Bronchoalveolar Lavage Lymphocytosis and Early Glucocorticoid Response: A Prospective Study of 150 Subjects With Interstitial Lung Disease

Background and Objective Bronchoalveolar lavage lymphocyte percentage (BLP) is considered a prognostic marker for interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). Its association with an early glucocorticoid response (EGR) has not been studied systematically. We aimed to assess the association of BLP and other factors with EGR. Methods We prospectively enrolled subjects with non‐IPF ILDs and treated them with glucocorticoids. We defined EGR as a composite response in symptoms and pulmonary function tests 2 months after glucocorticoid initiation. Cases were those with EGR (responders), while non‐responders (without EGR) formed the controls. The primary exposure was the BLP expressed on an ordinal scale: 0%–19%, 20%–29%, 30%–39%, ≥ 40%. Confounders included age, sex, body mass index, smoke exposure, %pred FVC, symptom duration, inflammatory and/or fibrotic phenotype on chest computed tomography. We also assessed factors associated with progressive disease at 6 months. Results We included 150 subjects (mean age, 51.2 years; 39% men); 73% had either hypersensitivity pneumonitis or connective tissue disease‐related ILD. One hundred and thirty‐one subjects (69 responders; 62 non‐responders) followed up at 2 months. The BLP (adjusted odds ratio [aOR], 1.64; 95% confidence intervals [CI], 1.03–2.63; p = 0.04) and symptom duration (aOR, 0.60; 95% CI, 0.40–0.92; p = 0.02) were independently associated with EGR. A BLP < 20% (aOR, 4.37; 95% CI, 1.37–13.96; p = 0.01) and history of smoke exposure (aOR, 4.59; 95% CI, 1.25–16.91; p = 0.02) independently predicted progressive disease at 6 months. Conclusion Higher BLPs and shorter symptom duration were associated with EGR, while BLP < 20% and smoke exposure predicted progressive disease despite glucocorticoid treatment.