title: Subclinical hypothyroidism and the risk of heart failure, other cardiovascular events, and death.
abstract: BACKGROUND
  Subclinical hypothyroidism has been associated with systolic and diastolic cardiac dysfunction and an elevated cholesterol level, but data on cardiovascular outcomes and death are limited.
  
  
  METHODS
  We studied 2730 men and women, aged 70 to 79 years, with baseline thyrotropin (TSH) measurements and 4-year follow-up data to determine whether subclinical hypothyroidism was associated with congestive heart failure (CHF), coronary heart disease, stroke, peripheral arterial disease, and cardiovascular-related and total mortality. After the exclusion of participants with abnormal thyroxine levels, subclinical hypothyroidism was defined as a TSH level of 4.5 mIU/L or greater, and was further classified according to TSH levels (4.5-6.9, 7.0-9.9, and > or = 10.0 mIU/L).
  
  
  RESULTS
  Subclinical hypothyroidism was present in 338 (12.4%) of the participants. Compared with euthyroid participants, CHF events occurred more frequently among those with a TSH level of 7.0 mIU/L or greater (35.0 vs 16.5 per 1000 person-years; P = .006), but not among those with TSH levels between 4.5 and 6.9 mIU/L. In multivariate analyses, the risk of CHF was higher among those with high TSH levels (TSH of 7.0-9.9 mIU/L: hazard ratio, 2.58 [95% confidence interval, 1.19-5.60]; and TSH of > or = 10.0 mIU/L: hazard ratio, 3.26 [95% confidence interval, 1.37-7.77]). Among the 2555 participants without CHF at baseline, the hazard ratio for incident CHF events was 2.33 (95% confidence interval, 1.10-4.96; P = .03) in those with a TSH of 7.0 mIU/L or greater. Subclinical hypothyroidism was not associated with increased risk for coronary heart disease, stroke, peripheral arterial disease, or cardiovascular-related or total mortality.
  
  
  CONCLUSIONS
  Subclinical hypothyroidism is associated with an increased risk of CHF among older adults with a TSH level of 7.0 mIU/L or greater, but not with other cardiovascular events and mortality. Further investigation is warranted to assess whether subclinical hypothyroidism causes or worsens preexisting heart failure.
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco, USA. Nicolas.Rodondi@hospvd.ch
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rodondi
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.forename: Nathalie
authors.initials: N
authors.lastname: de Rekeneire
authors.forename: Suzanne
authors.initials: S
authors.lastname: Satterfield
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Bauer
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000097:blood / Q000209:etiology* / Q000401:mortality; D015415:Biomarkers / Q000097:blood; D003327:Coronary Disease / Q000097:blood / Q000209:etiology* / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000209:etiology* / Q000401:mortality; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications*; D007118:Immunoassay; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000097:blood / Q000209:etiology* / Q000401:mortality; D015996:Survival Rate / Q000639:trends; D013972:Thyrotropin / Q000097:blood
chemical_list: D015415:Biomarkers; D013972:Thyrotropin