NEW YORK (Reuters Health)—Having a family history of rheumatoid arthritis (RA) does not appear to influence the clinical presentation or treatment response of RA to standard medications, researchers from Sweden report.
“At first we were a bit surprised by our findings,” Dr. Thomas Frisell from Karolinska Institutet in Stockholm told Reuters Health by email. “Patients with a family history of disease should on average have more of the genetic (and some non-genetic) risk factors for developing RA, and I would have guessed that this would be connected to a more severe or active disease, possibly more difficult to treat. In hindsight, the difference in genetic risk factors may not be very large, since all patients with RA are of course at increased levels of these risk factors, or they would not have developed the disease!”
Having a family history of RA increases the risk of RA threefold to fivefold, but whether such a family history influences the prognosis and treatment response once RA develops remains unclear.
Dr. Frisell’s team used data from the Swedish Rheumatology Quality of care register to assess if family history of RA is associated with a different clinical presentation of RA or if it predicts response to methotrexate or TNF inhibitor therapy.
Among more than 6,800 newly diagnosed patients, the 580 (8%) with at least one first-degree relative with RA were slightly more likely to have morning stiffness and slightly less likely to have arthritis in the hand or to have rheumatoid factor, compared with patients without a family history of RA.
There were no significant associations between family history of RA and any measure of response to methotrexate treatment, the researchers report in Annals of the Rheumatic Diseases, online June 19.
Similarly, family history of RA did not predict response to TNF inhibitor treatment three months after the start of such treatment. Slightly more patients with a family history of RA (13%) than without (11%) had switched treatment; among those remaining on treatment, family history of RA was associated with failure to achieve EULAR response. Disease activity changes, however, did not differ between patients with and without a family history of RA.
“Although weak associations can never be ruled out, we were able to reject a strong predictive value in overall family history of RA on the short-term response to either mono-methotrexate or TNF inhibitor therapy,” the researchers note. “We did find lower drug retention rate and EULAR response after 6 months on TNF inhibitors among those with family history of RA, but these associations were too weak to be useful in clinical decisions.”
