Anne R. Cappola, M.D., Sc.M., of the University of Pennsylvania School of Medicine, Philadelphia, and colleagues tested the hypothesis that abnormal thyroid status is associated with increased cardiovascular risk and death in individuals with unrecognized thyroid dysfunction. The study included 3,233 U.S. individuals aged 65 years or older who had their serum thyroid-stimulating hormone levels measured when enrolled in 1989-1990. The cardiovascular health of the patients, who were not taking thyroid medication, was assessed through June 2002.
The researchers found that 82 percent of participants had normal thyroid function, 15 percent had subclinical (before symptoms) hypothyroidism (an underactive thyroid gland), 1.6 percent had symptomatic hypothyroidism, and 1.5 percent had subclinical hyperthyroidism (an overactive thyroid gland). After exclusion of those who had atrial fibrillation at the start of the study, individuals with subclinical hyperthyroidism had nearly twice the incidence of developing atrial fibrillation compared with those with normal thyroid function. No differences were seen between the subclinical hyperthyroidism group and the normal thyroid function group for the occurrence of coronary heart disease, cerebrovascular disease, cardiovascular death, or all-cause death.
“Our analyses do not support screening older individuals solely to prevent atrial fibrillation, with an estimated number needed to screen of 2,500 older individuals to find 1 case of atrial fibrillation associated with subclinical hyperthyroidism. Our findings suggest that if endogenous [originating from within the thyroid] subclinical hyperthyroidism is detected, older individuals may benefit from treatment to prevent atrial fibrillation,� the authors write. “Our analyses do not support screening older individuals for thyroid disease to prevent CVD, and, although our data are observational, they do not support treatment of individuals with subclinical hypothyroidism to prevent cardiovascular events.�
Sources:
- Cappola, Anne R. MD, et. al. "Thyroid Status, Cardiovascular Risk, and Mortality in Older Adults," JAMA 2006;295:1033-1041 -- Vol. 295 No. 9, March 1, 2006
- Newswise
