Rationale/Background: Beyond overall obesity, VAT storage is associated with adverse metabolic parameters that increase the risk of heart disease, stroke, and type II diabetes. Computed tomography (CT) and magnetic resonance imaging (MRI) technologies have been used to define thresholds of VAT associated with MetS, however these techniques are of limited availability for clinical risk assessment. Dual energy X-ray absorptiometry (DXA) is accurate compared to VAT measures from CT and MRI, however differences in scanning region and algorithms results in device-specific VAT estimates. We recently generated cross-calibration equations for DXA systems, allowing DXA measures to be compared to CT and MRI and providing more access to VAT assessments for the determination of VAT thresholds as well as the ability to assess presence of “risky” VAT levels in clinical practice. The purpose of this review was to identify published studies defining VAT thresholds to determine characteristics that define the “risky” threshold.
Methods: We identified previously published studies establishing VAT thresholds associated with increased cardiometabolic risk, obtained using CT, MRI, and DXA imaging technologies. We compared characteristics of these studies to determine the factors necessary to identify “risky” VAT thresholds.
Results: We identified 46 studies that derived VAT-specific thresholds associated with MetS in adults, published across populations with diverse sample size, age, and ethnicity. Lower average VAT as well as risk thresholds were found in females. When stratified by age or menopausal status, lower VAT thresholds were primarily observed in lower age or premenopausal categories. Values varied across ethnicities, with level thresholds often lower in Asian populations (70-136 cm2) compared to Caucasian (85.6-165.9 cm2) and other populations. A universal VAT threshold is not yet feasible, supporting the need for more population-specific thresholds to identify increased MetS risk.
Implications: Excess VAT accumulation above a certain threshold is strongly linked to MetS risk, however the need for age-, sex- and ethnic-specific thresholds in necessary. The development of thresholds based on sex is necessary to reduce the risk of underestimation of “risky” VAT in females. Additionally, these findings suggest that different adipose tissue regions may have differential effects on metabolic disease risk among race/ethnic groups.
Contributing Author: Michael Wong, PhD – University of Hawaii Cancer Center Contributing Author: Carla Prado, PhD – University of Alberta Contributing Author: Steven Heymsfield, MD – Pennington Biomedical Research Contributing Author: John A. Shepherd, PhD – Professor, University of Hawaii Cancer Center
