Subclinical hypothyroidism is associated with increased risk for all-cause and cardiovascular mortality in adults.

OBJECTIVES

This study sought to evaluate the relationship between subclinical hypothyroidism (SCH) and all-cause and cardiovascular disease (CVD) mortality.

BACKGROUND

SCH may increase the risks of hypercholesterolemia and atherosclerosis. The associations between SCH and all-cause or CVD mortality are uncertain, on the basis of the results of previous studies.

METHODS

A baseline cohort of 115,746 participants without a history of thyroid disease, ≥20 years of age, was recruited in Taiwan. SCH was defined as a serum thyroid-stimulating hormone (TSH) level of 5.0 to 19.96 mIU/l with normal total thyroxine concentrations. Euthyroidism was defined as a serum TSH level of 0.47 to 4.9 mIU/l. Cox proportional hazards regression analysis was used to estimate the relative risks (RRs) of death from all-cause and CVD for adults with SCH during a 10-year follow-up period.

RESULTS

There were 3,669 deaths during the follow-up period; 680 deaths were due to CVD. Compared with subjects with euthyroidism, after adjustment for age, sex, body mass index, diabetes, hypertension, dyslipidemia, smoking, alcohol consumption, betel nut chewing, physical activity, income, and education level, the RRs (95% confidence interval) of deaths from all-cause and CVD among subjects with SCH were 1.30 (1.02 to 1.66), and 1.68 (1.02 to 2.76), respectively.

CONCLUSIONS

Adult Taiwanese with SCH had an increased risk for all-cause mortality and CVD death.