Rheumatoid Arthritis–Interstitial Lung Disease in the United States: Prevalence, Incidence, and Healthcare Costs and Mortality

Objective. Interstitial lung disease (ILD) is commonly associated with rheumatoid arthritis (RA) and can have significant morbidity and mortality. The objective of this study was to calculate the prevalence, incidence, healthcare costs, and mortality of RA-related ILD (RA-ILD) in the United States. Methods. This retrospective cohort analysis used the Truven Health MarketScan Commercial and Medicare Supplemental health insurance databases from 2003 to 2014 and the Social Security Administration death database. Patients with RA-ILD were selected based on diagnoses on medical claims. Outcomes were 1-year prevalence and incidence of RA-ILD among the general enrollee population, all-cause and respiratory-related healthcare costs (2014 US$), and all-cause survival for a subset of newly diagnosed patients with vital status information. This analysis was descriptive. No statistical testing was conducted. Results. Prevalence of RA-ILD ranged from 3.2 to 6.0 cases per 100,000 people across the 10-year period and incidence ranged from 2.7 to 3.8 cases per 100,000 people. There were 750 incident patients with 5 years of followup data. Over that time, 72% had an inpatient admission and 76% had an emergency room visit. Mean total 5-year costs were US$173,405 per patient (SD $158,837). Annual per-patient costs were highest in years 1 and 5. At 5 years after first diagnosis in the data, 35.9% of patients had died. Conclusion. Prevalence of RA-ILD increased over time. For patients who could be followed over a 5-year period, healthcare use and costs were somewhat stable over time, but were substantial. RA-ILD is associated with decreased survival.