Background/Purpose:

Interstitial lung disease (ILD) is recognized as a frequent extra-articular manifestation of rheumatoid arthritis (RA) associated with significant morbidity and mortality. Nevertheless, risk factors predicting progression of pulmonary disease in RA-ILD are poorly understood. Specifically, no studies to date have examined whether race/ethnicity or cyclic citrullinated peptide (CCP) antibodies are associated with a progressive disease course. In addition, the frequency of parallel lung and joint activity in patients with RA-ILD is unknown. We assessed the aforementioned clinical factors, along with others, for their association with progressive RA-ILD. We secondarily examined how often pulmonary activity parallels RA joint activity.

Methods:

We performed a retrospective observational study of 47 adults with RA-ILD who met ACR 1987 classification criteria for RA and had typical interstitial abnormalities on chest CT not due to other causes. Progressive RA-ILD was defined as a decrease in forced vital capacity of >10% predicted or diffusing capacity for carbon monoxide of >15% predicted on a minimum of two successive pulmonary function tests (PFTs) ≥8 weeks apart. Parallel ILD and joint activity required concordant worsening in PFTs and evidence of joint disease flare over a three month period. Fisher’s exact test and logistic regression were used to compare categorical variables of interest, while an unpaired t-test and logistic regression were used for continuous variables.

Results:

Thirty six patients (77%) had progressive RA-ILD; 11 patients (23%) had stable RA-ILD. On bivariate analysis, high-titer rheumatoid factor (RF) was significantly associated with progressive RA-ILD (p=0.0394). There was also a trend toward association in African Americans (p=0.0912), as well as in patients with high-titer CCP antibodies (p=0.0973) and history of tobacco abuse (p=0.0933). Multivariate analysis using regular logistic regression with overall model fit of p <0.05 suggested statistically significant association with high-titer RF (p=0.0378), and a trend toward association with ILD progression in African Americans (p=0.0514) and in those with a smoking history (p=0.0820). Exact logistic regression, however, revealed only a trend toward association between presence of high-titer RF and progressive RA-ILD (p=0.0936). Twenty eight patients had serial rheumatology assessments coinciding with PFTs: 9 patients (32%) had parallel ILD and joint activity. None of the factors associated with RA-ILD disease progression were significantly associated with parallel or non-parallel ILD and joint activity.

Conclusion:

RA-ILD patients with high-titer RF in particular, as well as those who are African American or have a history of tobacco abuse may be at higher risk for progressive lung disease and warrant close monitoring. In contrast, multivariate analysis suggests that high-titer CCP antibodies do not appear to be associated with disease progression. As most RA-ILD patients did not have parallel ILD and joint activity, different factors may contribute to pulmonary and articular disease flares.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/identifying-risk-factors-for-progression-of-rheumatoid-arthritis-associated-interstitial-lung-disease/