Increased Prevalence of RA-Related Interstitial Lung Disease Noted in the United States

The prevalence of rheumatoid arthritis-related interstitial lung disease has increased over the 10-year period from 2004 to 2013.

In the United States, the prevalence of rheumatoid arthritis-related interstitial lung disease (RA-ILD) has increased over 10 years from 2004 to 2013, whereas the incidence of RA-ILD has remained stable, according to study data published in The Journal of Rheumatology.

In individuals with RA-ILD, healthcare use and costs are high, due largely to inpatient admissions, outpatient pharmacy claims, and outpatient services other than office visits. A retrospective cohort analysis was conducted using data from the Truven Health MarketScan Commercial and Medicare Supplemental health insurance databases from 2003 to 2014, along with the Social Security Administration death database. The investigators sought to calculate the prevalence, incidence, healthcare costs, and mortality rates of RA-ILD in the United States.

Patients with RA-ILD were chosen based on diagnoses on medical claims. Study outcomes included 1-year prevalence and incidence of RA-ILD in the general enrollee population, respiratory-related and all-cause healthcare costs (in US dollars from 2014), and all-cause survival in a subset of patients with newly diagnosed disease and vital status information.

The prevalence of RA-ILD ranged from 3.2 to 6.0 cases per 100,000 individuals across the 10-year study period and the incidence of RA-ILD ranged from 2.7 to 3.8 cases per 100,000 individuals. Overall, a total of 750 patients with RA-ILD had 5 years of follow-up data available. In that time period, 72% of patients with the disease experienced an inpatient hospital admission and 76% had an emergency department visit.

The average total 5-year costs were $173,405±$158,837 per patient. The median all-cause 5-year costs were US $132,929. Moreover, the average total respiratory-related 5-year costs were $24,133±$42,942.

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The mean annual per-patient cost was highest in years 1 and 5, which was also true for all-cause cost. As with the 12-month costs, the main cost drivers of mean costs in the 5-year follow-up analysis included inpatient admission, outpatient pharmacy claims, and the use of other outpatient services.

In patients who could be followed over a 5-year period, although healthcare use and costs remained fairly stable over time, they were substantial. Furthermore, the researchers also noted that the presence of RA-ILD was shown to shorten patient survival.

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Raimundo K, Solomon JJ, Olson AL, et al. Rheumatoid arthritis-interstitial lung disease in the United States: prevalence, incidence, and healthcare costs and mortality [published online November 15, 2018]. J Rheumatol. doi:10.3899/jrheum.171315