Regardless of rheumatoid factor status, the risk of hypothyroidism is increased among rheumatoid arthritis patients who are already in the disease onset, especially among young women, according to study results.
Using a Finnish nationwide register of special reimbursements for medication costs, researchers identified 7,209 incident patients with rheumatoid arthritis (RA) diagnosed between January 2004 and December 2007, as well as the presence of hypothyroidism at RA diagnosis based on special reimbursement decisions for levothyroxine substitution. Researchers compared the prevalence of levothyroxine-treated hypothyroidism to an age- and sex-specific Finnish population and calculated a standardized rate ratio for hypothyroidism.
Study results showed a standardized rate ratio of 1.51 for levothyroxine-treated hypothyroidism preceding RA. Researchers found that neither rheumatoid factor status nor sex modified the risk. However, results did not reach statistical significance among men. Among younger female RA patients, standardized rate ratio was highest, almost 2.5, with the excess prevalence of hypothyroidism decreasing steadily and wearing off among patients who were older at the time of diagnosis, according to study results. Similar to the general population, the absolute prevalence of hypothyroidism increased with age.
Disclosure: The authors have no relevant financial disclosures.