Long‐term outcomes in seronegative rheumatoid arthritis

Objective The purpose of this study was to determine the cumulative incidence of diagnosis switching, drug‐free remission, and initiation of a biologic or targeted synthetic disease modifying anti‐rheumatic drug (b/tsDMARD) in individuals with seronegative RA. Methods Adult residents of Olmsted County, MN with incident seronegative (rheumatoid factor‐/anti‐cyclic citrullinated peptide antibody‐) RA meeting the 1987 and/or 2010 American College of Rheumatology classification criteria were included. Data were collected from 1/1/2005‐12/31/2023 through manual chart review. Drug‐free remission was defined as a period of ≥6 months where the individual was no longer on treatment for RA and did not have evidence of active inflammatory arthritis on evaluation by a rheumatologist. We calculated the 10‐year cumulative incidence of a change in diagnosis, adjusting for the competing risk of death, and of drug‐free remission and initiation of a b/tsDMARD, adjusting for the competing risks of death or change in diagnosis. Results A total of 176 individuals with seronegative RA (68% female) were included. The 10‐year cumulative incidence of a change in diagnosis was 12.8% (95% confidence interval (CI): 8.7‐18.9%). The most common change in diagnosis was to a spondyloarthritis (4%). The 10‐year cumulative incidence of drug‐free remission and initiation of a b/tsDMARD was 26.6% (95% CI: 20.7‐34.2%) and 19.9% (95% CI: 14.7‐26.9%), respectively. Over a median follow‐up of 11.8 years, 49 individuals entered drug‐free remission. Conclusions After initial diagnosis of seronegative RA, about 13% of individuals had a change in diagnosis and a quarter experienced drug‐free remission within 10 years.