Receiver operating characteristics curve (ROC) analysis of C-reactive protein, albumin, and lymphocyte (CALLY) index, C-reactive protein to lymphocyte ratio (CLR), neutrophil-to lymphocyte ratio (NLR), leukocytes, monocytes, and C-reactive protein in predicting the risk of chronic obstructive pulmonary disease (COPD) onset in a middle-aged and older population in the United States. This evidence concerns the gene CRP and chronic obstructive pulmonary disease.