Combination of BAL and Computed Tomography Differentiates Progressive and Non-progressive Fibrotic Lung Diseases

Barnett et al discuss their study on the utility of combining baseline BAL and computed tomography (CT) in differentiating progressive and nonprogressive pulmonary fibrosis (PF). The derivation cohort consisted of incident cases of PF for which BAL was performed as part of a diagnostic workup. A validation cohort was prospectively recruited with identical inclusion criteria. Baseline thoracic CT scans were scored for the extent of fibrosis and usual interstitial pneumonia (UIP) pattern. The BAL lymphocyte proportion was recorded. Annualized FVC decrease of >10% or death within 1 year was used to define disease progression. Multivariable logistic regression identified the determinants of the outcome. The optimum binary thresholds (maximal Wilcoxon rank statistic) at which the extent of fibrosis on CT and the BAL lymphocyte proportion could distinguish disease progression were identified. BAL lymphocytosis is rare in patients with extensive fibrosis or a UIP pattern on CT.