To determine the frequency of hypothyroidism in patients with rheumatoid arthritis (RA), and to elucidate the association of hypothyroidism and development of cardiovascular disease (CVD) in these patients.
A retrospective medical record review was performed using all incident cases of adult-onset RA from Olmsted County, MN, USA, that fulfilled criteria for RA in the years 1988-2007. Patients with and without thyroid disease were followed longitudinally for the development of CVD.
A cohort of 650 patients with RA and an age and sex-matched comparison cohort of 650 patients without RA was assembled (both cohorts mean age 55.8 yrs; 69% were women). There was no significant difference between cohorts in the presence of hypothyroid disease or subclinical hypothyroidism at time of RA diagnosis. No significant difference was found in the cumulative incidence of hypothyroid disease between the 2 cohorts. Hypothyroid disease was found to be significantly associated with CVD in patients with RA (hazard ratio 2.0; 95% CI 1.1, 3.6). This difference remained significant and unchanged after adjustment for traditional CV risk factors (HR 2.0; 95% CI 1.1, 3.6).
No significant difference was found in either incidence or prevalence of hypothyroidism between patients with and those without RA. Hypothyroid disease was significantly associated with CVD in patients with RA, even after adjustment for other traditional CV risk factors.