# Early detection of RA‑ILD—A novel screening protocol with pulmonary function testing and lung ultrasound: A monocentric cohort study

## TL;DR

This study introduces a new method to detect lung disease in rheumatoid arthritis patients using lung function tests and ultrasound, which could lead to earlier treatment and better outcomes.

## Contribution

A novel radiation-free screening protocol combining pulmonary function testing and lung ultrasound for early detection of RA-associated ILD.

## Key findings

- 30% of patients showed reduced lung capacity and diffusion issues in pulmonary function tests.
- Lung ultrasound detected suspicious ILD patterns in 29% of patients.
- The combined method achieved 93% sensitivity and 72% specificity for ILD screening.

## Abstract

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).

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.

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.

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%.

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.

The online version of this article (10.1007/s00393-025-01775-0) includes appendices A–E.