Thyroid hormone use, hyperthyroidism and mortality in older women.
OBJECTIVE
Thyroid dysfunction is common, particularly among older women. The safety of thyroid hormone use and long-term prognosis of hyperthyroidism remain controversial. We performed a prospective cohort study to examine the relationship among thyroid hormone use, previous hyperthyroidism, abnormal thyroid function, and mortality.


METHODS
We studied 9449 community-dwelling white women aged > or =65 years followed for 12 years. For analyses of thyroid function, we performed a nested case-cohort in 487 women using a third-generation thyroid-stimulating hormone assay. Causes of death were adjudicated based on death certificates and hospital records.


RESULTS
Twelve percent of the 9449 women took thyroid hormone at baseline, and the mean duration of thyroid hormone use was 15.8 years; 9.4% of participants reported a history of hyperthyroidism. During 12 years of follow-up, 3159 women died (33%). In multivariate analysis, mortality among users of thyroid hormone was similar to that observed for nonusers (relative hazard [RH] 1.11, 95% confidence interval [CI], 0.98-1.24, P=.09). Previous hyperthyroidism was associated with a higher risk of all-cause mortality (RH 1.20, 95% CI, 1.06-1.36), particularly cardiovascular mortality (RH 1.46, 95% CI, 1.20-1.77). Low (< or /=0.5 mU/L) or high (>5 mU/L) thyroid-stimulating hormone levels were not associated with excess total or cause-specific mortality, but the power to detect these relationships was limited.


CONCLUSIONS
Among older women, thyroid hormone use is not associated significantly with excess mortality, but previous hyperthyroidism may be associated with a small increase in all-cause and cardiovascular mortality. Additional long-term studies of hyperthyroidism and its treatment should further explore these findings.
Bauer
Douglas C
DC
Division of General Internal Medicine, University of California, San Francisco, CA 94107, USA. dbauer@psg.ucsf.edu
Rodondi
Nicolas
N
Stone
Katie L
KL
Hillier
Teresa A
TA
D017677:Age Distribution; D000368:Aged; D001835:Body Weight; D002318:Cardiovascular Diseases / Q000401:mortality; D016022:Case-Control Studies; D002423:Cause of Death; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D006980:Hyperthyroidism / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality*; D008019:Life Style; D015999:Multivariate Analysis; D009369:Neoplasms / Q000401:mortality; D011446:Prospective Studies; D012307:Risk Factors; D013963:Thyroid Hormones / Q000627:therapeutic use*; D013972:Thyrotropin / Q000378:metabolism; D014481:United States / Q000453:epidemiology
D013963:Thyroid Hormones; D013972:Thyrotropin