Tumor Necrosis Factor Blockade Fails to Improve Small Airway Obstruction in Rheumatoid Arthritis

Objective: To determine whether tumor necrosis factor (TNF) blockade improves small airway obstruction in rheumatoid arthritis (RA) patients without apparent respiratory symptoms.Methods: Pulmonary function tests were performed before and one year after TNF blockade therapy in 29 RA patients without apparent respiratory symptoms. As a control, pulmonary function was examined at a one-year interval in 27 RA patients with conventional disease-modifying antirheumatic drugs (DMARDs) alone. Small airway obstruction was diagnosed when one of maximal mid-expiratory flow rate (MMEF), forced expiratory flow at 50% (FEF50) or 75% (FEF75) of the vital capacity was decreased to less than 60%, 55%, or 45% of predicted values, respectively.Results: Small airway obstruction was found in 62.5% of RA patients. No differences were found in age, sex, disease duration, or disease activities. TNF inhibitors dramatically reduced disease activities. However, TNF inhibitors failed to improve small airway obstructions but worsened them.Conclusions: TNF blockade fails to improve small airway obstruction, suggesting that TNF-independent pathways play important roles in the development of small airway obstruction in RA.