Background/Purpose: Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is heterogeneous with about half of patients having progressive disease. However, the rates of progression and the association of pulmonary function test (PFT) changes with subsequent lung transplant and ILD-related mortality are unclear. We determined the prevalence and outcomes for forced vital capacity percent predicted (FVCpp) decline among patients with RA-ILD.

Methods: We identified patients with RA-ILD in a large, multihospital healthcare system in the USA. All patients met 2010 ACR/EULAR classification criteria for RA and had clinically apparent RA-ILD. RA-ILD diagnosis was determined by review of high-resolution computed tomography (HRCT) imaging by up to 3 thoracic radiologists. We collected FVCpp measurements, covariates, and outcomes (lung transplant and ILD-related death) from the medical record. We used a relative FVCpp decline cutoff of >10% within 24 months. We also used a group-based trajectory model to obtain patterns of FVCpp change from RA-ILD diagnosis. The change from initial FVCpp was fitted and grouped using a maximum likelihood method. We then assessed for associations of each FVC decline definition with risk of subsequent lung transplant or ILD-related death using multivariable logistic regression, adjusted for age, sex, HRCT ILD pattern, and baseline FVCpp.

Results: We analyzed 172 patients with RA-ILD (mean age 62.2 years, 36% male) with a median of 6 FVCpp measurements per patient over 6.5 years of follow-up (Table 1). There were 7 (4%) lung transplants and 44 (26%) ILD-related deaths. 98 (57%) patients had relative decline of FVCpp by >10% over 24 months. These patients had an OR for lung transplant/ILD-related death of 2.82 (95%CI 1.31 to 6.08) compared to those that did not have >10% decline (Table 2). We identified 3 trajectory groups of FVCpp change: rapidly declining (n=24/168 [14%]), slowly declining (n=90/168 [54%]), and stable/improving (n=54/168 [32%]), Figure 1. Compared to the stable/improving group, the rapidly declining and slowly declining groups had ORs for lung transplant/ILD-related death of 19.2 (95%CI 4.9 to 75.5) and 4.85 (95%CI 1.71 to 13.8), respectively, Table 2.

Conclusion: Over half of RA-ILD patients had FVCpp decline defined by relative FVCpp decline >10% or the novel data-driven trajectory groups. The trajectory group approach identified three groups with different FVCpp trajectories, and the two declining groups had stronger associations with lung transplant or ILD-related death than the FVCpp >10% decline definition. The different trajectory groups demonstrate the heterogeneity within RA-ILD progression and the importance of PFT monitoring for identifying RA-ILD patients at the highest risk of poor outcomes.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/forced-vital-capacity-trajectories-and-risk-of-lung-transplant-and-ild-related-mortality-among-patients-with-rheumatoid-arthritis-associated-interstitial-lung-disease/