Clinical characteristics associated with small airways disease in systemic sclerosis

Objective: Pulmonary manifestations of systemic sclerosis are a major cause of morbidity and mortality. Small airways disease can cause dyspnea and pulmonary function test abnormalities. We aimed to determine the prevalence of small airways disease and describe the characteristics associated with small airways disease in a cohort of systemic sclerosis patients. Methods: We performed a retrospective cohort study of adults with systemic sclerosis who met American College of Rheumatology/European League Against Rheumatism 2013 classification criteria and were evaluated at our institution between November 2000 and November 2015. Patients with prior lung transplantation were excluded. Small airways disease was defined as the presence of one or more of the following: airway-centered fibrosis on surgical lung biopsy, forced expiratory volume at 25-75% <= 50% on pulmonary function tests, and/or high-resolution computed tomography scan of the chest with bronchiolitis, mosaic attenuation, or air trapping on expiratory views. The primary outcome was small airways disease diagnosis. We performed multivariable logistic regression to determine the association of clinical variables with small airways disease. Results: One-hundred thirty-six systemic sclerosis patients were included; 55 (40%) had small airways disease. Compared to those without small airways disease, a significantly greater proportion of those with small airways disease had interstitial lung disease, chronic obstructive pulmonary disease, pulmonary hypertension, and gastroesophageal reflux disease. On multivariable analysis, pulmonary hypertension (odds ratio= 2.91, 95% confidence interval = 1.11-7.65, p-value= 0.03), gastroesophageal reflux disease (odds ratio= 2.70, 95% confidence interval= 1.08-6.79, p-value =0.034), and anti-topoisomerase 1 (anti-Scl-70) antibody positivity (odds ratio=0.42, 95% confidence interval = 0.19-0.93, p-value= 0.033) were associated with diagnosis of small airways disease. Conclusion: Small airways disease is prevalent among systemic sclerosis patients; those with pulmonary hypertension or gastroesophageal reflux disease may have a higher risk of small airways disease.