Subclinical hypothyroidism and cardiovascular risk

January 01, 0001

Subclinical hypothyroidism and cardiovascular risk

There has been conflicting data linking subclinical hypothyroidism and cardiovascular disease. This international group of researchers assessed the risks of coronary heart disease (CHD) and total mortality with subclinical hypothyroidism. They performed a systematic review usind MEDLINE and EMBASE (1950 to May 31, 2010) without language restrictions yielding 11 prospective cohort studies on this topic. The reference lists of retrieved articles also were searched. Data on 55 287 participants with 542 494 person-years of follow-up were garnered. The risk of CHD events was examined in 25 977 participants from 7 cohorts with available data.

The researchers found: "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 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 for a TSH level of 7.0 to 9.9 mIU/L (23.8/1000 person-years), and 1.89 for a TSH level of 10 to 19.9 mIU/L (n = 70 events/235, 38.4/1000 person-years). The corresponding HRs for CHD mortality were 1.09 (5.3 vs 4.9/1000 person-years for participants with euthyroidism), 1.42 (6.9/1000 person-years), and 1.58 (n = 28 deaths/333, 7.7/1000 person-year). 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."

The researchers concluded: "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."

This systematic review and meta-analysis finds for increased cardiovascular risk with subclinical hypothyroidism

For the full abstract, click here.

JAMA 304 (12): 1365-1374, 22 September 2010
© 2010 American Medical Association
Subclinical Hypothyroidism and the Risk of Coronary Heart Disease and Mortality. Nicolas Rodondi, Wendy P. J. den Elzen, Douglas C. Bauer.

Category: K. Circulatory, T. Endocrine/Metabolic/Nutritional. Keywords: subclinical hypothyroidism, cardiovascular risk, coronary artery disease, TSH, mortality, systematic review and meta-analysis, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 5 October 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.