A biomarker score derived from blood proteins predicted which rheumatoid arthritis (RA) patients would develop interstitial lung disease (ILD), with nearly 20% of high-risk patients in the highest quartile developing ILD within 15 years compared with fewer than 10% of low-risk patients.

The study of 2,507 patients in the VA Rheumatoid Arthritis registry found those in the highest biomarker score quartile had more than twice the risk of developing ILD during follow-up compared with those in the lowest quartile. Over 20,000 patient-years of follow-up, 153 patients developed ILD while 106 had baseline ILD. 

Researchers measured blood concentrations of eight proteins previously linked to idiopathic pulmonary fibrosis and combined them into a composite biomarker score. 

“Identification of peripheral biomarkers associated with RA-ILD may not only help to inform risk stratification and screening, but also further our understanding of the processes leading to the development and/or progression of ILD,” wrote Brent A. Luedders, MD, of the University of Nebraska Medical Center, and colleagues.

Adding the biomarker score to age, sex, smoking history, and disease activity modestly improved prediction of future ILD. Improvement was strongest when the score was categorized into quartiles.

The biomarker score's predictive value was limited by low ILD prevalence in the cohort and did not improve identification of existing ILD beyond clinical predictors. Results depended partly on matrix metalloproteinase-7, as removing it weakened findings for existing ILD. Generalizability is uncertain given the predominantly male veteran population.

The findings suggest blood biomarkers could help identify RA patients at highest risk for developing lung complications, potentially enabling earlier monitoring and intervention.

Full disclosures can be found in the study.

Source: Arthritis and Rheumatology