Aims: 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.
Methods and results: 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 (Pinteraction <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.
Conclusion: Acute kidney injury is associated with worse long-term outcomes after MI. This effect is modified by baseline CKD status.
Keywords: Discharge medications; Kidney injury; Myocardial infarction; Outcomes.
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