From the Journals

U.S. increases in RA burden outpace global averages



Three major indicators of rheumatoid arthritis burden in the United States all increased more rapidly than did global averages from 1990 to 2017, according to a new analysis of RA activity in 195 countries.

Increasing burden of RA in the United States, 1990-2017

Percentage changes in the incidence, prevalence, and disability-adjusted life-year (DALY) rates for RA all reached double digits in the United States over the study period, but global increases for those measures stayed in the single digits, except for DALY, which did not increase, Saeid Safiri, PhD, of Tabriz (Iran) University of Medical Sciences and associates wrote in Annals of the Rheumatic Diseases.

Data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 show that RA incidence in the United States had the largest increase (20.7%) among the three measures, rising from 19.3 cases per 100,000 population in 1990 to 23.4 in 2017. Overall incidence for the 195 countries included in the study went from 13.7 to 14.9 cases per 100,000, for an increase of 8.2%, the investigators reported.

That pattern largely repeats for prevalence: an increase of 17.5% in the United States as the number of cases went from 336.5 per 100,000 in 1990 to 395.5 in 2017, and an increase of 7.4% globally, with the number of prevalent cases rising from 229.6 to 246.5 per 100,000, they said.

The DALY numbers – think of each DALY as 1 lost year of “healthy” life, the World Health Organization says – tell a somewhat different story. The United States had DALY rate of 53.2 per 100,000 in 1990, but by 2017 it had climbed to 60 per 100,000, an increase of 12.8%. Over that same time period, the global rate fell by 3.6% as it went from 44.9 to 43.3, Dr. Safiri and associates reported.

That long-term decline does, however, disguise a more recent trend. The global DALY rate “decreased from 1990 to 2012 but then increased and reached higher than expected levels in the following 5 years to 2017,” they wrote.

RA rates in the United States in 2017 were, as noted, above average, but they were not the highest. The United Kingdom achieved the RA trifecta of highest incidence (27.5 per 100,000), highest prevalence (471.8 per 100,000), and highest DALY rate (73 per 100,000) among the 195 countries in the study. At the other end of the three scales, Indonesia had the lowest incidence (5.6 per 100,000) and prevalence (91.1 per 100,000), and Sri Lanka had the lowest DALY rate (14.2 per 100,000), they said.

“Age-standardized prevalence and incidence rates are overall increasing globally. Increasing population awareness regarding RA, its risk factors and the importance of early diagnosis and treatment with disease-modifying agents is warranted to reduce the future burden of this condition,” the research team concluded.

GBD is funded by the Bill and Melinda Gates Foundation. The current analysis also was supported by Social Determinants of Health Research Center, Shahid Beheshti University of Medical Sciences in Tehran, Iran. The investigators did not declare any conflicts of interest.

SOURCE: Safiri S et al. Ann Rheum Dis. 2019 Sep 11. doi: 10.1136/annrheumdis-2019-215920.

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