Recent epidemiologic studies including 85 patients with IPF, and 126 controls demonstrated that high serum and BALF CHI3L1 levels are associated with poor survival: IPF patients with high serum or high BALF CHI3L1 levels had significantly shorter survival than those with low CHI3L1 levels in serum or BALF (Korthagen et al., 2011). Here, CHI3L1 is linked to idiopathic interstitial pneumonia.