Early detection of RA‑ILD—A novel screening protocol with pulmonary function testing and lung ultrasound

Background Seropositive rheumatoid arthritis (RA) is linked to cardiovascular and pulmonary morbidity. Nevertheless, there is currently no standardized screening method for early detection of RA-associated interstitial lung disease (ILD). Purpose This study proposes using pulmonary function testing (PFT) combined with lung ultrasound (LUS) as additional and radiation-free method to screen for ILD inRF- and ACPA-positive RA patients. Particularly in light of the increased therapeutic options, early detection of RA-ILD is associated with better outcome. Methods We included 214 consecutive patients with diagnosed RF- and ACPA-positive RA in our prospective study. These patients underwent PFT including spirometry, body plethysmography, and cardiopulmonary exercise testing as well as ultrasound examination of the lungs and the heart. Results A total of 203 patients (mean age 59 ± 12 years, 24% male, 43% current or previous smokers) were examined. The overall average RA duration was 8 ± 7 years, with 32% of all patients suffering from an erosive disease course. In PFT, 60 patients (30%) showed a limitation in forced vital capacity (FVC) as well as a diffusion disorder, defined as FVC and diffusing capacity of the lung for carbon monoxide (DLCOc) ≤ 80%. Ultrasound changes were seen in 107 patients (53%), with 29% ( n = 58) showing typical LUS patterns suspicious of ILD. In summary, ILD was suspected in almost 16% of patients ( n = 32). With the combination of PFT and LUS, our ILD screening protocol achieves a high level of sensitivity (93%) and specificity of 72%. Conclusion Our study contributes to the growing body of evidence supporting the use of LUS for screening for RA-associated ILD. We propose that LUS, in conjunction with PFT, serves as a suitable imaging tool for ILD screening in RA.