TOPLINE:

In patients with rheumatoid arthritis (RA), age at the onset of RA, smoking exposure, and rheumatoid factor or anti-cyclic citrullinated peptide seropositivity were independently associated with the development of interstitial lung disease (ILD). Comorbidities measured using rheumatic disease-specific comorbidity indices — the Rheumatic Disease Comorbidity Index (RDCI), but not general comorbidity indices, were associated with increased odds of ILD.

METHODOLOGY:

• Researchers conducted a retrospective analysis to examine associations between baseline comorbidities and the subsequent development of ILD in patients with RA.
• They included data of 2701 patients with RA from two UK multicentre RA inception cohorts who were followed up for 25 and 10 years in the respective studies.
• Sociodemographic, clinical, laboratory, and functional data were collected at baseline and 3-6 and 12 months and annually thereafter.
• The baseline comorbidity burden was assessed using the RDCI — evaluating the effect of comorbidities in RA; Charlson Comorbidity Index (CCI) — general comorbidity index, not specific to RA; and major comorbidity count — specifying the number of comorbidities.
• Patients with ILD were identified on the basis of prior diagnosis, diagnosis at follow-up, or diagnosis as listed in the death certificates.

TAKEAWAY:

• Overall, 3.7% of patients with RA were diagnosed with ILD. Patients with RA who developed ILD, compared with those who did not, were older at the onset of RA (median age, 62 vs 57 years).
• Older age at the onset of RA (adjusted odds ratio [aOR], 1.03; P < .01), either rheumatoid factor or anti-cyclic citrullinated peptide seropositivity (aOR, 2.58; P < .01), and ever-smoking status (aOR, 1.70; P < .05) were each associated with increased odds of developing ILD in patients with RA.
• Each unit increase in the RDCI score was associated with increased odds of ILD (aOR, 1.32; P < .05). The RDCI was also associated with increased odds of ILD after the inclusion of only the lung disease component (aOR, 4.59; P < .01).
• No significant association was found when assessing comorbidity with the CCI or major comorbidity count, regardless of the inclusion of lung disease.

IN PRACTICE:

"[The study] finding suggests that ILD stratification in the clinical practice should focus on a history of prior lung diseases. Screening for lung diseases in patients with RA in the routine clinical practice may provide additional insights," the authors wrote.

SOURCE:

This study was led by Rositsa Dacheva, an independent researcher, Sofia, Bulgaria, and Amanda Busby, Centre for Health Services and Clinical Research, University of Hertfordshire, Hertfordshire, England. It was published online on February 14, 2026, in Rheumatology.

LIMITATIONS:

The study analysed historical cohorts who were followed up in the pre-biologic era. The diagnosis of ILD may not have been based on imaging, which may have led to underdiagnosis. Data on smoking status were not collected at baseline in one cohort, which might have resulted in an underestimation of the prevalence.

DISCLOSURES:

The Early Rheumatoid Arthritis Study received grants from the Arthritis Research Campaign and the British United Provident Association Foundation and was supported by the National Institute for Health and Care Research Clinical Research Network (CLRN), Essex & Hertfordshire. The Early Rheumatoid Arthritis Network received funding from the British Society for Rheumatology and a grant from the Healthcare Commission. One author reported receiving a grant from the Essex & Hertfordshire CLRN and along with two other authors reported serving as associate editors of Rheumatology.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.