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Thyroid Status and 6‐Year Mortality in Elderly People Living in a Mildly Iodine‐Deficient Area: The Aging in the Chianti Area Study
Author(s) -
Ceresini Graziano,
Ceda Gian Paolo,
Lauretani Fulvio,
Maggio Marcello,
Usberti Elisa,
Marina Michela,
Bandinelli Stefania,
Guralnik Jack M.,
Valenti Giorgio,
Ferrucci Luigi
Publication year - 2013
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/jgs.12267
Subject(s) - medicine , euthyroid , subclinical infection , hazard ratio , confounding , proportional hazards model , confidence interval , thyroid function tests , thyroid function , thyroid , triiodothyronine , endocrinology
Objectives To test the hypothesis that, in older adults, living in a mildly iodine‐deficient area, thyroid dysfunction may be associated with mortality independent of potential confounders. Design Longitudinal. Setting Community‐based. Participants Nine hundred fifty‐one individuals aged 65 and older. Measurements Plasma thyrotropin, free thyroxine, and free triiodothyronine concentrations and demographic features were evaluated in participants of the Invecchiare in Chianti Study aged 65 and older. Participants were classified according to thyroid function test. Kaplan‐Meier survival and Cox proportional hazards models adjusted for confounders were used in the analysis. Results Eight hundred nineteen participants were euthyroid, 83 had subclinical hyperthyroidism ( SH yper), and 29 had subclinical hypothyroidism ( SH ypo). Overt hypo‐ and hyperthyroidism were found in five and 15 subjects, respectively. During a median of 6 years of follow‐up, 210 deaths occurred (22.1%), 98 (46.6%) of which were from cardiovascular causes. Kaplan‐Meier analysis revealed higher overall mortality for SH yper ( P = .04) than euthyroid subjects. After adjusting for multiple confounders, participants with SH yper (hazard ratio ( HR ) = 1.65, 95% confidence interval ( CI ) = 1.02–2.69) had significantly higher all‐cause mortality than those with normal thyroid function. No significant association was found between SH yper and cardiovascular mortality. In euthyroid subjects, thyrotropin was found to be predictive of lower risk of all‐cause mortality ( HR = 0.76, 95% CI = 0.57–0.99). Conclusion SH yper is an independent risk factor for all‐cause mortality in older adults. Low to normal circulating thyrotropin should be carefully monitored in elderly euthyroid individuals.