Pulmonary involvement in newly diagnosed and untreated rheumatoid arthritis and psoriatic arthritis: a prospective longitudinal study.

Objectives: To longitudinally assesses pulmonary involvement in newly diagnosed rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients over a 12-months follow-up. To identify biomarkers and establish a diagnostic algorithm for monitoring pulmonary changes.

Methods: Newly diagnosed RA and PsA patients were examined with clinical and laboratory assessments, pulmonary function tests (PFT), and chest radiography (CXR) at three-months intervals for one year.

Results: The study enrolled 50 patients (26 RA, 24 PsA) and 26 controls. At baseline, 37.0% of arthritis patients (50.0% RA, 22.7% PsA) exhibited radiographic pulmonary involvement, with 64.7% being asymptomatic. No association was observed between CXR and PFTs. Reduced pathological breathing width was noted in 64.0% of patients (RA 69.2%, PsA 58.3%) and 23.1% of controls (p < .001). Thoracic excursion and lung auscultation showed no differences. During follow-up, PFT and physical examination findings remained stable. Mean CRP levels significantly decreased in RA patients from 23.5 mg/l (± 33.6; 95% CI: 9.9-37.1) to 2.7 mg/L (± 3.4; 95% CI: 1.0-4.3), and in PsA patients from 13.3 mg/L (± 18.0; 95% CI: 5.7-20.9) to 8.1 mg/L (± 16.2; 95% CI: 0.1-16.2) (p < .001). Additionally, significant reductions in disease activity scores and improvements in six-minute walking distance were observed (p < .001). No associations were identified between PFT outcomes, disease activity, or rheumatological medications throughout the disease course.

Conclusion: Our study underscores the prevalence of significant, predominantly asymptomatic pulmonary involvement in newly diagnosed RA and PsA patients. The lack of correlation between pulmonary function, disease activity, and medication during disease progression suggests that reducing arthritic disease activity does not necessarily mitigate the risk or severity of pulmonary involvement. Finally, our finding underscore the need for more sensitive biomarkers and optimized monitoring strategies.