Visceral body fat risk factor for all-cause, obesity-related mortality
MedWire News: Visceral body fat (VF) is associated with all-cause and obesity-related mortality in Japanese Americans, independent of waist circumference, study results show.
However, in terms of predictive power, VF did not significantly improve mortality risk assessment beyond that of body mass index (BMI), note study co-author Marguerite McNeely (University of Washington, Seattle, USA) and colleagues in the journal Diabetes Care.
To date, only one study of 291 men, followed for 2 years, has examined the association between VF and mortality.
The researchers therefore analyzed data from the Japanese Community Diabetes Study, involving 733 Japanese Americans aged 34-74 years who were followed up for an average of 16.9 years.
Most participants attended three or more follow-up visits where data were obtained for smoking habits, medical history, waist circumference at the umbilicus, height, weight, and fasting plasma insulin and glucose levels.
VF and subcutaneous abdominal fat were measured using a single-slice 10 mm computed tomography scan at the level of the umbilicus.
In total, 161 participants died by the end of the study period. Of these, 54 died after age 82 years, leaving 107 deaths for analysis. There were 68 obesity-related deaths, 46 of which were from cardiovascular disease.
Mortality risk was analyzed using time-dependent Cox proportional hazard models. Hazard ratios (HRs) were estimated as the risk associated with an increase equivalent to the magnitude of the interquartile range (25th to 75th percentile).
McNeely et al found that a higher VF was significantly associated with all-cause mortality (HR=1.39) and obesity-related mortality (HR=1.39).
After further adjustment for waist circumference, VF remained significantly associated with all-cause mortality (HR=1.41) but not with obesity-related mortality.
The associations between mortality and VF were not, however, independent of BMI. Furthermore, the relationship was attenuated by adjustment for fasting glucose or fasting insulin, say McNeely and team, suggesting that glycemia or insulinemia may partially mediate this association.
The researchers conclude: "We cannot exclude the possibility that VF may be associated with mortality independently of BMI in larger studies."
MedWire (http://www.medwire-news.md/) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012
By Andrew Czyzewski