Fig. 2

The adjusted smoothed curves of PBT and LOS. A threshold, nonlinear correlation between PBT and LOS, as evidenced by our generalized additive model. The red curve (middle) refers to a predicted value, and the blue curves (both sides) refer to the 95% CIs. Adjustment AGE; BMI; Gender; Hemoglobin; Primary diagnosis; ASA; Cr; Anesthesia; surgical method; CCI. The turning point (K) of the curve in Model II was 1.5 units