Validation study of the SER/SEPAR screening criteria for interstitial lung disease in early rheumatoid arthritis patients

Objective

In 2023, the Spanish Society of Rheumatology (SER) and the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) proposed screening criteria for interstitial lung disease (ILD) in rheumatoid arthritis (RA) based on expert opinion, requiring validation. This study aimed to evaluate their sensitivity and specificity in a cohort of early RA patients.

Methods

This cross-sectional study retrospectively assessed the SER/SEPAR criteria in 146 early RA patients screened for ILD at diagnosis. Screening included medical history, respiratory auscultation, chest X-ray (CXR), and complete pulmonary function tests (PFTs). Thoracic high-resolution computed tomography (HRCT) was performed only in the presence of symptoms, velcro crackles, or abnormalities on CXR or PFTs.

Results

Among the 146 patients included, 28 (19.2 %) developed ILD, all confirmed by HRCT. Of these, 12 (43 %) had clinically evident ILD preceding or coinciding with joint symptoms, while the remaining 16 (57 %) were identified after applying the screening protocol. At diagnosis, 90 patients (61.6 %) met the screening criteria, with ILD confirmed in 26 cases (28.9 %). Conversely, among 56 patients (38.4 %) not meeting the criteria, ILD was ultimately identified in 2 cases (3.5 %). The SER/SEPAR screening criteria demonstrated a sensitivity of 92.9 % (95 % CI: 76.5–99.1), specificity of 45.8 % (95 % CI: 36.6–55.2), LR+ of 1.71 (95 % CI: 1.41–2.08), LR– of 0.16 (95 % CI: 0.04–0.60), PPV of 28.9 % (95 % CI: 25.1–33.1), NPV of 96.4 % (95 % CI: 87.5–99.1), and diagnostic accuracy of 54.8 % (95 % CI: 46.4–63.1).

Conclusion

The SER/SEPAR criteria for ILD screening demonstrated high sensitivity in recent-onset RA patients, supporting their utility as a tool for early detection in this scenario.