Clinical role of bronchoalveolar lavage in dermatomyositis-associated interstitial lung disease

OBJECTIVE: To investigate the role of bronchoalveolar lavage (BAL) in DM-associated interstitial lung disease (ILD). METHODS: We retrospectively reviewed the medical records of patients with DM-ILD who underwent bronchoscopy between October 2015 and September 2019. We then collated clinical features, laboratory data and bronchoscopy findings. The follow-up study was terminated on the 1 May 2020. RESULTS: A total of 113 DM-ILD patients were included in this study, including 27 patients with acute/subacute interstitial pneumonia (A/SIP) and 86 patients with chronic interstitial pneumonia (CIP). The A/SIP group had significantly lower proportions of lymphocytes and eosinophils in the bronchoalveolar lavage fluid (BALF) than the CIP group, but had a significantly higher proportion of neutrophils. Pathogens were discovered in BALF from 28 (24.8%) patients. Twenty-five (22.1%) patients commenced or changed antibiotic therapy on the basis of their bronchoscopy results. Lymphopenia and intensive care unit care were significantly associated with pathogen-positive BALF findings. Complications of bronchoscopy occurred in nine (8.0%) patients; fever (5.3%) was the most common complication. Twenty-five deaths (25/106, 23.6%) were observed during a mean follow-up of 22 months. Age, A/SIP and anti-MDA5 antibody were identified as independent predictors of a poor outcome, while mechanic's hands was an independent protective factor. However, cellular and pathogen findings in BALF had no significant influence on 30-day or overall mortality. CONCLUSION: Bronchoscopy is a relatively useful instrument to evaluate ILD in patients with DM, and BAL can improve the diagnosis of infection. However, cellular and pathogen findings from BALF had no significant influence on prognosis.