CRP and Pleural effusion: The final results showed that the hospitalization time [odds ratio (OR) = 1.584, 95% confidence interval (CI) = 1.082–2.321, P = 0.018], LDH level (OR = 1.022, 95% CI = 1.008–1.036, P = 0.002), CRP level (OR = 1.079, 95% CI = 1.045–1.114, P < 0.001), pulmonary lesions involving two or more lung lobes (OR = 8.997, 95% CI = 1.698–47.682, P = 0.010), and a large amount of pleural effusion (OR = 11.568, 95% CI = 1.767–75.728, P = 0.011) were independent risk factors for delayed radiographic resolution of lobar pneumonia caused by M. pneumoniae in children (P < 0.05) (Table 4).