Interstitial Lung Disease in Mixed Connective Tissue Disease

Screening and Monitoring

All patients diagnosed with Mixed Connective Tissue Disease (MCTD) should undergo screening with high-resolution computed tomography (HRCT) and pulmonary function tests (PFTs) including spirometry and diffusing capacity for carbon monoxide (DLCO) at diagnosis 1, 2
For patients with an SSc phenotype, follow-up should include PFTs every 6 months 2 and annual HRCT for the first 3-4 years after diagnosis 1
Risk factors for MCTD-associated ILD include esophageal dysfunction, dysphagia, Raynaud's phenomenon, anti-Smith or anti-Ro-52 antibodies, rheumatoid factor, and no history of arthritis 1

For MCTD-associated ILD, mycophenolate is the preferred first-line therapy 3, 4
Additional first-line options include azathioprine and tocilizumab 3, 4
Short-term glucocorticoids (≤3 months) may be used, but should be used cautiously in patients with an SSc phenotype due to increased risk of renal crisis 3, 4

Signs of fibrosis on HRCT are associated with increased mortality, with one study showing a mortality rate of 20.8% in patients with severe pulmonary fibrosis compared to 3.3% in those with normal HRCT 1
Although ILD in MCTD is typically modest in extent, nearly 50% of patients will experience progression 1
Progression is generally slow but may continue for several years after diagnosis 1