title: Subclinical hypothyroidism and risk for incident myocardial infarction among postmenopausal women.
abstract: BACKGROUND
  Subclinical hypothyroidism (SCH) has been associated with an increased risk for cardiovascular disease. However, few studies have specifically examined the association between SCH and myocardial infarction (MI), and the relationship is poorly understood.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate incident MI risk in relation to SCH and severities of SCH among postmenopausal women.
  
  
  METHODS
  We used a population-based nested case-cohort design within the Women's Health Initiative observational study to examine the association between SCH and incident first-time MI risk among postmenopausal women in the United States. SCH was assessed using blood specimens collected at baseline. Participants presenting with normal free T4 levels and with thyrotropin levels of greater than 4.68-6.99 mU/L or 7.00 mU/L or greater were defined as having mild SCH or moderate/severe SCH, respectively. MI cases were centrally adjudicated by trained Women's Health Initiative staff. The primary analysis included 736 incident MI cases and 2927 randomly selected subcohort members. Multivariable adjusted Cox-proportional hazard models were used to assess MI risk in relation to SCH.
  
  
  RESULTS
  Compared with euthyroid participants, the multivariable adjusted hazard ratio (HR) for participants with any SCH was 1.05 [95% confidence interval (CI) 0.77-1.44]. HRs for participants with mild SCH, moderate/severe SCH, and moderate/severe SCH and the presence of antithyroid peroxidase antibodies (TPOAb) were 0.99 (95% CI 0.67-1.46), 1.19 (95% CI 0.72-1.96), and 0.90 (95% CI 0.47-1.74), respectively.
  
  
  CONCLUSIONS
  We did not find evidence to suggest that SCH is associated with increased MI risk among a population of predominantly older postmenopausal women with no prior history of MI.
authors.affiliation: Division of Clinical Laboratory Science, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Vicky A
authors.initials: VA
authors.lastname: LeGrys
authors.forename: Michele Jonsson
authors.initials: MJ
authors.lastname: Funk
authors.forename: Carol E
authors.initials: CE
authors.lastname: Lorenz
authors.forename: Ayush
authors.initials: A
authors.lastname: Giri
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Jackson
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Robin
authors.initials: R
authors.lastname: Schectman
authors.forename: Todd L
authors.initials: TL
authors.lastname: Edwards
authors.forename: Gerardo
authors.initials: G
authors.lastname: Heiss
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hartmann
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology*; D017698:Postmenopause; D016016:Proportional Hazards Models; D012306:Risk; D013972:Thyrotropin / Q000097:blood
chemical_list: D013972:Thyrotropin
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