Non-invasive markers of cardiovascular risk in patients with subclinical hypothyroidism: A systematic review and meta-analysis of 27 case control studies

Abstract

It has been reported that subclinical hypothyroidism (SCH) is closely related to subclinical atherosclerosis. According to the impact of SCH on noninvasive markers of cardiovascular risk, we fulfilled a meta-analysis of included studies to provide an integrated overview. We searched electronic databases and included all relevant studies involving SCH and epicardial adipose tissue (EAT), carotid intima-media thickness (CIMT), pulse wave velocity (PWV), flow-mediated dilation (FMD) and glyceryl trinitrate-induced dilation (GNT- induced dilation). The result was calculated in a meta-analysis to assess the impact of SCH on these markers. A total of 27 studies were entered in the final analysis. Compared with euthyroid subjects, SCH patients exhibited a significantly increased CIMT (SMD: 0.369 mm; 95%CI: 0.038, 0.700; P = 0.029) and EAT (SMD: 1.167 mm; 95%CI: 0.869, 1.466; P = 0.000) and increased PWV (SMD: 3.574 m/s; 95%CI: 0.935, 6.213, P = 0.008). We also found significantly lower FMD (SMD: −1.525%, 95%CI: −2.156, −0.894, P = 0.000) and lower GNT-induced dilation (SMD: −0.384%, 95%CI: −0.625, −0.142, P = 0.002). Sensitivity analysis and subgroup analysis confirmed the above results. Our meta-analysis confirmed a significant association of SCH and cardiovascular risk with arterial wall thickening and stiffening and endothelial dysfunction. These findings will help to establish detailed cardiovascular prevention strategies for SCH patients.

Hypothyroidism and related diseases: a methodological quality assessment of meta-analysis

“…Among the 52 included eligible MAs, 4628–73 (46/52, 88.5%) were published in English, and the rest74–79 (6/52, 11.5%) were published in Chinese. The 52 included MAs contained 685 studies, with an average of 13.2 (range: 3–39) studies per article.…”

“…Ten39 40 43 49 57 58 65 68–70 MAs were about the associations between OH and other diseases, and 3528–36 38 42 44–47 50–56 59–64 66 67 75–79 MAs have shown the associations between SCH and other diseases. Seven37 41 48 71–74MAs have investigated the effects of both OH and SCH on other diseases.…”

“…Items 7 and 8 recommend the assessment of the scientific quality of the original articles and consideration of the scientific quality when formulating conclusions, which should be based on scientific and cautious research results to provide an objective and reasonable suggestion for clinical professionals and stakeholders. Nineteen (36.5%)31 33 36 37 39 44 50 53 56 57 59 61 62 70–72 77–79 MAs did not assess the scientific quality of the included studies, which might decrease the credibility of the conclusions.…”

“…For the association between SCH and other diseases, four MAs36 59 66 75 reported that SCH was associated with a significant increase in carotid intima-media thickness. These MAs have an average of 2420 patients, and an average AMSTAR score of 8.75.…”

Endothelial dysfunction and the risk of atherosclerosis in overt and subclinical hypothyroidism

“…confirmed the significant association between SCH and cardiovascular risk with arterial wall thickening and stiffening and endothelial dysfunction. They suggested that these findings could help to establish cardiovascular prevention strategies for SCH patients ( 21 ). Our study results are consistent with that meta-analysis, and also proved the significant negative correlation between CIMT and endothelial function in both overt and subclinical hypothyroidism.…”