Prognostic Value of Bronchoalveolar Lavage in Systemic Autoimmune Rheumatic Diseases-Associated Interstitial Lung Disease
Maximilian Robert Gysan, Kastriot Kastrati, Svitlana Pochepnia, Helmut Prosch, Antje Lehmann, Silvia Lee, Andreas Renner, Christina Bal, Anastasia Papaporfyriou, Christopher Milacek, Lukasz Antoniewicz, Seda Metekol, Markus Kramer, Lisa John, Zahra Kargarpour, Iris Aykara, Peter Weber, Karolina Anderle, Hans Peter Kiener, Michael Bonelli, Daniel Mrak, Daniel Aletaha, Ahmed El-Gazzar, Daniela Gompelmann, Marco Idzko, Helga Lechner-RadnerBackground: Systemic autoimmune rheumatic diseases-associated interstitial lung disease (SARD-ILD) presents with varied disease courses, emphasizing the need for reliable predictors of progression. The prognostic utility of bronchoalveolar lavage (BAL) in SARD-ILD remains underexplored. The objective of this study was to evaluate the role of BAL fluid lymphocyte count in predicting disease progression in patients with SARD-ILD. Methods: This observational study included patients with SARD-ILD undergoing BAL as part of their diagnostic workup. Disease progression was defined as either Forced vital capacity (FVC) decrease >10%, two out of the following three criteria within two years: FVC decrease of 5–10%, worsening symptoms, increased fibrosis on imaging, or any of the following: escalation of treatment, Interstitial lung disease (ILD) exacerbation, lung transplantation, or disease-specific mortality. Logistic regression identified predictors of progression. Time-to-progression was assessed using Kaplan–Meier survival curves. The optimal BAL lymphocyte threshold for predicting progression was identified using the Youden Index and the Wilcoxon method. Results: We identified 89 patients, of whom 30 (33.7%) had progressive disease. Progressors had a significantly higher BAL lymphocyte count compared to non-progressors (31.6 ± 24.8% vs. 14.3 ± 16.5%, p < 0.001). BAL lymphocyte proportion was significantly and independently associated with disease progression (odds ratio, 1.05; 95% confidence interval 1.02–1.07; p < 0.01). A lymphocyte count above 9 percent was associated with a markedly increased risk of disease progression (odds ratio, 13.14; 95% confidence interval, 4.20–51.98; p < 0.01). Conclusions: BAL lymphocyte count was associated with a higher likelihood of progression in SARD-ILD. BAL assessment may help identify patients at increased risk of disease progression. However, these findings should be considered exploratory and require validation in larger prospective studies and across individual SARD-ILD subtypes.