medwireNews: US researchers have identified a number of novel demographic, lifestyle, and clinical risk factors for rheumatoid arthritis-associated interstitial lung disease (RA-ILD), but they acknowledge that together the factors only have a moderate ability to predict development of the disease.
“Given the poor prognosis and limited available treatment options for RA-ILD, this finding emphasizes the critical need for future studies of clinical, biological, and genetic risk factors for RA-ILD,” write Jeffrey Sparks (Brigham and Women’s Hospital, Boston, Massachusetts) and co-authors in The Journal of Rheumatology.
Their nested case-control study included data for 84 people with RA-ILD and 233 people with RA but no ILD, matched on the basis of age, sex, RA duration, rheumatoid factor, and time from exposure assessment to RA-ILD onset.
After adjustment for potential confounders, the researchers identified obesity (≥30 kg/m2), high C-reactive protein levels (CRP; ≥10 mg/L) and poor functional status (multi-dimensional health assessment questionnaire [MDHAQ] ≥1) as novel predictors of RA-ILD, at significant odds ratios (ORs) of 2.42 (vs BMI 20–<25 kg/m2), 2.61 (vs CRP <3 mg/dL), and 3.10 (vs MDHAQ <0.2), respectively.
They also found that not having a college education was associated with a significantly lower risk for RA-ILD than having a college education or higher (OR=0.53), despite the fact that higher education has previously been associated with a lower risk for RA. Sparks and team suggest that this finding might be explained by higher levels of medical literacy and a willingness to undergo computed tomography imaging among the people with a higher education level “rather than a true biologic effect.”
Moderate and high levels of disease activity, as measured by DAS28-CRP, were associated with significant 2.13- and 4.28-fold higher risks for RA-ILD compared with remission, while current prednisone use was associated with a significant 3.58-fold increased risk relative to never having used the drug.
Overall, current smokers were a significant 3.27 times more likely to develop RA-ILD than people who had never smoked, but when the researchers analyzed the data according to pack–years smoked, they found that the risk was only significant among people who had at least 30 pack–years of smoking, versus never smoking, at an OR of 6.06.
The investigators comment that this finding underscores “the importance of smoking cessation to prevent RA-ILD, especially in patients who have not yet reached the critical 30 pack-year threshold.”
Area under the receiver operating characteristic curve (AUC) analysis showed that when taken together, the demographic, lifestyle, and RA-related risk factors included in the study “explain a modest amount of an individual’s risk for RA-ILD,” with an AUC of 0.79, Sparks et al remark.
The authors say their findings suggest that “disease control could reduce RA-ILD risk,” while prednisone “should be used with caution in patients with RA who are at risk for RA-ILD.”
They conclude that their data “may shed light on the potential pathogenesis of RA-ILD, could improve patient-specific risk assessment and prevention efforts, and highlight the need for further studies on risk factors for RA-ILD.”
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