Meta-analysis on the Association Between Thyroid Hormone Disorders and Arterial Stiffness

CONTEXT: Aortic stiffness is an emerging predictor of cardiovascular morbidity and mortality. Current data about the effect of subclinical and overt thyroid hormone disorders on aortic stiffness are often conflicting. OBJECTIVE: Primary outcome was to investigate if subclinical and overt thyroid hormone disorders were associated with aortic stiffness. Secondary outcome was to identify disease effect modifiers. METHODS: Data sources were PubMed, Google Scholar, SCOPUS, Web of Sciences, and the Cochrane Library. Eligible studies included reports of pulse wave velocity (PWV), which is the gold standard method for measuring aortic stiffness, in patients with subclinical and overt thyroid disorders. Two investigators independently identified eligible studies and extracted data. Pooled mean difference was the summary effect measure. Data were presented in forest plots with outlier and influential case diagnostics. Univariate meta-regression analysis was used to identify effect modifiers. RESULTS: Eleven observational studies were selected, including 1239 patients with subclinical hypothyroidism, 81 patients with overt hypothyroidism, 338 patients with thyrotoxicosis, and 12 715 controls. PWV was significantly higher in subclinical (P < .001) and overt hypothyroidism (P < .001), as well as in patients with thyrotoxicosis (P = .027) compared with controls. Age was an effect modifier in hypothyroid patients. CONCLUSION: This study shows that both overt and subclinical hypothyroidism as well as thyrotoxicosis were associated with an increase of aortic stiffness. The impact of treatment of these conditions on aortic stiffness should be assessed in clinical trials.