BAL Fluid Cellular Analysis and Radiologic Patterns in Patients With Fibrotic Interstitial Lung Disease

Amanda Grant-Orser; Michael Asmussen; Daniel-Costin Marinescu; Cameron J Hague; Nestor L Muller; Darra T Murphy; Andrew Churg; Joanne L Wright; Amna Al-Arnawoot; Ana-Maria Bilawich; Patrick Bourgouin; Gerard Cox; Celine Durand; Tracy Elliot; Jennifer Ellis; Jolene H Fisher; Derek Fladeland; Gillian C Goobie; Zachary Guenther; Ehsan Haider; Nathan Hambly; James Huynh; Geoffrey Karjala; Nasreen Khalil; Martin Kolb; Jonathon Leipsic; Stacey Lok; Sarah MacIsaac; Micheal McInnis; Helene Manganas; Veronica Marcoux; John Mayo; Julie Morisset; Ciaran Scallan; Tony Sedlic; Shane Shapera; Kelly Sun; Victoria Tan; Alyson W Wong; Boyang Zheng; Christopher J Ryerson; Kerri A Johannson

doi:10.1016/j.chest.2024.07.166

BAL Fluid Cellular Analysis and Radiologic Patterns in Patients With Fibrotic Interstitial Lung Disease

Chest. 2024 Aug 22:S0012-3692(24)04930-4. doi: 10.1016/j.chest.2024.07.166. Online ahead of print.

Authors

Amanda Grant-Orser¹, Michael Asmussen², Daniel-Costin Marinescu³, Cameron J Hague⁴, Nestor L Muller⁴, Darra T Murphy⁵, Andrew Churg⁶, Joanne L Wright⁶, Amna Al-Arnawoot⁷, Ana-Maria Bilawich⁸, Patrick Bourgouin⁹, Gerard Cox¹⁰, Celine Durand¹¹, Tracy Elliot¹², Jennifer Ellis⁴, Jolene H Fisher¹³, Derek Fladeland¹⁴, Gillian C Goobie¹⁵, Zachary Guenther¹², Ehsan Haider⁷, Nathan Hambly¹⁰, James Huynh¹², Geoffrey Karjala¹⁴, Nasreen Khalil⁸, Martin Kolb¹⁰, Jonathon Leipsic⁴, Stacey Lok¹⁶, Sarah MacIsaac¹⁰, Micheal McInnis¹⁷, Helene Manganas¹⁸, Veronica Marcoux¹⁶, John Mayo⁴, Julie Morisset¹⁸, Ciaran Scallan¹⁰, Tony Sedlic⁴, Shane Shapera¹³, Kelly Sun¹³, Victoria Tan¹⁰, Alyson W Wong³, Boyang Zheng¹⁹, Christopher J Ryerson³, Kerri A Johannson²⁰

Affiliations

¹ Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Disease, University of Calgary, Calgary, AB, Canada. Electronic address: amanda.grant-orser@ahs.ca.
² Department of Kinesiology, Vancouver Island University, Vancouver, BC, Canada.
³ Department of Medicine, University of British Columbia, Vancouver, BC, Canada; Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada.
⁴ Department of Radiology, Vancouver General Hospital and University of British Columbia, Vancouver, BC, Canada.
⁵ Department of Radiology, St James' Hospital, Dublin, Ireland.
⁶ Department of Pathology, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
⁷ Department of Radiology, McMaster University, St. Joseph's Healthcare, Hamilton, ON, Canada.
⁸ Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
⁹ Department of Radiology, Radiation Oncology and Nuclear Medicine, University of Montreal, QC, Canada.
¹⁰ Department of Medicine, McMaster University, Hamilton, ON, Canada.
¹¹ Centre de recherche du Centre hospitalier de l'Université de Montréal, Montreal, QC, Canada.
¹² Department of Radiology, University of Calgary, AB, Canada.
¹³ Department of Medicine, University of Toronto, Toronto, ON, Canada.
¹⁴ Department of Medical Imaging, University of Saskatchewan, Saskatoon, SK, Canada.
¹⁵ Department of Medicine, University of British Columbia, Vancouver, BC, Canada; Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, BC, Canada; Department of Medicine, University of Pittsburgh, Pittsburgh, PA.
¹⁶ Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
¹⁷ Department of Medical Imaging, University of Toronto, Toronto, ON, Canada; University Medical Imaging Toronto, Toronto General Hospital, Toronto, ON, Canada.
¹⁸ Department of Medicine, Université de Montréal, Montreal, QC, Canada.
¹⁹ Division of Rheumatology, McGill University, Montreal, QC, Canada.
²⁰ Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Disease, University of Calgary, Calgary, AB, Canada.

PMID: 39179174
DOI: 10.1016/j.chest.2024.07.166

Abstract

Background: BAL cellular analysis is often recommended during the initial diagnostic evaluation of fibrotic interstitial lung disease (ILD). Despite recommendation for its use, between-center heterogeneity exists and supportive data concerning the clinical utility and correlation of BAL findings with radiologic features or patterns remain sparse.

Research question: In patients with fibrotic ILD, are BAL findings associated with radiologic features, patterns, and clinical diagnoses?

Study design and methods: Patients with fibrotic ILD who underwent BAL for diagnostic evaluation and who were enrolled in the prospective Canadian Registry for Pulmonary Fibrosis were re-reviewed in a standardized multidisciplinary discussion (MDD). BAL was categorized according to guideline-recommended thresholds, and using thresholds of lymphocytosis > 20% and neutrophils > 4.5%. High-resolution CT (HRCT) scans were scored (anonymized to clinical data) for specific features and percentage lung involvement. Radiologists classified HRCT scans according to guideline-defined patterns for idiopathic pulmonary fibrosis and fibrotic hypersensitivity pneumonitis; then, MDD diagnoses were assigned, considering all available data.

Results: Bronchoscopy with cellular analysis was performed in 209 of 1,593 patients (13%). Lymphocyte % was weakly negatively correlated with total fibrosis % (r = -0.16, P = .023) but not statistically significantly correlated with ground glass opacity % (r = 0.01, P = .94). A mixed BAL pattern was the most frequent in all radiologic patterns (range, 45%-69%), with a minority classifiable according to BAL guidelines. BAL lymphocytosis appeared with similar frequency across HRCT patterns of fibrotic hypersensitivity pneumonitis (21%) and usual interstitial pneumonia (18%). Only 5% of patients with MDD-based fibrotic hypersensitivity pneumonitis had a guideline-defined isolated lymphocytosis > 15%.

Interpretation: BAL cellular analyses did not significantly correlate with radiologic features, guideline patterns, or MDD-based diagnoses. Ground glass opacities are often interpreted to represent pulmonary inflammation, but were not associated with BAL lymphocytosis in this cohort.

Keywords: BAL; bronchoscopy; guidelines; interstitial lung disease; radiologic patterns.