Cell profiles of bronchoalveolar lavage fluid as prognosticators of idiopathic pulmonary fibrosis/usual interstitial pneumonia among Japanese Patients.

Background: The role of bronchoalveolar lavage fluid (BALF) cell profiles in predicting the clinical outcome of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP) is still under discussion.

Objective: To determine whether BALF cell profiles affect the survival of patients with UIP diagnosed by surgical lung biopsy/autopsy at the early stage of IPF.

Methods: This hospital-based retrospective cohort study used 81 Japanese patients with histologically proven IPF/UIP who underwent BAL examination. The BALF samples were obtained from non-current smokers: NCS (n = 41) and current smokers: CS (n = 40). The Kaplan-Meier and Cox's proportional hazard methods were used to estimate the survival and evaluate the risk ratio for death in the two groups. To detect the multicollinearity, a stepwise regression was employed.

Results: A slight increase in the absolute numbers of BALF neutrophils tended to relate to a decrease in the relative risk for death in NCS patients and CS patients in the univariate analysis. In stepwise regression, the increase in percent vital capacity and the increase in the BALF CD4/CD8 ratio in NCS was detected as a favorable predictor, while increased BALF cells affected the results due to chronic smoking in CS.

Conclusions: Based on the study bias of the biopsy-proven IPF/UIP patients at stable stages, an independent variable indicating a favorable outcome was an increased BALF CD4/CD8 ratio in NCS patients, while it was difficult to identify definite prognosticators in CS patients.