NPPB and anemia (phenotype): As shown in Tables 1 and 2, we can see that age, age-adjusted Charlson comorbidity index (ACCI), fracture type, preoperative waiting time, respiratory disease, acute kidney injury, history of heart disease (chronic heart failure excluded), anemia at admission, ASA ≥ 3, left ventricular ejection fraction (LVEF), BNP value at admission, Hb value at admission, blood transfusion before the operation, and serum potassium value at admission were statistically significant factors (P < 0.05).