Abstract: Objective To investigate the correlation of type Ⅳ collagen (ⅣC) and amino terminal peptide of type Ⅲ procollagen (PⅢNP) with pulmonary function and acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) in the elderly patients with IPF. Methods From January 2018 to January 2022, 89 elderly patients with IPF (IPF group) and 42 elderly receiving health examination (control group) in our hospital were enrolled in this study. The levels of serum ⅣC, PⅢNP and pulmonary function were detected, and the incidence of AE-IPF was recorded within 1 month follow-up after discharge. Pearson correlation coefficient was used to describe the correlation between ⅣC, PⅢNP and pulmonary function. Multivariate Logistic regression analysis was used to analyze the risk factors of AE-IPF. Receiver operating characteristic curve (ROC) was used to analyze the value of ⅣC and PⅢNP in predicting AE-IPF. Results The serum levels of ⅣC and PⅢNP in IPF group were higher than those in control group (P<0.01), and the levels of FEV1, FVC, FEV1/FVC and MVV in IPF group were lower than those in control group (P < 0.01). ⅣC and PⅢNP were both negatively correlated with FEV1, FVC, FEV1/FVC and MVV (P < 0.01). During the follow-up period, 49 cases of AE-IPF occurred. High levels of ⅣC, PⅢNP and infection were the risk factors for AEI-IPF (P<0.05). The areas under the curve of ⅣC and PⅢNP in predicting AE-IPF were 0.718 and 0.768, and the area under the curve of the combination of ⅣC and PⅢNP in diagnosing AE-IPF was 0.940, which was greater than that of ⅣC and PⅢNP alone (Z=3.941,2.991, all P<0.05). Conclusions The serum levels of ⅣC and PⅢNP are significantly increased in the patients with IPF, which are related to the decline of pulmonary ventilation function and the occurrence of AE-IPF, and can be used as predictive markers of AE-IPF.

Key words: idiopathic pulmonary fibrosis, type Ⅳ collagen, type Ⅲ procollagen, N-terminal propeptide, lung function, acute exacerbation