The most common extra-articular manifestation of rheumatoid arthritis (RA) is interstitial lung disease (ILD). RA related ILD (RA-ILD) is associated with significant morbidity and mortality. The main objective of this study was to determine the correlation between the rheumatoid factor (RF) serotypes and the severity of RA-ILD based on computed tomography (CT) findings. We recruited a total of 100 RA patients who were tested for IgA RF, IgG RF and IgM RF and had high resolution CT chest performed. Seventy-two patients had ILD changes on HRCT of the chest and were included in this study. We found that the the CT scores for ground glass showed significant positive correlation with disease duration and IgA RF levels whereas the fibrosis scores had significant relationship with multiple clinical covariates i.e age, disease duration, IgA RF levels, IgG RF levels and anti-CCP levels. On multivariate analysis, only IgA levels remained significantly (p<0.05, standardized beta coefficient = 0.604) associated with the ground glass scores. Regarding the fibrosis scores, IgA RF levels and age were independent predictors based on multivariate analysis after adjusting for confounders, with p scores of <0.05 and 0.02, respectively. In conclusion, the IgA RF was the only serotype which was independently associated with the severity of RA-ILD.
Correlation of Rheumatoid Factor Serotypes and Computed Tomography Findings in Rheumatoid Arthritis Related Interstitial Lung Disease
Abstrak
Manifestasi ekstra artikular rheumatoid arthritis (RA) adalah penyakit paru-paru interstisial (ILD). RA berkaitan ILD (RA-ILD) dikaitkan dengan morbiditi dan mortaliti yang ketara. Objektif utama kajian ini adalah untuk menentukan korelasi antara serotype faktor rheumatoid (RF) dan keterukan RA-ILD berdasarkan penemuan tomografi komputer (CT). Kami telah mendapatkan sejumlah 100 pesakit RA yang diuji untuk IgA RF, IgG RF dan IgM RF dan melalui imbasan CT dada resolusi tinggi. Tujuh puluh dua pesakit mempunyai perubahan ILD pada HRCT dada dan dimasukkan ke dalam kajian ini. Kami mendapati bahawa skor CT bagi “ground glass” menunjukkan korelasi positif yang signifikan dengan tempoh penyakit dan paras IgA manakala skor fibrosis mempunyai hubungan yang signifikan dengan kovariat-kovariat; usia, tempoh penyakit, tahap IgA, tahap IgG dan tahap anti-CCP. Pada analisis multivariat, hanya tahap IgA sahaja yang ketara (p<0.05, pekali beta standard = 0.604) yang dikaitkan dengan skor “ground glass”. Bagi skor fibrosis, tahap dan umur IgA adalah prediktor bebas berdasarkan analisis multivariat, dengan skor <0.05 dan 0.02, masing-masing. Sebagai kesimpulan, IgA RF adalah satu-satunya serotype yang secara bebas dikaitkan dengan keterukan RA-ILD.
Kata kunci
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