Background/Purpose: The connective tissue diseases (CTD) are a group of rheumatologic diseases characterized by inflammation and immune-mediated organ damage including interstitial lung disease (ILD). The reported frequency of ILD associated with CTD (CTD-ILD) is variable, depend on definitions of disease and demographic factors. However, studies of clinical risk factor and serologic biomarkers on CTD-ILD in Korean patients are sparse.The aim of this study is to investigate clinicoserologic biomarkers associated with development, progression, and prognosis of CTD-ILD in Korean patients

Methods: We conducted a single center, a retrospective study including 70 incident patients diagnosed with CTD-ILD and 70 age-, sex-, type of CTD-matched patients without ILD at Kyung Hee University medical center. Clinical information including the time of developing ILD, pulmonary function test, and imaging findings of chest CT were reviewed using medical record. To find serologic biomarkers, serum concentrations of interferon-r-induced protein 10 (IP-10), interleukin (IL)-6, IL-8, IL-10, and matrix metalloproteinase 7 (MMP-7) in patients with CTD-ILD and CTD without ILD were measured using Luminex multiplex bead assay.

Results: Total 140 patient (70 CTD-ILD, 70 CTD without ILD) were enrolled, the mean age of the study group was 63.4 ± 11.2 years, 103 (73.6%) patients were female. To analyze clinical risk factors for developing ILD in CTD, we compared clinical features and laboratory findings between CTD-ILD group and CTD without ILD group. Raynaud`s phenomenon (OR 8.1, 95% CI 2.1-31.2) was the risk factor for developing ILD in CTD in multivariable logistic regression analysis. Rheumatoid arthritis (RA) was the most common type of CTD associated with ILD and idiopathic inflammatory myopathy (IIM)-ILD group had more deteriorated pulmonary functions. Non-specific interstitial pneumonia (NSIP) pattern was the most frequent radiographic pattern (41/70, 58.6%). For analysis of distinctive clinical features according to the onset of ILD, we stratified CTD-ILD patients into three groups: ILD-preceding (12/70, 17.1%), simultaneous (25/70, 35.7%), and CTD-preceding (33/70, 47.1%). In the ILD-preceding group, ILD preceded CTD by 27 months on average, UIP and NSIP had similar proportion. Majority of ILD-preceding group (75%) had worse baseline pulmonary function which required treatment (DLCO < 65%), while 51.5% of in CTD-preceding group did. In CTD-preceding group, NSIP was more common than UIP. Initial DLCO was the risk factor for ILD progression. Serum MMP-7 levels were associated with the developing ILD in CTD patients and had a significant correlation with CT extent score in the present study.

Conclusion: In this study, Raynaud`s phenomenon was a clinical risk factor for ILD in CTD. Patients with preceding ILD prior to CTD had more deteriorated lung function at baseline, and it was associated with poor prognosis. Serum MMP-7 levels had a correlation with ILD development and CT score. Therefore, it is necessary to pay attention to the clinicoserologic biomarkers assoiated with ILD in patients with CTD, this will be beneficial to provide more proper management 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/distinctive-clinical-features-and-biomarkers-of-connective-tissue-disease-associated-interstitial-lung-disease/