Rheumatoid arthritis is associated with a high prevalence of hypothyroidism that amplifies its cardiovascular risk.

Objective: Rheumatoid arthritis (RA) patients have an increased risk of developing cardiovascular diseases (CVD). Other autoimmune diseases such as hypothyroidism are also associated with an enhanced risk for CVD. Our objective was to determine first, the prevalence of hypothyroid disorders in RA patients, and second, the risk of CVD in RA patients with hypothyroid abnormalities.
Subjects: were RA patients who participated in an ongoing prospective cohort study of cardiovascular mortality and morbidity (n = 358) in which hypothyroid abnormalities were assessed. CVD was defined as a verified medical history of coronary, cerebral or peripheral arterial disease.
Results: Clinical hypothyroidism was observed in 16 of 236 female RA patients (6.8%), which is significantly higher than in the general population of The Netherlands. Subclinical hypothyroidism was detected in 6 out of 236 RA women (2.5%). In female RA patients, CVD was present in 6 out of 16 (37.5%) of all hypothyroid women. The odds ratio for CVD comparing female hypothyroid RA patients with female euthyroid RA patients was 4.1 (95% CI 1.2-14.3) after adjustment for sex, age, diabetes, smoking (ever), hypertension and statin use.
Conclusions: Clinical hypothyroidism was observed three times more often in female RA patients than females in the general population. In female RA patients, clinical hypothyroidism was associated with a fourfold higher risk of CVD in comparison with euthyroid female RA patients independently of the traditional risk factors.