Rheumatoid arthritis development and survival in idiopathic interstitial pneumonia patients with anti-citrullinated...

Some patients with idiopathic interstitial pneumonia (IIP) with anti-citrullinated protein antibodies (ACPA) develop rheumatoid arthritis (RA) during the early phase of ACPA positivity, whereas others develop RA either in the late phase or not at all; however, the clinical factors that predict RA development and survival outcome in these patients remain unknown.

Retrospective clinical data from IIP patients without an RA diagnosis at the time of ACPA positivity were analysed. The chest high-resolution computed tomography (HRCT) score was calculated based on the extent of the lesions.

Of 78 patients enrolled, 46 (59.0 %) were diagnosed with RA during a median observation period of 49.3 months. The cumulative incidence of RA at 48 months was significantly higher in patients with high-positive ACPA than those with low-positive ACPA (67.5 %) vs. 36.3 % low-positive ACPA, p = 0.01). Multivariate analysis identified the high-positive ACPA and the high fibrosis score as significant predictors of RA development (hazard ratio [HR], 3.28, p < 0.01; and HR 1.57, p = 0.02, respectively). Additionally, Cox regression analysis revealed the fibrosis score and glucocorticoids and/or immunosuppressive agent treatment were associated with increased all-cause mortality (HR 1.76, p = 0.02; and HR 3.32, p < 0.01, respectively).

In ACPA-positive IIP patients, high-positive ACPA and high fibrosis scores might be the risk factors for imminent RA development. Furthermore, high fibrosis score was associated with poor survival outcomes. Pulmonologists should consider to enlist the help of rheumatologists for patients with high ACPA titres and extensive fibrotic changes.