Lung Auscultation for Detecting Interstitial Lung Disease in Patients with Newly Diagnosed Systemic Sclerosis: Retrospective Cohort Study

Background/Objectives: Interstitial lung disease (ILD) occurs commonly in systemic sclerosis (SSc) and is the leading cause of mortality. There are limited data on the accuracy of lung auscultation in identifying the presence of ILD in patients with SSc. Methods: We retrospectively identified patients with newly diagnosed SSc who had documented lung auscultation findings and chest high-resolution computed tomography (HRCT) available for review. Diagnoses were made by rheumatologists at Mayo Clinic, Rochester, Minnesota, USA over a 4-year period. Pulmonary function measurements included lung volumes, spirometry, and single-breath diffusing capacity. Results: Among 151 patients with SSc (median age, 62 years), 72.2% were female and 55.0% were never smokers. Limited cutaneous SSc was the most common phenotype (67.3%). Seventy (46.4%) patients were evaluated by pulmonologists. There was evidence of ILD by HRCT in 69 patients (45.7%); the most common pattern of ILD was fibrotic nonspecific interstitial pneumonia (59.2%). Respiratory symptoms were present in 46.4% of those with ILD compared to 15.9% among those without. The sensitivity and specificity for crackles heard by rheumatologists in detecting ILD were 50.7% and 97.6%, respectively; for pulmonologists, 71.4% and 85.7%, respectively. Presence of crackles was associated with high positive predictive values (94.6% for rheumatologists vs. 92.1% for pulmonologists, respectively); negative predictive values were moderate (70.2% vs. 56.3%, respectively). Crackles correlated with lower pulmonary function measures but did not differ across ILD patterns. Conclusions: Detection of crackles on lung auscultation appears to be a specific and moderately sensitive indicator of ILD (often asymptomatic) in patients with newly diagnosed SSc. The presence of crackles correlates with worse pulmonary function but may be absent in early ILD.