Predictors for bronchoalveolar lavage recovery failure in diffuse parenchymal lung disease

Bronchoalveolar lavage (BAL) plays a role in the diagnosis of diffuse parenchymal lung diseases (DPLD); however, poor BAL fluid (BALF) recovery results in low diagnostic reliability. BAL is relatively safe, but its indications should be carefully considered in patients with risks. Therefore, estimating the likelihood of recovery failure is helpful in clinical practice. This study aimed to clarify predictors of BALF recovery failure and to develop its simple-to-use prediction models. We detected the predictors applying a logistic regression model on clinical, physiological, and radiological data from 401 patients with DPLD (derivation cohort). The discrimination performance of the prediction models using these factors was evaluated by the c-index. In the derivation cohort, being a man, the forced expiratory volume in one second/forced vital capacity, and a BAL target site other than right middle lobe or left lingula were independent predictors. The c-indices of models 1 and 2 that we developed were 0.707 and 0.689, respectively. In a separate cohort of 234 patients (validation cohort), the c-indices of the models were 0.689 and 0.670, respectively. In conclusion, we developed and successfully validated simple-to-use prediction models useful for pulmonologists considering BAL indications or target sites, based on independent predictors for BALF recovery failure.