@article {1231, title = {Subclinical hypothyroidism and the risk of coronary heart disease and mortality.}, journal = {JAMA}, volume = {304}, year = {2010}, month = {2010 Sep 22}, pages = {1365-74}, abstract = {

CONTEXT: Data regarding the association between subclinical hypothyroidism and cardiovascular disease outcomes are conflicting among large prospective cohort studies. This might reflect differences in participants{\textquoteright} age, sex, thyroid-stimulating hormone (TSH) levels, or preexisting cardiovascular disease.

OBJECTIVE: To assess the risks of coronary heart disease (CHD) and total mortality for adults with subclinical hypothyroidism.

DATA SOURCES AND STUDY SELECTION: The databases of MEDLINE and EMBASE (1950 to May 31, 2010) were searched without language restrictions for prospective cohort studies with baseline thyroid function and subsequent CHD events, CHD mortality, and total mortality. The reference lists of retrieved articles also were searched.

DATA EXTRACTION: Individual data on 55,287 participants with 542,494 person-years of follow-up between 1972 and 2007 were supplied from 11 prospective cohorts in the United States, Europe, Australia, Brazil, and Japan. The risk of CHD events was examined in 25,977 participants from 7 cohorts with available data. Euthyroidism was defined as a TSH level of 0.50 to 4.49 mIU/L. Subclinical hypothyroidism was defined as a TSH level of 4.5 to 19.9 mIU/L with normal thyroxine concentrations.

RESULTS: Among 55,287 adults, 3450 had subclinical hypothyroidism (6.2\%) and 51,837 had euthyroidism. During follow-up, 9664 participants died (2168 of CHD), and 4470 participants had CHD events (among 7 studies). The risk of CHD events and CHD mortality increased with higher TSH concentrations. In age- and sex-adjusted analyses, the hazard ratio (HR) for CHD events was 1.00 (95\% confidence interval [CI], 0.86-1.18) for a TSH level of 4.5 to 6.9 mIU/L (20.3 vs 20.3/1000 person-years for participants with euthyroidism), 1.17 (95\% CI, 0.96-1.43) for a TSH level of 7.0 to 9.9 mIU/L (23.8/1000 person-years), and 1.89 (95\% CI, 1.28-2.80) for a TSH level of 10 to 19.9 mIU/L (n = 70 events/235; 38.4/1000 person-years; P <.001 for trend). The corresponding HRs for CHD mortality were 1.09 (95\% CI, 0.91-1.30; 5.3 vs 4.9/1000 person-years for participants with euthyroidism), 1.42 (95\% CI, 1.03-1.95; 6.9/1000 person-years), and 1.58 (95\% CI, 1.10-2.27, n = 28 deaths/333; 7.7/1000 person-years; P = .005 for trend). Total mortality was not increased among participants with subclinical hypothyroidism. Results were similar after further adjustment for traditional cardiovascular risk factors. Risks did not significantly differ by age, sex, or preexisting cardiovascular disease.

CONCLUSIONS: Subclinical hypothyroidism is associated with an increased risk of CHD events and CHD mortality in those with higher TSH levels, particularly in those with a TSH concentration of 10 mIU/L or greater.

}, keywords = {Adolescent, Adult, Aged, Aged, 80 and over, Coronary Disease, Female, Humans, Hypothyroidism, Male, Middle Aged, Mortality, Prospective Studies, Risk, Thyrotropin, Young Adult}, issn = {1538-3598}, doi = {10.1001/jama.2010.1361}, author = {Rodondi, Nicolas and den Elzen, Wendy P J and Bauer, Douglas C and Cappola, Anne R and Razvi, Salman and Walsh, John P and Asvold, Bj{\o}rn O and Iervasi, Giorgio and Imaizumi, Misa and Collet, Tinh-Hai and Bremner, Alexandra and Maisonneuve, Patrick and Sgarbi, Jos{\'e} A and Khaw, Kay-Tee and Vanderpump, Mark P J and Newman, Anne B and Cornuz, Jacques and Franklyn, Jayne A and Westendorp, Rudi G J and Vittinghoff, Eric and Gussekloo, Jacobijn} } @article {1545, title = {Subclinical hyperthyroidism and the risk of coronary heart disease and mortality.}, journal = {Arch Intern Med}, volume = {172}, year = {2012}, month = {2012 May 28}, pages = {799-809}, abstract = {

