CRP and chronic obstructive pulmonary disease: Following additional adjustments for significant COPD risk factors (Model 2), the AUC values were as follows: CALLY index at 0.831 (95% CI 0.806–0.856), CLR at 0.831 (95% CI 0.806–0.855), NLR at 0.830 (95% CI 0.805–0.855), and CRP at 0.829 (95% CI 0.804–0.854).