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Prevalence of interstitial lung disease in RA increased from 2003 to 2014
The prevalence of interstitial lung disease related to rheumatoid arthritis appeared to slowly increase between 2003 and 2014, and while patient out-of-pocket costs associated with the disease remained stable over time, they were nonetheless substantial, according to data published in the Journal of Rheumatology.
“Differing case definitions and methods of case ascertainment have induced variability in estimates of the incidence and prevalence of RA-ILD,” Aryeh Fischer, MD, of the University of Colorado School of Medicine, and colleagues wrote. “It is clear that large proportions of patients with RA (30–76%) have signs of ILD on imaging studies, but ILD is deemed clinically significant in a minority (around 5–10%) of them. Certain epidemiological studies suggest the incidence of RA-ILD has been relatively stable over time, but prevalence has increased. Most studies to date have focused on older data from small subsets of the population.”
To determine the prevalence, incidence, health care costs and mortality of RA-related interstitial lung disease in the United States, Raimundo and colleagues conducted a retrospective cohort analysis of the Truven Health MarketScan Commercial and Medicare Supplemental health insurance databases from 2003 to 2014, and the Social Security Administration death database.
The researchers selected patients with RA-related interstitial lung disease based on medical claim diagnoses. Outcomes included 1-year prevalence and incidence of RA-related interstitial lung disease among the general enrollee population, all-cause and respiratory-related health care costs — in 2014 U.S. dollars — and all-cause survival for a subset of patients newly diagnosed using vital status information.
According to the researchers, the total number of patients who met the inclusion criteria ranged from 892 to 3,232 per year. The prevalence of RA-related interstitial lung disease ranged from 3.2 to six cases per 100,000 people during the 10-year study period. Disease incidence ranged from 2.7 to 3.8 cases per 100,000 people. Of the 750 incident patients with 5 years of follow-up data, 72% had an inpatient admission and 76% had an ED visit. The mean total 5-year cost was $173,405 per patient (SD = $158,837). Annual per-patient costs were highest in years 1 and 5 of the study. In addition, 35.9% of patients died by 5 years after first diagnosis in the data.
“We found the prevalence of RA-ILD has increased over the 10-year period from 2004 to 2013, while its incidence has remained fairly stable,” Fischer and colleagues wrote. “RA-ILD leads to high healthcare use and costs, due in large part to inpatient admissions, outpatient services other than office visits, and outpatient pharmacy claims. RA-ILD shortens survival, even in a presumably healthier population than those evaluated at tertiary referral centers: Within 5 years of index date, about one-third of RA-ILD patients with a potential linkage to SSDI died.” – by Jason Laday
Disclosure: The researchers report study funding from Genentech and F. Hoffman-La Roche. Please see the study for all other authors’ relevant financial disclosures.