Acute Kidney Injury in the German EuroAspire IV Cohort: A Risk Factor for Rehospitalization

Background: Acute kidney injury (AKI) is a serious complication of cardiovascular diseases. Even a slight increase of serum creatinine (SCr) is associated with a higher risk of mortality, morbidity, development of chronic kidney disease (CKD) and congestive heart failure (HF). In patients undergoing coronary artery bypass grafting (CABG) surgery, re-hospitalization and mortality rates increase among those suffering from postoperative AKI even in a mild stage as defined by current nephrology (KDIGO) guidelines. Yet, it is unknown whether AKI predicts re-hospitalization rates in EuroAspire IV patients, surviving acute myocardial infarction (MI) or acute coronary syndrome (ACS).

Methods: We used data of the German subset (n = 536) of the European wide EUROASPIRE IV multicenter study and all n = 359 patients experiencing ACS or MI during the EUROASPIRE IV index event (October 2011- March 2012) were analyzed. Patients were either treated conservatively, by percutaneous intervention or by CABG surgery. The KDIGO AKI definition was used to determine the incidence of AKI - an increase of serum creatinine (SCr) by ≥ 0.3mg/dl within 48hours. The baseline study visit was performed 6 months to 3 years after the hospital discharge. Determinants for re-hospitalization between hospital discharge and the study visit were identified by a multivariate regression model.

Results: AKI occurred in 90 patients (25%) during the index hospitalization. Patients suffering from AKI tended to be older, were more likely to receive CABG surgery and had a history of HF (all p < 0.05). CKD at admission and diabetes were no risk factors for AKI during the index hospital stay (p > 0.05). Between hospital discharge and the study visit, 84 patients were re-hospitalized due to cardiovascular events, such as myocardial ischemia or infarction, angina, CABG surgery, PCI, stroke, TIA or due to heart failure. CABG surgery and AKI during index hospitalization showed an independent association with re-hospitalization until the follow-up visit (OR(CI95%) 2.35 (1.03–5.36) and 2.03 (1.01–4.05) respectively).

Discussion: In the present cohort, AKI and CABG were independent predictors of re-hospitalization after a coronary event. Neither age, nor kidney function at hospital admission nor the history of diabetes were determinants of re-hospitalization.

Conclusion: AKI is an independent risk factor of re-hospitalization in patients hospitalized for acute coronary syndrome.