WASHINGTON – Seropositivity for either rheumatoid factor or anti-cyclic citrullinated peptide was significantly associated with progressive joint damage in adults with established rheumatoid arthritis, based on a single-center, observational cohort study of 390 patients.
Most rheumatoid arthritis (RA) patients in clinical practice have established disease, but the predictors and proportion of disease progression in these patients has not been well studied, Dr. Siri Lillegraven of Diakonhjemmet Hospital in Oslo said at the annual meeting of the American College of Rheumatology.
Dr. Lillegraven and her colleagues reviewed data from BRASS (the Brigham and Women’s Hospital Rheumatoid Arthritis Sequential Study). Joint damage was assessed using baseline and 2-year radiographic data for patients with disease duration of at least 5 years. The average age of the patients was 60 years, 84% were women, and 44% received biologic treatment in the form of disease-modifying antirheumatic drugs (DMARDs). The median disease duration was 17 years. Disease progression was defined as a change in Sharp/van der Heijde score of 1 or more units per year.
Overall, 44% of the patients showed disease progression after 2 years. A total of 68% of the patients were positive for both rheumatoid factor (RF) and anticyclic citrullinated peptide (anti-CCP), 16% were positive for either RF or anti-CCP, and 16% were negative for both.
Seropositivity was the only significant independent predictor of disease progression after controlling for factors including age, gender, body-mass index, smoking status, treatment, DMARD use, disease duration, and presence of subcutaneous nodules, Dr. Lillegraven said.
Patients who were seropositive for either RF or anti-CCP were five times more likely than were seronegative patients to have disease progression (odds ratio 5.0), while seropositivity for both was associated with four times greater odds for disease progression (odds ratio 4.1).
"Although the odds ratios for progressive joint damage were similar if patients were positive for one or both of RF and anti-CCP, patients who were positive for both RF and anti-CCP tended to experience more joint damage," Dr. Lillegraven said. Rapid progression of joint damage (defined as a change in van der Heijde-Sharp score of 5 or more units per year) was noted in 16% patients who were seropositive for both RF and anti-CCP, compared with 9% of those who were positive for either RF or anti-CCP, although this difference was not statistically significant.
The results were limited by the use of data from a single center and by the challenge of fully adjusting for treatment in patients with established RA, Dr. Lillegraven noted. However, the findings suggest that seropositivity could be used to inform treatment decisions for these patients, she said.
Dr. Lillegraven had no financial conflicts to disclose. Several of the study coauthors disclosed relationships with multiple pharmaceutical companies, including Amgen, Abbott, Merck, and MedImmune.