GDF15 and anemia (phenotype): As showed in Fig 6, a Cox regression model including CIN as a variable showed that after adjusting for age, gender, hydration therapy, primary PCI and anemia, the higher level of GDF-15 (Q4) was significantly associated with an increased risk of all-cause mortality and MACE compared with lower GDF-15 quartiles (Q1, Q2 and Q3) (HR: 8.434, 95% CI: 2.650–26.837, P <0.001; HR: 3.562, 95% CI: 1.658–7.652, P = 0.001).