Change in serum marker levels tied to outcomes of RA-related interstitial lung disease

In rheumatoid arthritis-related interstitial lung disease (RA-ILD), change over time in the levels of serum proteins, such as matrix metallopeptidase 13 (MMP13) and C-X-C motif ligand chemokine 11 (CXCL11), predict clinical outcomes, a recent study has found. The same is true for baseline clinical factors such as patient age and rheumatoid factor (RF).

The study included 60 RA patients who underwent clinical examinations and pulmonary function tests at baseline and 5 years after enrolment. Serum protein levels were quantified using a multiplex enzyme-linked immunosorbent assay, while high-resolution computed tomography was performed to measure other ILD-related factors.

Nineteen patients saw radiographic progression of RA-ILD, while the remaining 41 did not. Comparing both groups revealed that the former was significantly older (mean age, 61.1 vs 45.1 years; p=0.002) and had a significantly higher RF at baseline (195.0 vs 105.0 IU/mL; p=0.044).

Moreover, correlation analysis confirmed that age was significantly and positively correlated with the risk of disease progression (beta, 0.057; p=0.015). Similar signals were reported for the 5-year change in the log of the serum levels of MMP13 and CXCL11, though significance was not reached.

Receiver operating characteristic curve analysis additionally showed that a model incorporating age, CXCL11, and MMP13 could reliably differentiate progressors from nonprogressors (area under the curve, 0.7772, 95 percent confidence interval, 0.6384–0.9161; p<0.01).

“Longitudinal assessment of additional RA-ILD patients from larger, independent cohorts will be necessary to verify our findings and fully determine the predictive value of identified biomarkers, including their ability to distinguish outcomes of RA-ILD from those of other forms of ILD and/or idiopathic pulmonary fibrosis,” the researchers said.