Anti-rheumatic drugs used for rheumatoid arthritis may help prevent autoimmune thyroid disease, according to a new observational study by researchers from Karolinska Institutet published in the *Journal of Internal Medicine*.
It is well known that patients with rheumatoid arthritis (RA) are at increased risk of developing autoimmune thyroid diseases such as Hashimoto's disease and Graves' disease. While RA patients are typically treated with immunomodulatory drugs, these medications are rarely used for autoimmune thyroid diseases, which are usually managed with thyroid hormone replacement to address abnormal thyroid function.
The researchers aimed to investigate whether immunomodulatory drugs that reduce joint inflammation in RA patients might also lower the risk of developing autoimmune thyroid disease. Previous studies in mice suggested that DMARDs (disease-modifying antirheumatic drugs), a type of immune-modulatory drug used to treat RA, can reduce thyroid gland inflammation. However, evidence of this effect in humans has been limited.
The study utilized data from 2006 to 2018 on over 13,000 RA patients and their treatments, as well as data from a matched control group of over 63,000 individuals without RA.
The findings showed that the risk of developing autoimmune thyroid disease among RA patients was lower after their diagnosis compared to before. The most significant reduction was observed in RA patients treated with immunomodulatory drugs or biological DMARDs, who had a 46 percent lower risk of autoimmune thyroid disease compared to the control group without RA.
"These results support the hypothesis that certain immunomodulatory drugs could have a preventive effect on autoimmune thyroid disease," says Kristin Waldenlind, a researcher at the Department of Medicine, Solna, Division of Clinical Epidemiology, Karolinska Institutet, and specialist in rheumatology at Karolinska University Hospital, and first author of the study. She continues:
"Our results do not conclusively prove that immunomodulatory drug treatment led to the reduced risk of autoimmune thyroid disease, but they support this hypothesis. If replicated in further studies, these findings could pave the way for clinical trials to explore whether the immunomodulatory drugs currently used for rheumatoid arthritis might also be effective for early treatment of autoimmune thyroid disease, indicating potential new uses for these drugs, known as drug repurposing."
