Background: Rheumatoid Arthritis is a symmetric, inflammatory polyarthritis characterized by erosion of cartilage and bone leading to joint destruction. Apart from the articular target, nonarticular tissues can also be affected leading to severe systemic disease.
Objectives: We aim to evaluate the incidence of interstitial lung disease in Rheumatoid arthritis, the association and severity in hospitalized patients.
Methods: We analyzed data of patients 18 years and above hospitalized with a primary or secondary diagnosis of Rheumatoid Arthritis admitted in United States hospitals from 2017 to 2021 using the National Inpatient Sample (NIS) data.
Results: The mean age of patients with rheumatoid arthritis was 67.8 years, and the mean length of hospital stay was 5.2 days. The rheumatoid arthritis patients were older than non-rheumatoid patients admitted to the hospitals (67.8 vs. 57.9 years, p<0.001). The rheumatoid arthritis patients were predominantly females (73.8%). Compared with other patients admitted to the hospital, the rheumatoid arthritis patients were more likely to have interstitial lung disease (3.4% vs. 0.7%, p<0.001). In the bivariate analysis of patients with rheumatoid arthritis, patients with interstitial lung disease were older than those without (71.08 vs. 67.66 years, p<0.001). Males were more likely to have interstitial lung disease compared to females (4% vs. 3.2%, p<0.001). The odds of having interstitial lung disease increased with age from 1.6% in those between 18 and 44 years to 4.3% in those 75 years and above. Compared to other racial groups, Whites were less likely to have interstitial lung disease (3.2% vs. 4.1%, p<0.001). Patients with interstitial lung disease were more likely to die during hospital admission (7.6% vs. 3.3%, p<0.001). They were also more likely to have pulmonary hypertension (11.7% vs. 2.9%, p<0.001), rheumatoid vasculitis (5.6% vs. 3.4%, p=0.007), rheumatoid polyneuropathy (5.7% vs. 3.4%, p=0.005), and rheumatoid nodule (8% vs. 3.4%, p<0.001). Furthermore, patients with interstitial lung disease were more likely to have heart failure (5.3% vs. 2.8%, p<0.001), atrial fibrillation (4.3% vs. 3.2%, p<0.001), pleural effusion (4.2% vs. 3.4%, p<0.001) and pneumothorax (9.9% vs. 3.4%, p<0.001). In the multivariate analysis of patients with Rheumatoid arthritis, interstitial lung disease was associated with increased odds of in-hospital mortality (OR 1.88, 95% CI 1.76-2.01, p<0.001), length of stay (OR 1.01, 95% CI 1.009-1.012, p<0.001), pulmonary hypertension (OR 3.66, 95% CI 3.51-3.81, p<0.001), heart failure (OR 1.34, 95% CI 1.29-1.39, p<0.001), pneumothorax (OR 2.38, 95% CI 1.99-2.84, p<0.001), rheumatoid vasculitis (OR 1.75, 95% CI 1.19-2.48, p=0.005), rheumatoid nodule (OR 2.36, 95% CI 1.64-3.39, p<0.001), and rheumatoid polyneuropathy (OR 1.73, 95% CI 1.19-2.52, p=0.004). The odds of interstitial lung disease increased with age, with the highest odds in patients 75 years and above (OR 2.42, 95% CI 2.21-2.64, p<0.001).
Conclusion: Our analysis of the largest hospital database in the USA demonstrates interstitial lung disease in hospitalized Rheumatoid Arthritis patients leads to increased complications and all cause mortality. A slightly different treatment approach targeting non-articular organ systems, early in disease onset, in Rheumatoid arthritis could show improvement in the overall disease outcome.
REFERENCES: NIL.
Acknowledgements: NIL.
Disclosure of Interests: None declared.
© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (