To analyze the clinical characteristics of interstitial pulmonary fibrosis (IPF) in patients with Rheumatoid arthritis (RA).
We retrospectively analyzed 198 RA patients with or without IPF. Characteristics of RA-IPF in clinical and lab data were analyzed. Age, duration of disease, clinical and laboratory parameters, history of smoking and medicine were compared between the patients with and without IPF.
(1) Among the 198 RA patients, 15.2% (30/198) were found with IPF. 100% RA-IPF patients had HRCT findings. However, 63.3% (19/30) had positive findings in chest X-ray, and only 46.7% (14/30) had the complaints of cough and short breath. Velcro rales were found in 50.0% (15/30) patients with IPF and no acropachy occurred. Only one patient suffered from hypoxemia. IPF presented after the joint symptoms in most patients. (2) RA-IPF patients were older than those without IPF [(65.50 +/- 9.71) vs (55.22 +/- 12.98) years, P<0.01]; Higher positivity of anti-keratin antibodies (AKA) were found in RA-IPF compared to patients without IPF (61.5% vs 35.9%, P=0.014). Furthermore, the levels of anti-cyclic citrullinated peptide (CCP) antibody were significantly higher in RA-IPF [(4.38 +/- 2.08) vs (3.20 +/- 2.12), P=0.01]. No differentiation of duration of disease, history of smoking and medicine, IgM rheumatoid factor, IgG rheumatoid factor, anti-nuclear antibody, anti-SSA antibody and levels of immunoglobins and complements were found between the two groups of RA patients with and without IPF.
The clinical symptoms of IPF in RA patients are mild and more common in older patients. AKA and anti-CCP antibody might be important antibodies associated with RA-IPF.