Figure 4.

Receiver-operator characteristic (ROC) curve for the ability of IL-8 to predict prolonged mechanical ventilation after cardiopulmonary bypass (CPB). Prolonged mechanical ventilation was defined as more than 24 hours of ventilation. Interleukin-8 levels were log-transformed because they were abnormally distributed. The area under the ROC curve is 0.89, with a Hosmer-Lemeshow goodness-of-fit P value of 0.75, demonstrating that increased serum IL-8 at 2 hours is an excellent predictor of prolonged mechanical ventilation in patients after CPB.