Fig. 2.

Spline function plots of the association of perioperative hemoglobin decrease (ΔHb) with the composite outcome including in-hospital mortality, myocardial infarction, stroke, and acute kidney injury. The association was assessed in cardiac surgery patients (A) without or (B) with preoperative anemia. Solid lines indicate odds ratios (ORs), while blue-shaded areas indicate 95 % confidence intervals. Dashed lines indicate the reference condition. All models were adjusted for sex, age (<65 or ≥ 65 year), body mass index (<18.5, 18.5–24.9, 25.0–29.9 or ≥ 30.0 kg/m²), current smoking, ASA classification, comorbidities (see section 3.2 of the main text), preoperative hemoglobin level, left ventricular function, type of surgery, cardiopulmonary bypass duration, and perioperative red blood cell transfusion.