Figure 5From: Ageing and smoking contribute to plasma surfactant proteins and protease imbalance with correlations to airway obstruction Receiver operating characteristic curves of SP-A, SP-D, MMP-9 and TIMP-1 in plasma (A, B, C and D, respectively) obtained from patients with COPD, young and middle aged/elderly smokers and the controls. Values in parentheses indicate 95% confidence intervals for the area under the curve (AUC).Back to article page