Background: The prognostic value of BAL fluid cell count differential in patients with idiopathic pulmonary fibrosis (IPF) is unknown. We hypothesized that baseline BAL fluid cell count differential (ie, elevated levels of neutrophils and eosinophils, or reduced levels of lymphocytes) would predict higher mortality among persons with IPF.
Methods: We evaluated the association of BAL fluid cell count differential and mortality among 156 persons with surgical lung biopsy-proven IPF who underwent bronchoscopy with BAL and cell count differential measurements at presentation. Vital status was obtained among all participants. Cox regression analysis evaluated the association of BAL fluid cell count differential and mortality.
Results: After controlling for known clinical predictors of mortality, we found that each doubling of baseline BAL fluid neutrophil percentage was associated with a 30% increased risk of mortality (adjusted hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.01 to 1.62; adjusted p = 0.04) in the first year after presentation. We observed no association with BAL fluid lymphocyte percentage and mortality (adjusted HR per doubling, 0.99; 95% CI, 0.76 to 1.29; p = 0.93) or eosinophil percentage and mortality (adjusted HR per doubling, 0.99; 95% CI, 0.69 to 1.40; p = 0.95).
Conclusions: Increased BAL fluid neutrophil percentage is an independent predictor of early mortality among persons with IPF. Alternatively, BAL fluid lymphocyte and eosinophil percentages were not associated with mortality. The clinical utility of BAL at the time of diagnosis of IPF should be reconsidered.