Heterogeneity of Rheumatoid Arthritis-Associated Interstitial Lung Disease by Longitudinal Forced Vital Capacity Trajectory and Associations With Disease Outcomes.

OBJECTIVE

We aimed to identify unique disease trajectories within rheumatoid arthritis-associated interstitial lung disease (RA-ILD) based on longitudinal forced vital capacity (FVC) values and their associated clinical outcomes.

METHODS

We performed a cohort study of RA-ILD within the Veterans Health Administration from 1999 to 2021. Patients with RA-ILD were identified with validated algorithms. Group-based trajectory modeling was used to identify unique groups based on longitudinal FVC values in a primary cohort with baseline and follow-up FVC values and an overall cohort with at least one FVC value. Associations of group assignment with survival and respiratory hospitalization were tested in multivariable Cox regression models adjusting for initial FVC.

RESULTS

We derived three FVC trajectory groups in the primary cohort (n = 1,092) and eight in the overall cohort (n = 5,172). A total of 82.5% (primary cohort) and 54% (overall cohort) of patients with RA-ILD belonged to progressive groups with FVC percent predicted change ranging from -2.16 to -10.78 (primary) and -0.73 to -1.56 (overall) per year. Relative to the stable group, slow (adjusted hazard ratio [aHR] 1.55 and 1.38) and rapid (aHR 2.07 and 1.77) progressors in the primary cohort had an increased risk of death and respiratory hospitalization, respectively. In the overall cohort, patients with a progressive FVC trajectory also experienced an increased risk of death (aHR range 1.18-2.69) and respiratory hospitalization (aHR range 1.29-2.78).

CONCLUSION

Unique disease trajectories based on longitudinal FVC values are independently associated with the risk of death and respiratory-related hospitalization in RA-ILD. Recognition of these unique RA-ILD trajectories could inform management and monitoring.