High-Normal Thyroid Function Associated With Shorter Life, CVD
Individuals with low-normal thyroid function live longer compared with individuals with high-normal thyroid function, according to the findings of a recent study.
In their population-based cohort study, the researchers analyzed data from 7785 participants without known thyroid disease involved in the Rotterdam Study. The mean age of participants was 64.7 years and 52.5% of participants were women. Participants were stratified into tertiles based on their thyrotropin and free thyroxine (FT4) levels.
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The total life expectancy and the number of years lived with and without cardiovascular disease (CVD) were calculated using multistate life tables for thyrotropin and FT4 tertiles. In addition, the researchers estimated life expectancy for men and women aged 50 years or older using prevalence, incidence rates, and hazard ratios for 3 transitions: healthy to CVD, healthy to death, and CVD to death.
Over the median 8.1 years of follow-up, 789 incident CVD events and 1357 deaths occurred.
Men and women in the highest thyrotropin tertile lived 2 years and 1.4 years longer than those in the lowest tertile, respectively, and lived 1.5 years and 0.9 years longer without CVD.
The difference in life expectancy for men and women in the highest FT4 tertile compared with those in the lowest tertile was -3.2 and -3.5 years, respectively, of which -3.1 and -2.5 years were lived without CVD.
“At the age of 50 years, participants with low-normal thyroid function live up to 3.5 years longer overall and up to 3.1 years longer without CVD than participants with high-normal thyroid function,” the researchers concluded. “These findings provide supporting evidence for a reevaluation of the current reference ranges of thyroid function and can help inform preventive and clinical care.”
—Melissa Weiss
Reference:
Bano A, Dhana K, Chaker L, et al. Association of thyroid function with life expectancy with and without cardiovascular disease: the Rotterdam Study [published online September 18, 2017]. JAMA Intern Med. doi:10.1001/jamainternmed.2017.4836.