Meta-Analysis
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World J Meta-Anal. Aug 26, 2013; 1(2): 90-96
Published online Aug 26, 2013. doi: 10.13105/wjma.v1.i2.90
Subclinical hypothyroidism and the metabolic syndrome: A meta-analysis of cross-sectional studies
Yi-Cong Ye, Hong-Zhi Xie, Xi-Liang Zhao, Shu-Yang Zhang
Yi-Cong Ye, Hong-Zhi Xie, Xi-Liang Zhao, Shu-Yang Zhang, Department of Cardiology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China
Author contributions: Zhang SY contributed to the concept design, data analysis and manuscript revision; Ye YC and Xie HZ contributed to the database search, study selection, quality assessment, statistic analysis, data interpretation and drafting the manuscript; Zhao XL contributed to data analysis and drafting the manuscript.
Correspondence to: Dr. Shu-Yang Zhang, Department of Cardiology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Dongcheng District Dongdansantiao, Beijing 100730, China. zhangebmg@gmail.com
Telephone: +86-10-69155068 Fax: +86-10-69155068
Received: February 20, 2013
Revised: May 23, 2013
Accepted: June 1, 2013
Published online: August 26, 2013
Abstract

AIM: To determine the relationship between subclinical hypothyroidism (SCH) and the metabolic syndrome (MS).

METHODS: We performed a systematic search of databases [MEDLINE (July 1950 to July 2012), EMBASE (July 1966 to July 2012)] and the references of identified studies. Completely published cross-sectional studies of a general population involving SCH and the MS were included. The pooled odds ratio and weighted mean difference (WMD) for the outcomes were calculated using random-effects models.

RESULTS: Six cross-sectional studies with 19546 participants were included. In total, 398 of 1324 participants (30.06%) in the SCH group had the MS compared with 4975 of 18222 participants (27.30%) in the euthyroid group [OR = 1.20; 95%CI: 1.05-1.36; P = 0.004; χ2 = 2.53 (P = 0.773); I2 = 0%]. Further analysis of the components of the MS showed that SCH was associated with increased body mass index (WMD, 0.32 kg/m2; 95%CI: 0.04-0.61; P = 0.026), systolic blood pressure (WMD, 2.62 mmHg; 95%CI: 1.35-3.89; P < 0.001) and triglyceride (WMD, 0.25 mmol/L; 95%CI: 0.23-0.28; P < 0.001).

CONCLUSION: Based on the cross-sectional data, SCH may be associated with an increased risk of the MS, which could be attributed to the increased risk of metabolic components.

Keywords: Subclinical hypothyroidism, Metabolic syndrome, Meta-analysis

Core tip: A recent meta-analysis of individual data concluded that subclinical hypothyroidism (SCH) is associated with an increased risk of coronary heart disease (CHD) and CHD mortality. Meanwhile, it has been well recognized that the metabolic syndrome (MS) is associated with increased cardiovascular events and all-cause mortality. Our meta-analysis of cross-sectional data demonstrated that SCH may be associated with an increased risk of the MS, which may explain the relationship between SCH and increased risk of CHD.