combined clinical predictors of mortality (age, sex, left ventricular ejection fraction, admission creatinine, creatine kinase-MB peak) found at stepwise analysis significantly improved mortality prognostication (area under the curve increased from 0.89 for clinical predictor combination alone to 0.92 for AKI-25, 0.92 for AKI-0.3, and 0.93 for AKI-0.5; P<0.01 for all). At reclassification analysis, AKI-0.5 added to clinical predictors, provided the highest score in mortality (net reclassification improvement +10% versus AKI-0.3 [P=0.01] and +8% versus AKI-25 [P=0.05]).

Conclusions: Each AKI definition significantly improved the mortality prediction beyond major clinical variables. AKI-0.5 showed a mortality discrimination advantage, suggesting it should be the preferred definition in studies addressing ST-segment elevation myocardial infarction and focusing on short-term mortality.

Keywords: acute kidney injury; serum creatinine concentration.