Proposal of a radiation-free screening protocol for early detection of interstitial lung involvement in seropositive and ACPA-positive rheumatoid arthritis.

Background: Seropositive rheumatoid arthritis (RA) is associated with significant cardiovascular and pulmonary morbidity. However, screening for early detection of pulmonary involvement especially interstitial lung disease (ILD) is not established in RA.

Methods: We propose a non-invasive radiation-free approach to screen for interstitial lung involvement (ILI) by means of pulmonary function tests (PFT) and pleuro-pulmonary transthoracic ultrasound (LUS) with additional cardiopulmonary exercise tests (CPET) with ECG, and echocardiography. We included patients with confirmed diagnosis of seropositive RA according to ACR criteria, but without symptoms for or known cardiopulmonary disease. ILD was suspected when significant LUS abnormalities and additional PFT changes were present.

Results: We included 67 consecutive patients (78% female, mean age 61 ± 12 years, 48% active or previous smokers), who fulfilled the inclusion criteria and gave written informed consent. We found 48% of patients with suspected changes in PFT with a diffusion capacity (DLCOc-SB) ≤ 80%, among them 7% with forced vital capacity (FVC) ≤ 80%. In 40% of patients, we found noticeable changes in LUS, 24% with an ILD compatible pattern. In 16% of cases, LUS abnormalities and additional PFT changes were present, and ILI was suspected. Additional findings included obstructive lung disease (n = 11), subpleural consolidation (n = 6) including one confirmed lung cancer, minimal pleural effusion (n = 6), and ischemic cardiac disease (n = 2). None of the patients showed signs of pulmonary vascular involvement.

Conclusions: ILI was suspected in 16% of cases using a new radiation-free screening protocol in asymptomatic RA patients.

Trial registration: German Register of Clinical Studies (DRKS00028871).