Breathing New Life into Interstitial Lung Disease in Rheumatoid Arthritis

Validation of an algorithm to identify incident interstitial lung disease in patients with rheumatoid arthritis

Background/purpose

Interstitial lung disease (ILD) is an important problem for patients with rheumatoid arthritis (RA). However, current approaches to ILD case finding in real-world data have been evaluated only in limited settings and identify only prevalent ILD and not new-onset disease. Our objective was to develop, refine, and validate a claims-based algorithm to identify both prevalent and incident ILD in RA patients compared to the gold standard of medical record review.

Methods

We used administrative claims data 2006–2015 from Medicare to derive a cohort of RA patients. We then identified suspected ILD using variations of ILD algorithms to classify both prevalent and incident ILD based on features of the data that included hospitalization vs. outpatient setting, physician specialty, pulmonary-related diagnosis codes, and exclusions for potentially mimicking pulmonary conditions. Positive predictive values (PPV) of several ILD algorithm variants for both prevalent and incident ILD were evaluated.

Results

We identified 234 linkable RA patients with sufficient data to evaluate for ILD. Overall, 108 (46.2%) of suspected cases were confirmed as ILD. Most cases (64%) were diagnosed in the outpatient setting. The best performing algorithm for prevalent ILD had a PPV of 77% (95% CI 67–84%) and for incident ILD was 96% (95% CI 85–100%).

Conclusion

Case finding in administrative data for both prevalent and incident interstitial lung disease in RA patients is feasible and has reasonable accuracy to support population-based research and real-world evidence generation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02655-z.

The Association Between MUC5B Mutations and Clinical Outcome in Patients with Rheumatoid Arthritis-Associated Interstitial Lung Disease: A Retrospective Exploratory Study in China

Background

Patients with rheumatoid arthritis (RA) who develop interstitial lung disease (RA-ILD), show features of usual interstitial pneumonia (UIP) on high-resolution computed tomography (HRCT). This retrospective exploratory clinical study aimed to investigate the association between mutations in the MUC5B gene and clinical outcome in patients with RA, with or without RA-ILD, using whole-exome sequencing (WES).

Material/Methods

WES was performed using peripheral blood samples for mutations in the MUC5B gene in 51 patients diagnosed with RA without ILD, and 45 patients with RA-ILD. The cumulative incidence in acute exacerbations of RA-ILD and variables associated with acute exacerbations of RA-ILD were analyzed.

Results

In patients with RA-ILD, the main genetic variants of MUC5B were identified, with an odds ratio (OR) of 3.410 (p=0.013). Nine patients with RA without ILD (17.6%) and 19 patients with RA-ILD (42.2%) expressed MUC5B variants. Patients with RA-ILD carrying MUC5B variants had a significantly increased duration of RA-ILD (p=0.03) and showed a UIP pattern on lung HRCT (p=0.01). Acute exacerbations of RA-ILD occurred in 25 patients during follow-up, including 13 patients with mutant MUC5B and 12 patients with wildtype MUC5B. Univariate analysis showed that MUC5B mutations (p=0.043), older age of onset of RA (p=0.041), increased serum anti-citrullinated protein antibodies (ACPAs) (p=0.033), and a UIP imaging pattern on HRCT (p=0.015) were significantly correlated with acute exacerbations of RA-ILD. However, these findings were not supported by multivariate analysis (p=0.065).

Conclusions

The carrier status of MUC5B variants was an indicator of reduced prognosis and increased exacerbations of RA-ILD.