Trends in mortality among patients with Rheumatoid arthritis and interstitial lung disease in the United States, 1999-2020, a population-based retrospective study.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disorder that commonly involves the lungs, leading to interstitial lung disease (ILD). RA-associated ILD (RA-ILD) contributes substantially to morbidity and mortality. AIMS: To examine long-term national trends and demographic patterns in mortality related to RA-ILD in the United States over a 22-year period. METHODS: We performed a retrospective analysis using data from the Centers for Disease Control and Prevention Multiple Cause of Death database. Mortality records for adults aged ≥ 25 years were reviewed, identifying cases in which both RA and ILD were listed. RA was defined using ICD-10 codes M05-M06, and ILD using code J84. Age-adjusted mortality rates (AAMRs) per million populations were calculated. RESULTS: A total of 7,435 deaths met inclusion criteria, yielding a crude mortality rate of 1.7 per 1,000,000 populations. Females accounted for most deaths (n = 4,730, 63.6%). White individuals represented 88.8% (n = 6,601) of deaths, followed by Black or African American individuals (7.2%). Most deaths occurred in metropolitan areas (n = 5956, 80.1%) and within medical facilities (n = 4455, 59.97%). AAMRs initially increased from 1999 to 2002 (annual percent change [APC] + 6.34%, p < 0.05), stabilized thereafter, and declined from 2008 to 2020 (APC - 1.34%, p < 0.05). CONCLUSIONS: RA-ILD mortality has demonstrated notable temporal changes in the U.S., with substantial demographic disparities. Despite therapeutic progress, pulmonary complications remain a significant cause of death in RA, underscoring the need for early ILD detection, coordinated rheumatology-pulmonology care, and improved access to specialized services.