Association of acute kidney injury and chronic kidney disease with processes of care and long-term outcomes in patients with acute myocardial infarction

To examine the association of acute kidney injury (AKI) with long-term outcomes after myocardial infarction (MI), and evaluate whether effect modification is present according to baseline chronic kidney disease (CKD) status.

ACTION Registry records from 2008 to 2012 were linked to Medicare claims data, creating a cohort of 76 500 acute MI patients aged ≥ 65 years who survived to hospital discharge. Mild, moderate, and severe AKI were defined as changes in creatinine from baseline to peak of 0.3 to < 0.5, 0.5 to < 1.0, and ≥ 1.0 mg/dL, respectively. Stage 3, Stage 4, and Stage 5 CKD were defined as estimated glomerular filtration rates of 30–59, 15–29, and <15 mL/min/m², respectively. Cox proportional hazards modelling was used to examine associations of AKI with long-term outcomes. The prevalence of baseline CKD was: Stage 3 (41.2%), Stage 4 (6.7%), and Stage 5 (1.0%). The incidence of AKI was: mild (7.5%), moderate (6.0%), and severe (3.0%). A significant interaction of AKI with baseline CKD was observed for 1-year mortality (P_interaction <0.001). Acute kidney injury was associated with worse multivariable-adjusted 1-year mortality among individuals without CKD: mild AKI [hazard ratio (HR): 1.33, 95% confidence interval (CI): 1.22–1.49], moderate AKI (HR:1.66, 95% CI: 1.46–1.89), and severe AKI (HR: 2.87, 95% CI: 2.41–3.43). An attenuation of this effect was noted with advancing stages of baseline CKD such that among patients with Stage 5 CKD, AKI was not associated with 1-year mortality.

Acute kidney injury is associated with worse long-term outcomes after MI. This effect is modified by baseline CKD status.