Background Interstitial Lung Disease (ILD) associated to Connective Tissue Disease (CTD) represent a challenge for clinicians and researchers because of their significant morbidity and mortality. Although the different types of ILD associated to CTD are often studied and managed as one because of their autoimmune background, there are considerable differences in their etiopathogenesis and therefore it can be assumed that there are differences in their response to treatment (1). Even though previous studies have analyzed the impact of immunosupipression in ILD secondary to sclerodema, additional studies are needed in order to determine the response to treatment of the different forms of ILD associated to CTD (2–3).
Objectives To characterize and analyze the response to treatment of different types of ILD associated to CTD. The primary endpoint is the Functional Vital Capacity (FVC) change at 6 months and 1 year, and secondary endpoints arere the change in Diffusion Capacity of the Lung for Carbon Monoxide and in a 6 Minute Walk Test.
Methods A prospective cohort study is being carried out where all patients who present to the Mayo Clinic Florida pulmonary clinic, age 18 to 80, with established CTD and diagnosed with ILD, and all patients with ILD who meet the criteria for immunologic mediated process, are being followed for a year in order to evaluate the clinical and functional outcomes to treatment. Patients with moderate to severe Pulmonary Hypertension, and active smokers with bronchiolitis pattern are being excluded. Exploratory analysis were performed on the first group of patients enrolled in the study, continuous variables were described with central tendency measures and the mean absolute difference in adjusted 12-month FVC was analyzed between the different types of CTDs using student's t test.
Results Thirteen patients with ILD were enrolled in the study's initial phase. Five of the patients had been diagnosed with an Inflammatory Myopathy (IM), 2 with Rheumatoid Arthritis, 1 with an Undifferentiated Connective Tissue Disease, 1 with Churg-Strauss Syndrome, and one with Systemic Sclerosis. One patient was treated with Rituximab only; 2 with Rituximab and a steroid; 3 with Mycophenolate Mofetil (MMF) only; 2 with steroids, MMF, and Rituximab; 1 with a TNF inhibitor and MMF; 1 with MMF and steroids; 1 with Azathioprine and steroids; and 1 received only steroids. IMs were compared to the rest. At 1 year follow-up FVC mean absolute difference for the IMs demonstrated and improvement of 0.43 while the other CTDs had worsen by a mean of 0.04 (p=0.01). There were no statistical differences at 6 months for all outcomes or at 1 year for DLCO and 6MWT.
Conclusions To our knowledge, this is the first time that a cohort of ILD associated to CTD patients is followed and analyzed after 1 year of treatment. Our results suggest that there is a difference in the response to treatment of ILD depending on the underlying CTD. Specific types of ILD associated to CTD likely benefit from early and aggressive treatment, but longer follow ups and larger studies are needed in order to be able to validate and further understand these pathologies.
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Disclosure of Interest None declared