Over the last 3 decades, there has been a significant decline in the incidence of rheumatoid factor (RF)-positive rheumatoid arthritis (RA), while the overall incidence of rheumatoid arthritis has remained about the same, researchers report. "These trends may suggest changing serological profile of RA over time which may have implications for RA diagnosis and management," Dr. Elena Myasoedova of Mayo Clinic, in Rochester, Minnesota, told Reuters Health by email. For their study, published in the Annals of the Rheumatic Diseases, Dr. Myasoedova and colleagues used data from the Rochester Epidemiology Project medical-record-linkage system. Overall, the age-adjusted and sex-adjusted annual incidence of RA per 100,000 in 2005-2014 was 41, with an incidence of 53 in women and 29 in men, estimates that were similar to the previous decades. The proportion of RF-positive RA declined significantly from 69% in the earlier decades to 51% in the 2005-2014 group (P<0.001), with a corresponding increase in the proportion of RF-negative RA. The prevalence of erosive disease remained stable among patients with RF-positive RA while the proportion of erosive disease in RF-negative RA rose in 2005-2014 compared with the prior decades. "Seronegative RA can be challenging to diagnose, which may delay treatment initiation and negatively impact the outcomes," Dr. Myasoedova said. "The increasing incidence of RF-negative RA suggests the need for increased awareness and timely recognition of this subset of RA by physicians." "Future studies should investigate the underlying reasons for these trends in RA incidence in order to extend understanding of the risk factors for seropositive and particularly for seronegative RA," she said. —Will Boggs MD Source
