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Abstract
Background Anti-CCP2 antibodies are associated with parenchymal lung changes in early RA.
Objectives To examine the association between ACPA fine specificities and parenchymal lung changes in early RA.
Methods Patients with newly diagnosed RA, glucocorticoids and DMARDs-naive, were included. High-resolution computed tomography (HRCT) was performed to assess parenchymal lung changes (ground glass changes, nodules, infiltrates or fibrosis). ImmunoCAP was used to detect RF IgA, RF IgM, anti-CCP2 IgA, anti-CCP2 IgG and ISAC microarray system was used to detect antibodies against 10 citrullinated (Cit) peptidic antigens: CCP-1 (Filaggrin), CEP-1 (α-enolase), Vim 2–17, Vim 60–75 (Vimentin), Fib β 36–52, Fib α 573, Fib α 591, Fib α 36–50, Fib β 60–74, Fib α 621–635 (Fibrinogen). Logistic regression was performed to examine associations between lung changes and autoantibodies, adjusted for age and sex. Due to risk for effect modification of smoking and co-linearity between smoking and Cit peptides, we stratified the cohort according to ever vs. never smokers.
Results A total of 106 patients were included. The mean (SD) age was 57 (14) years. 69% were females; 73% were ever smokers; 70% were RF positive and 69% were positive for anti-CCP2. Parenchymal lung changes were found in 58 patients (54.7%). Higher age [≥65 vs <65, OR (95% CI) =2.5 (1.1–5.9)], pos RF IgA [OR (95% CI) =2.7 (1.2–5.9)], pos CCP2 IgG [OR (95% CI) =2.3 (1.0–5.4)], ever smoking [OR (95% CI) =2.6 (1.1–6.2)] and pack-years above 24 [OR (95% CI) =6.9 (2.0–23.5)], were significant predictors of parenchymal lung changes. Some ACPA fine specificities were associated to parenchymal lung changes in ever smokers (table 1). Having five or more ACPA specificities at the time of diagnosis increased the risk of having lung changes in ever smokers by 6.6 times (table 1).
Association between ACPA fine specificities and parenchymal lung changes according to smoking status
Conclusions RF IgA, anti-CCP2 IgG, antibodies to Cit Fib and Cit Vim peptides were strongly associated to parenchymal lung changes in ever smokers with early RA. The more ACPA fine specificities, the higher the risk of parenchymal lung changes.
Disclosure of Interest None declared