Association of Age and CKD with Prognosis of Myocardial Infarction

BACKGROUND AND OBJECTIVES: CKD is a well known poor prognostic factor in myocardial infarction (MI). This study evaluated the prognostic significance of CKD, particularly in association with increasing age, in MI patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study was based on a retrospective cohort, the Korean Acute Myocardial Infarction Registry. Patients with a discharge diagnosis of MI were analyzed to investigate the association of CKD with mortality risk according to age. A total of 11,268 patients (mean age 63.0±12.6 years) were included and followed for 1 year. RESULTS: In the full cohort, 26% of patients had CKD (n=2929). The prevalence of CKD was higher with advancing age. Eight hundred sixty-one patients (7.6%) died and the interaction for 1-year mortality between age strata and estimated GFR (eGFR) strata was significant (P<0.001). Within each age category, the absolute 1-year mortality was higher in patients with a low eGFR. However, the adjusted relative mortality risk for a low eGFR was lower with increasing age (adjusted hazard ratio [95% confidence interval] for 1-year mortality at eGFR <30 ml/min per 1.73 m(2): 4.84 [1.93-12.15], 4.53 [2.42-8.47], 3.51 [2.42-5.09], and 3.30 [2.41-4.52] for patients aged <55, 55-64, 65-74, and ≥75 years compared with those with eGFR ≥60 ml/min per 1.73 m(2), respectively). CONCLUSIONS: For all age categories, the overall mortality was significantly higher as eGFR declined. The association of a lower eGFR with mortality was weaker with increasing age, indicating that the prognostic significance of CKD in MI patients is age dependent.