Objectives To assess the relationship between subclinical hyperthyroidism and the incidence of coronary heart disease (CHD). Methods PubMed, EMbase, The Cochrane Library, Web of Science, CNKI, VIP, WanFang Data and CBM databases were searched for studies on the relationship between subclinical hyperthyroidism and the incidence of CHD from inception to October 2016. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. Then, meta-analysis was performed by using RevMan 5.3 and Stata 12.0 software. Results In total, 14 cohort studies were included. The results of meta-analysis showed that subclinical hyperthyroidism was associated with the incidence of coronary heart disease (RR=1.19, 95%CI 1.01 to 1.40, P=0.04) and all-cause mortality (RR=1.36, 95%CI 1.11 to 1.67, P=0.003). Conclusions Subclinical hyperthyroidism is associated with an increased risk of CHD and all-cause mortality. Due to the limitation of quality and quantity of the studies, the above conclusions are required to be verified by large-scale and high quality research.
ObjectiveTo systematically review the relationship between subclinical thyroid dysfunction and the risk of atrial fibrillation.MethodsDatabases including PubMed, EMbase, The Cochrane Library, Web of Science, CNKI, CBM, VIP and WanFang Data were electronically searched to collect cohort studies on associations between subclinical thyroid dysfunction and atrial fibrillation from inception to June 2020. Two reviewers independently screened literature, extracted data, and evaluated risk of bias of included studies. Meta-analysis was then performed using RevMan 5.3 software.ResultsA total of 11 studies involving 620 874 subjects and 19 781 cases were included. Meta-analysis showed that subclinical hypothyroidism was not associated with atrial fibrillation (adjusted RR=1.20, 95%CI 0.92 to 1.57, P=0.18) and subclinical hyperthyroidism could increase the risk of atrial fibrillation (adjusted RR=1.65, 95%CI 1.12 to 2.43, P=0.01). Subgroup analysis showed that for the community population, subclinical hypothyroidism was not associated with atrial fibrillation (adjusted RR=1.03, 95%CI 0.84 to 1.26, P=0.81); for cardiac surgery, subclinical hypothyroidism could increase the risk of atrial fibrillation (adjusted RR=2.80, 95%CI 1.51 to 5.19, P=0.001); subclinical hyperthyroidism could increase the risk of atrial fibrillation among patients with TSH≤0.1 mlU/L (adjusted RR=2.06, 95%CI 1.07 to 3.99, P=0.03) and TSH=0.1～0.44 mlU/L (adjusted RR=1.29, 95%CI 1.01 to 1.64, P=0.04). ConclusionsSubclinical hypothyroidism is not associated with atrial fibrillation and subclinical hyperthyroidism can increase the risk of atrial fibrillation. Due to limited quantity and quality of included studies, more high quality studies are needed to verify above conclusions.