Abstract
Background/ObjectivesIndividuals with HIV are susceptible to visceral fat accumulation, which confers an increased risk of cardiometabolic disease. Advanced software to ascertain visceral fat content from dual-energy X-ray absorptiometry (DXA) has not been validated among this population. We sought to compare DXA with computed tomography (CT) in the measurement of visceral fat cross-sectional area (VAT) in HIV and non-HIV using Bland–Altman analyses.Subjects/MethodsData were combined from five previously conducted studies of individuals with HIV (n = 313) and controls without HIV (n = 144) in which paired DXA and CT scans were available. In cross-sectional analyses, DXA-VAT was compared with CT-VAT among participants with and without HIV. In longitudinal analyses, changes in VAT over time were compared between DXA and CT among participants with and without HIV receiving no intervention over 12 months and among individuals with HIV receiving tesamorelin—a medication known to reduce VAT—over 6 months.ResultsIn HIV, DXA underestimated VAT compared with CT among individuals with increased visceral adiposity. The measurement bias was −9 ± 47 cm2 overall, but became progressively larger with greater VAT (P < 0.0001), e.g., −61 ± 58 cm2 among those with VAT ≥ 200 cm2. Sex-stratified analyses revealed that the relationship between VAT and measurement bias was especially pronounced in men (P < 0.0001). Longitudinally, DXA underestimated changes in VAT, particularly among those at the extremes of VAT gain or loss (P < 0.0001). In contrast to the cross-sectional findings, the tendency for DXA to underestimate longitudinal changes in VAT was evident in both men and women. Analogous findings were seen among controls in cross-sectional and longitudinal analyses.ConclusionsDXA underestimated VAT relative to CT in men with and without HIV, who had increased visceral adiposity. DXA also underestimated changes in VAT over time in men and women, irrespective of HIV status. DXA-VAT should be used with caution among both HIV and non-HIV-infected populations.
Highlights
Independent of body mass index (BMI), fat distribution is an important determinant of cardiometabolic health[1]
In HIV, dual-energy X-ray absorptiometry (DXA) underestimated visceral fat cross-sectional area (VAT) compared with computed tomography (CT) among individuals with increased visceral adiposity
In contrast to the cross-sectional findings, the tendency for DXA to underestimate longitudinal changes in VAT was evident in both men and women
Summary
Independent of body mass index (BMI), fat distribution is an important determinant of cardiometabolic health[1]. Consonant with findings from the general population, HIV-related changes in fat distribution have been shown to confer an increased risk of cardiovascular disease[10–12]. In HIV and in the general population, there is a critical need for a safe, affordable, and accurate method to quantify visceral fat. Such an approach would allow for the routine clinical use of visceral fat measurement to stratify cardiovascular risk and to monitor the efficacy of metabolic interventions. The gold standard for abdominal adipose tissue measurement is computed tomography (CT)[13] In this regard, visceral fat cross-sectional area at the L4 vertebral level (CT-VAT) has been widely adopted due to its strict relation to skeletal landmarks and high degree of reproducibility (r = 0.99)[13,14]. As CT involves radiation exposure and is costly, alternative means to assess visceral fat have been sought[15]
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