Subclinical hypothyroidism and the risk of coronary heart disease: a meta-analysis.
OBJECTIVE
Subclinical hypothyroidism has been associated with elevated cholesterol and increased risk for atherosclerosis, but data on the risk of coronary heart disease (CHD) are conflicting. We performed a systematic review to determine whether subclinical hypothyroidism is associated with CHD in adults.


METHODS
We searched MEDLINE from 1966 to April 2005, and the bibliographies of key articles to identify studies that provided risk estimates for CHD or cardiovascular mortality associated with subclinical hypothyroidism. Two authors independently reviewed each potential study for eligibility, assessed methodologic quality, and extracted the data.


RESULTS
We identified 14 observational studies that met eligibility criteria. Subclinical hypothyroidism increased the risk of CHD (summary odds ratio [OR]: 1.65, 95% confidence interval [CI], 1.28-2.12). The summary OR for CHD was 1.81 (CI, 1.38-2.39) in 9 studies adjusted or matched for demographic characteristics, and 2.38 (CI, 1.53-3.69) after pooling the studies that adjusted for most cardiovascular risk factors. Sensitivity analyses including only population-based studies and those with formal outcome adjudication procedures yielded similar results. Subgroup analyses by type of study design showed a similar trend, but lower risk, in the 5 prospective cohort studies (OR 1.42, CI, 0.91-2.21), compared with the case-control and cross-sectional studies (OR 1.72, CI, 1.25-2.38).


CONCLUSIONS
Our systematic review indicates that subclinical hypothyroidism is associated with an increased risk of CHD. Clinical trials are needed to assess whether thyroxine replacement reduces the risk of CHD in subjects with subclinical hypothyroidism.
Rodondi
Nicolas
N
Department of Epidemiology and Biostatistics, University of California, San Francisco, USA. Nicolas.Rodondi@hospvd.ch
Aujesky
Drahomir
D
Vittinghoff
Eric
E
Cornuz
Jacques
J
Bauer
Douglas C
DC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000150:complications / Q000209:etiology; D002784:Cholesterol / Q000097:blood; D003327:Coronary Disease / Q000209:etiology*; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000175:diagnosis; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors
D002784:Cholesterol