Dyspnea, percentage of CD4 + T-lymphocytes, and percentage of monocytes at admission were strong predictors of AE-IPF, with hazard ratios of 2.28 (95% confidence interval 1.43 to 3.70), 0.96 (0.94 to 0.97), and 0.92 (0.86 to 0.99), respectively (Table 2). This evidence concerns the gene CD4 and idiopathic pulmonary fibrosis.