Raynaud's phenomenon and anti-nuclear antibody are associated with pulmonary function decline in patients with dermatomyositis and polymyositis.

Objectives: To identify factors associated with deterioration of pulmonary function with disproportional decline in diffusing capacity for carbon monoxide (DLCO) relative to forced vital capacity (FVC) in patients with dermatomyositis (DM) and polymyositis (PM).

Methods: This retrospective cohort study included patients with DM and PM, in whom serial pulmonary function tests were available. Changes in FVC and DLCO over time were estimated using a linear mixed-effects model.