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Repeat serologies in RA after initial negative response may be needed
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DESTIN, Fla. — Significantly higher than expected rates of patients with inflammatory arthritis, who were serologically negative for rheumatoid arthritis, seroconvert within 2 to 4 years, according to data presented at the 2019 North American Young Rheumatology Investigator Forum.
“Autoantibodies, including rheumatoid factor and anticitrullinated protein antibody, have been shown to have clinical implications both diagnostically and prognostically in patients with rheumatoid arthritis,” Ricky Mehta, MD, of the University of Kansas Medical Center, told attendees. “Both RF and ACPA are part of the 2010 ACR/EULAR classification criteria for RA. ACPA is also highly specific for rheumatoid arthritis. It is well recognized that early diagnosis and initiation of DMARD therapy leads to better clinical outcomes and reduction of joint damage and disability. Moreover, presence of RF has been associated with an increased risk of extra-articular manifestations.”
“However, these autoantibodies can be absent in a subset of patients with rheumatoid arthritis,” Mehta added. “There have been some studies demonstrating that a small number of patients seroconverted over time. Though whether change in these markers occurs in seropositive patients over time has been studied, there was heterogeneity in the results.”
To examine the rates of patients with an initial diagnosis of inflammatory arthritis who seroconverted over a decade, Mehta and colleagues conducted a retrospective chart review of individuals at a single, tertiary medical center included in the HERON database. Specifically, the researchers focused on patients with diagnosis codes for inflammatory arthritis who had at least two values for rheumatoid factor and anticitrullinated protein antibodies.
Among the 2,025 patients in the rheumatoid factor category, 168 had at lest two values measured. Among the 1,511 patients included in the anticitrullinated protein antibody category, 61 had two values measured.
According to Mehta, 37.5% of patients who tested seronegative for rheumatoid factor, and 26.2% of those who were serologically negative for anticitrullinated protein antibodies, later seroconverted. Seroconversions in the rheumatoid factor category occurred within a mean of 1,404.7 days, while those in the anticitrullinated protein antibody group seroconverted within a mean of 949 days.
However, Mehta also noted that 24 of the 63 patients in the rheumatoid factor group who had seroconverted had other potential explanations for their newly positive titer — including cancer, hepatitis C, vasculitis, Crohn’s disease and other connective tissue diseases — resulting in a new conversion rate of 23%. In the anticitrullinated protein antibody group, five of the 16 patients who converted also had other potential explanations, including current or former tobacco use, resulting in a new seroconversion rate of 18%
“When you look at previous studies, the seroconversion rates were significantly higher in our study,” Mehta said. “Repeat serologies after about 3 or 4 years after the initial RF and ACPA were negative in patients with inflammatory arthritis may be a reasonable approach, particularly if it may affect therapeutic decision making.”
“A proportion of patients that did seroconvert had a change in therapy, which may reflect the physician’s confidence in the diagnosis, because that can be a little bit difficult to say for sure that someone has rheumatoid arthritis if they are seronegative,” he added. “Additional long-term prospective studies should be performed to further investigate these findings.” – by Jason Laday
Reference:
Mehta R. Should rheumatoid factor and anti-CCP antibodies be repeated in patients with a diagnosis of seronegative inflammatory arthritis? Presented at: North American Young Rheumatology Investigator Forum; May 1, 2019; Destin, Fla.
Disclosure: Mehta reports no relevant financial disclosures.