Metabolic syndrome severity score is associated with diastolic dysfunction and low-grade inflammation in a community-based cohort

Metabolic syndrome (MetS) affects approximately one out of three adults in western countries and it combines a cluster of cardiovascular risk factors. A continuous gender and race/ethnicity-specific MetS severity score was recently described and validated, and is an independent predictor of cardiovascular events, beyond individual MetS components. We aimed to assess if this score was associated with subclinical diastolic dysfunction. Additionally, we searched for a potential relationship between MetS severity score and inflammatory/insulin-resistance markers. This was a cross-sectional study of a communitybased cohort consisting of 925 adults, aged 45 years or older, without any known cardiovascular disease. A detailed description of the cohort assembly is provided elsewhere. All participants underwent clinical, analytical (insulin, adiponectin, leptin and high-sensitivity C-reactive protein (hs-CRP)) and echocardiographic examination (including e’ velocities and E/e’ ratio). Insulin resistance was estimated according to the homeostatic model assessment (HOMA), as the product of fasting glucose (in milligrams per decilitre) and insulin (in milliunits per litre) divided by a constant of 405. MetS was defined using the 2005 American Heart Association/National Heart, Lung, and Blood Institute criteria (MetS criteria showing the strongest association with cardiovascular disease in the Portuguese population). A continuous MetS severity z-score was applied to all patients, in theory normally distributed and ranging from theoretical negative to positive infinity with mean1⁄4 0 and standard deviation1⁄4 1. We used two of the six equations, as described by Gurka et al.: a) non-Hispanic white males: score1⁄4 5.4559þ 0.0125 waist circumference 0.0251 high-density lipoprotein cholesterol (HDL-C)þ 0.0047 systolic blood pressure (SBP)þ 0.8244 ln(triglycerides)þ 0.0106 glucose; b) non-Hispanic white females: score1⁄4 7.2591þ 0.0254 waist circumference 0.0120 HDL-Cþ 0.0075 SBPþ 0.5800 ln(triglycerides)þ 0.0203 glucose. Diastolic dysfunction was defined using three criteria: 2009 and 2016 European Association of Cardiovascular Imaging/American Association of Echocardiography (EACVI/ASE) recommendations and a 2017 clinically oriented algorithm. Regarding the statistical analyses, continuous variables are reported as mean standard deviation or median (interquartile range), according to normality of distribution. Discrete variables are described using frequency and percentage. The HOMA index, hs-CRP, adiponectin and leptin were included in the analyses as a base-2 logarithm due to their skewed distribution (normality was assessed using the Kolmogorov– Smirnov test). One unit variation of the base-2 logarithmic transformation would be equivalent to a doubling of the variable of interest. Bivariate correlations were assessed by Pearson’s (r) correlation coefficient (nonnormally distributed variables were previously logarithmically transformed). Independent t-test was used to compare MetS severity score in individuals with normal diastolic function and individuals with diastolic dysfunction. Multivariable linear regression analysis