BACKGROUND: Data from prospective cohort studies regarding the association between subclinical hyperthyroidism and cardiovascular outcomes are conflicting.We aimed to assess the risks of total and coronary heart disease (CHD) mortality, CHD events, and atrial fibrillation (AF) associated with endogenous subclinical hyperthyroidism among all available large prospective cohorts.

METHODS: Individual data on 52 674 participants were pooled from 10 cohorts. Coronary heart disease events were analyzed in 22 437 participants from 6 cohorts with available data, and incident AF was analyzed in 8711 participants from 5 cohorts. Euthyroidism was defined as thyrotropin level between 0.45 and 4.49 mIU/L and endogenous subclinical hyperthyroidism as thyrotropin level lower than 0.45 mIU/L with normal free thyroxine levels, after excluding those receiving thyroid-altering medications.

RESULTS: Of 52 674 participants, 2188 (4.2\%) had subclinical hyperthyroidism. During follow-up, 8527 participants died (including 1896 from CHD), 3653 of 22 437 had CHD events, and 785 of 8711 developed AF. In age- and sex-adjusted analyses, subclinical hyperthyroidism was associated with increased total mortality (hazard ratio[HR], 1.24, 95\% CI, 1.06-1.46), CHD mortality (HR,1.29; 95\% CI, 1.02-1.62), CHD events (HR, 1.21; 95\%CI, 0.99-1.46), and AF (HR, 1.68; 95\% CI, 1.16-2.43).Risks did not differ significantly by age, sex, or preexisting cardiovascular disease and were similar after further adjustment for cardiovascular risk factors, with attributable risk of 14.5\% for total mortality to 41.5\% forAF in those with subclinical hyperthyroidism. Risks for CHD mortality and AF (but not other outcomes) were higher for thyrotropin level lower than 0.10 mIU/L compared with thyrotropin level between 0.10 and 0.44 mIU/L(for both, P value for trend, .03).

CONCLUSION: Endogenous subclinical hyperthyroidism is associated with increased risks of total, CHD mortality, and incident AF, with highest risks of CHD mortality and AF when thyrotropin level is lower than 0.10 mIU/L.

}, keywords = {Adolescent, Adult, Age Distribution, Aged, Aged, 80 and over, Atrial Fibrillation, Cause of Death, Cohort Studies, Coronary Artery Disease, Female, Humans, Hyperthyroidism, Male, Middle Aged, Prognosis, Prospective Studies, Risk Assessment, Severity of Illness Index, Sex Distribution, Survival Analysis, Switzerland, Thyroid Function Tests, Thyrotropin, Young Adult}, issn = {1538-3679}, doi = {10.1001/archinternmed.2012.402}, author = {Collet, Tinh-Hai and Gussekloo, Jacobijn and Bauer, Douglas C and den Elzen, Wendy P J and Cappola, Anne R and Balmer, Philippe and Iervasi, Giorgio and Asvold, Bj{\o}rn O and Sgarbi, Jos{\'e} A and V{\"o}lzke, Henry and Gencer, Bari{\c s} and Maciel, Rui M B and Molinaro, Sabrina and Bremner, Alexandra and Luben, Robert N and Maisonneuve, Patrick and Cornuz, Jacques and Newman, Anne B and Khaw, Kay-Tee and Westendorp, Rudi G J and Franklyn, Jayne A and Vittinghoff, Eric and Walsh, John P and Rodondi, Nicolas} }