Incremental contribution of bronchoalveolar lavage fluid data to multidisciplinary discussion of interstitial lung disease

BACKGROUND: Multidisciplinary discussion (MDD) integrating clinical, radiological, and laboratory information is considered the reference standard for the diagnosis of interstitial lung disease (ILD). Bronchoalveolar lavage fluid (BALF) analysis is recommended in several diagnostic algorithms, but its incremental contribution during multidisciplinary evaluation remains incompletely characterized. In this study, we aimed to assess the impact of BALF findings on diagnostic consensus and confidence during MDD for suspected ILD. METHODS: In this cross-sectional study, patients with suspected ILD at a tertiary referral center who remained without a definitive diagnosis after clinical evaluation and high-resolution computed tomography (HRCT) underwent bronchoscopy with BALF collection (n = 29). Blinded pulmonologists and radiologists evaluated each case using a sequential four-step framework: (1) radiological assessment; (2) radiological assessment with clinical data; (3) multidisciplinary discussion without BALF information; and (4) multidisciplinary discussion including BALF results. Interobserver agreement was assessed using Fleiss' kappa, and diagnostic confidence was recorded at each stage. RESULTS: Diagnostic agreement increased across the sequential evaluation steps (Fleiss' κ: 0.056, 0.565, 0.905, and 0.965, respectively; p < 0.001). Consensus diagnoses were achieved in 24 cases after MDD without BALF and in 27 cases following incorporation of BALF findings. The proportion of evaluations with high diagnostic confidence (≥ 90%) increased from 3.4% before BALF availability to 20.7% after its inclusion. CONCLUSION: Within a multidisciplinary diagnostic framework for ILD, BALF information were associated with improved diagnostic consensus and increased clinician confidence. BALF may therefore serve as a complementary diagnostic tool in the multidisciplinary assessment of ILD, particularly in cases that remained uncertain after clinical and radiological evaluation.