According to a study published in Arthritis Research & Therapy, in patients with RA, factors such as age at disease onset, higher BMI, oral glucocorticoid use, and smoking history are correlated with the incidence of ILD.

The researchers sought to examine the clinical characteristics of patients with RA-ILD versus those with RA without ILD (RA-non-ILD).

The study was a single-center cohort of patients with RA-ILD that employed a multidisciplinary collaborative approach. The researchers sought to compare the long-term prognosis between RA-ILD patients and RA-non-ILD patients and to explore prognostic factors among RA-ILD patients. The researchers measured functional disability and quality of life by using a self-reported questionnaire and measured lung function.

The researchers used multivariable logistic regression to identify factors correlated with ILD in patients with RA, including the age of disease onset, BMI, smoking history, oral glucocorticoid use, and methotrexate use.

After enrollment, the demographics, such as current age, age at onset of RA diagnosis, gender, BMI, smoking, income, education level, and clinical information, were collected, and rheumatologists evaluated the RA disease activity.

Among 148 patients with RA-ILD, 35.8% were males, and the average age was 65.8 years ± 9.9. Among those classified as RA-non-ILD patients, there were 410 patients with an average age of 58.0 years ± 10.4 and 14.6% were males.

The results revealed that the RA-ILD versus the RA non-ILD group had a higher percentage of late-onset RA patients (aged ≥60 years) than in the comparator group (43.9% vs. 14.2%, P <.001). Multivariable logistic regression analysis disclosed that higher age at RA onset (odds ratio [OR] 1.056; 95% CI, 1.021-1.091); higher BMI (OR 1.65; 95% CI, 1.036-2.629); smoking history (OR 2.484; 95% CI, 1.071-5.764); and oral glucocorticoid use (OR 3.562; 95% CI, 2.160-5.874) were linked with ILD in RA patients, whereas the use of methotrexate was less likely to be linked with ILD (OR 0.253; 95% CI, 0.155-0.412).

The authors noted that their findings demonstrated distinct clinical characteristics of RA-ILD patients compared with RA-non-ILD patients.

Based on the findings, the authors wrote, “In the cross-sectional study which used the enrollment data of this prospective cohort, we demonstrated that higher age at RA diagnosis, a higher BMI, and smoking were associated with accompanying ILD in RA patients. In addition, we found that RA-ILD patients tended to use glucocorticoids more frequently and less frequently used methotrexate as compared with RA-non-ILD patients.”

Additionally, the authors indicated that limitations of the study included its cross-sectional design, which did not enable them to examine the causal relationships between clinical factors and ILD in RA patients.

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