CRP and chronic obstructive pulmonary disease: In terms of the multivariate logistic regression analysis, S1P (OR: 2.00, 95% IC: p < 0.005) and CRP (OR: 2.68, 95% IC: 1.71–5.77, p < 0.001) were significant factors in differentiating between the COPD with pneuomina group and the AECOPD group.