Background/Purpose:

Rheumatoid arthritis (RA) and asthma are both chronic inflammatory disorders. Lung pathology is a well-known extra-articular manifestation of RA and previous studies have shown an increased risk of asthma in patients with RA. Few studies have addressed the effects of RA on asthma exacerbations. We sought to explore the association of different asthma subtypes and asthma exacerbations in hospitalized adult patients with RA.

Methods:

We conducted a cross-sectional study using data from National Inpatient Sample (NIS) for the year of 2014. Diagnosis for asthma, subtypes of asthma (i.e. allergic asthma, non-allergic asthma, exercise-induced bronchospasm and cough variant asthma) and rheumatoid arthritis were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. STATA software package was used for statistical analyses. Multivariate logistic regression models were created to adjust for potential confounders such as age, gender, race, insurance type, current tobacco abuse and obesity. Patients younger than 18 years old were excluded from the study. For asthma exacerbations, we also studied exacerbations related to acute respiratory infections (ARI) and status asthmaticus.

Results:

A total of 102,805 hospitalizations with a diagnosis of RA and 2,331,616 hospitalizations with a diagnosis of asthma were included in our study. Compared those without RA, asthma patients with RA are more likely to be older (mean age 63.1 vs 55.0), more female (85.8% vs 69.6%), more Caucasian and less African American (68.4% and 17.8% vs 62.8% and 21.6%). The adjusted OR for all types of asthma and RA was 1.52 (95% CI 1.49 – 1.56, p < 0.001). For asthma subtypes, the adjusted OR was statistically significant only for allergic asthma (OR 1.43, 95% CI 1.23 – 1.66, p < 0.001). There was no difference for non-allergic asthma (OR 1.42, 95% CI 0.84 – 2.42, p=0.190), exercise-induced bronchospasm (OR 0.91, 95% CI 0.51 – 1.60, p = 0.732), and cough-variant asthma (OR 0.89, 95% CI 0.43 – 1.86, p=0.766) in hospitalized patients with RA. For asthma exacerbations, RA was associated with a higher risk of overall exacerbations (OR 1.26, 95% CI 1.21 – 1.33 p < 0.001), including both ARI-related exacerbations (OR 1.36, 95% CI 1.17 – 1.57, p < 0.001) and non-ARI related exacerbations (OR 1.21 95% CI 1.11 – 1.31, p < 0.001). There was no difference for status asthmaticus (OR 1.17, 95% CI 0.92 – 1.48, p=0.191) in patients with RA.

Conclusion:

Our study is consistent with previous studies that RA is associated with a higher risk of asthma in hospitalized adult population. However, our subgroup analysis showed that RA is only associated with allergic subtype of asthma, which may imply complex cross-link between Th1 and Th2 type autoimmunity. Furthermore, RA is associated with higher risk of both ARI and non-ARI related asthma exacerbations, despite that RA patients are more likely to take oral steroid, which is also a Global Initiative for Asthma (GINA) guideline recommended Step 5 asthma control medication. It suggests that increased infection risk secondary to immunosuppressive medications and systemic inflammation due to RA may both play a role in the pathophysiology of asthma exacerbation.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/in-hospital-risk-of-asthma-in-patients-with-rheumatoid-arthritis-a-cross-sectional-nationwide-analysis/