Background Rheumatoid arthritis (RA) is associated with a wide range of extra-articular manifestations. Non-cardiac thoracic manifestations occur in approximately 5–20% and can affect the pleura, pulmonary parenchyma, airways and vasculature¹. Besides, patients can also experience drug-induced pulmonary disease related to RA medication².

Objectives To characterize lung involvement and factors associated with lung disease in a cohort of RA patients.

Methods Retrospective analysis of RA patients followed in our Rheumatology department. Lung involvement was defined by the presence of imagiological/histopathological alterations described in the spectrum of rheumatoid arthritis-associated lung disease in either symptomatic or asymptomatic patients. Logistic regression analysis was used to evaluate demographic and clinical features independently associated with lung disease.

Results In total, 532 RA patients were analysed, 400 females, mean age of 63.6 (±13.8) years and mean disease duration of 11.8 (±9.5) years. Rheumatoid factor (RF) was positive in 69% and anti-cyclic citrullinated peptide antibodies (ACPA) in 60%; 8.8% were current smokers and 7.5% past smokers. Methotrexate (MTX) was the most prescribed synthetic DMARD (85.9%) and biologics were used in 32.3% of patients.

Lung involvement was documented in 38 patients (7.1%; 95% CI 5.2%>9.7%). The specific types of lung disease are presented in figure 1. The mean interval between articular and pulmonary symptoms was 6.1 (±6.4) years, with only 1 patient having lung involvement diagnosed prior to joint manifestations. Most patients were female (73.7%), 78.9% RF positive, 68.4% ACPA positive and 29% current/previous smokers. Secondary Sjögren's Syndrome was present in 5 patients. Eighteen (47%) patients were medicated with MTX, 16 of them initiated therapy before developing respiratory symptoms and 10 (26.5%) with biologics (4 with TNF antagonists, 3 with tocilizumab, 2 with rituximab and 1 with abatacept). Most patients (92.1%) had abnormal chest x-rays, but only 47.4% were symptomatic. Pulmonary function tests (PFT) were abnormal in 31.6% of patients and 47.4% had diffusing capacity for carbon monoxide (DLCO) less than 75% predicted (7 had no DLCO estimated). Respiratory insufficiency was present in 7 (18.4%) patients.

In multivariate logistic regression analysis, current MTX use (OR: 2.1 [1.02–4.33]), RF positivity (OR: 3.48 [1.18–10.25]) and older age (OR: 1.03 [1.00–1.06)] were independently associated with lung involvement.

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Conclusions Lung involvement was present in 7.3% of our cohort and was diagnosed in average 6.1 years after the first joint manifestations. RF positivity, older age and current MTX use are associated with lung disease.

As most patients remain asymptomatic, lung involvement is probably underdiagnosed in RA patients. Besides, in clinical practice exams that can detect preclinical disease, such as high-resolution chest computed tomography, are usually reserved for symptomatic patients or with an abnormal chest x-ray.

References

1. Chansakul T, Dellaripa, Doyle TJ, Madan R. Intra-thoracic rheumatoid arthritis: imaging spectrum and treatment related complications. Eur J Radiol. 2015 October; 84(10): 1981–1991.

2. Megan Shaw, Bridget F. Collins, Lawrence A. Ho and Ganesh Raghu. Rheumatoid arthritis-associated lung disease. Eur Respir Rev 2015; 24: 1–16.

References

Disclosure of Interest None declared