Interstitial lung disease in rheumatoid arthritis: incidence, prevalence and related drug prescriptions between 2007 and 2020

To investigate prevalence, incidence and medication of interstitial lung disease (ILD) among German individuals with rheumatoid arthritis (RA).

Nationwide BARMER claims data from 2007 to 2020 were used. RA-ILD was identified by diagnosis codes, prescription of disease-modifying antirheumatic drugs (DMARDs) and lung diagnostics. ILD was assigned as incident or prevalent relative to the year of the first diagnosis. We identified prescriptions of glucocorticoids, conventional synthetic (cs), biological (b) and targeted synthetic (ts)DMARDs, antifibrotics and rheumatology and/or pulmonology care.

Among all persons with RA (40 686 in 2007 to 85 175 in 2020), 1.7%-2.2%/year had ILD with a slight decline since 2013. Incident ILD was 0.13%-0.21% per year and remained stable over time. ILD was more common in seropositive RA, in men and in the elderly (mean age 72 years in 2020). Glucocorticoids (84% to 68%), csDMARD (83% to 55%) and non-steroidal anti-inflammatory drug use (62% to 38%) declined, while bDMARDs (16% to 24%) rose. In 2020, 7% received tsDMARDs, 3% antifibrotics, 44% analgesics and 30% opioids. DMARD therapy was more common if a rheumatologist was involved and antifibrotics if a pulmonologist was involved. Opioid use was highest if no specialist was involved (39%) but also common in rheumatology care (32%) and less frequent in pulmonology care (21%).

RA-ILD is rare and mainly affects elderly persons. No trend in incidence was observed but treatment strategies have enlarged. Specialist care is necessary to provide disease-specific therapies. The continuing high analgesic and opioid demand shows unmet needs in these patients.