Background Rheumatoid Arthritis (RA) is an autoimmune disease that can cause systemic manifestations such as interstitial lung disease (ILD). In these patients serum autoantibodies may appear, such as Rheumatoid Factor (RF) and Anti-Citrullinated Peptide antibody (anti-CCP), important for its relationship with structural damage and extra-articular manifestations.
Objectives To determine the presence of anti-CCP and RF, clinical-radiological characteristics and evaluate the degree of association between the titles of anti-CCP and RF and the time course of disease in patients with RA and diagnosis of ILD.
Methods We performed a descriptive study, including 45 patients, treated at a specialized consultation Interstitial lung diseases, during the first half of 2015. Patients were subdivided into groups based on RF level: <24 U/ml Negative, 24–72 U/ml Low Titer and >72 U/ml High Titer. Anti-CCP level: 0–10 U/ml Negative, 10–150 U/ml Low Titer, 151–299 U/ml Moderate Titer and>300 U/ml High Titer.
Furthermore, ILD has been divided into different subtypes (the diagnostic includes a clinical exam, pulmonary function tests and high resolution CT): Usual Interstitial Pneumonia (UIP), nonspecific Interstitial Pneumonia (NSIP), Lymphocytic Interstitial Pneumonia (LIN), bronchiolitis obliterans (BO).
Evolution time (ET) of the disease was defined as the difference in months between the date of diagnosis of RA and the date of diagnosis of pulmonary involvement. The association between ET and Anti-CCP level and RF level was studied by two analyzes of variance of a ranking factor.
The association between the categories of titer and subtype ILD was studied by two tests Chi-square.
Results Baseline characteristics were: 32 women and 13 men with a mean age of 66±9.6 years (mean ± SD), 36 RA and 9 with secondary Sjogren's syndrome. The most common extraarticular manifestation was ocular 37%. Erosive disease was present in 80% patients.
82% were RF positive (High Titer 78% and Low Titer 22%) and 8% seronegative.
Anti-CCP were tested in 32 (71%) and present in 29 (27% High Titer, 42% Moderate Titer and 31% Low Titer).
The mean time from RA diagnosis to ILD diagnosis was 6.87 years, with a standard deviation of 6.90 years.
The time course of the disease is not significantly (p<0.05) affected by the titer of anti-CCP or the RF. On the one hand, the enormous variability in the time course of the disease and on the other the lack of information about the time of the determination of autoantibody titers, could explain the lack of statistical association found.
Among the different subtypes nor have we found: NSIP 42%, 35% UIP, LIN 7%, 15% BO. No significant association (p<0.05) between the titer of RF and anti-CCP with radiological clinical pattern in our series did not appreciate.
Conclusions In our study, the high titers of RF and anti-CCP were not associated with prematurity on lung involvement in patients with RA, considering the enormous variability in the time evolution has been observed in the sample. Moreover RF levels and anti-CCP also not associated with subtype ILD.
Further prospective studies are needed to fully assess the implications of a positive RF and anti-CCP in patients with RA and ILD.
Disclosure of Interest None declared