Indices of central and peripheral body fat: association with non-fatal acute myocardial infarction

Abstract

The majority of the studies have focused on the effect of general and central fat on coronary risk, neglecting the potential role of peripheral body fat. To assess the effect of surrogate measures for general, central and peripheral body fat on the occurrence of non-fatal acute myocardial infarction (AMI). Population-based case-control study; cases were patients aged >or=40 years consecutively hospitalized with an incident AMI (n=653), and controls were community participants without previous AMI, selected randomly from the hospitals' catchment area population (n=1713). Body mass index (BMI), waist circumference (WC), hip circumference and a skinfolds composite index to estimate the proportion of peripheral subcutaneous fat in the arms were ascertained. Associations were summarized with odds ratios (OR) and 95% confidence intervals (95% CI), obtained from unconditional logistic regression with adjustment for the main confounders. WC, and in particular waist-to-hip ratio (WHR), had strong direct associations with AMI risk. Peripheral subcutaneous fat was inversely associated with AMI in women, but directly in men. Using principal component analysis, three uncorrelated factors were identified representing different patterns of fat distribution: (1) generalized fat, with high BMI and high WC; (2) central fat, with high WC and WHR; and (3) peripheral subcutaneous fat. The first factor showed no significant association with AMI, but the second factor increased AMI risk in each sex (upper vs lower fourth: OR 12.2, 95% CI 5.34-27.9 in women; OR 25.0, 95% CI 14.0-44.7 in men). In contrast, the third factor was inversely associated with AMI in women (upper vs lower fourth: OR 0.59, 95% CI 0.36-0.96) and directly associated in men (OR 2.45, 95% CI 1.69-3.55; P-value for sex interaction<0.001). Central fat was associated with increased risk of AMI in women and men, while the peripheral subcutaneous fat index predicted a lower risk of AMI in women and a higher risk in men.