ROC and CART analysis of subcutaneous adipose tissue topography (SAT-Top) in type-2 diabetic women and healthy females

Abstract

Women suffering from type-2 diabetes mellitus (NIDDM) show a more android fat pattern than healthy females, but to date no exact determination of their fat distribution differences exists. Measurements at 15 specified body sites with an optical device, the LIPOMETER, provide a subcutaneous adipose tissue topography (SAT-Top) of the individual. SAT-Top of 20 female NIDDM patients and 122 healthy controls was measured. ROC curve analysis was applied to evaluate the discriminative power of each body site and to provide cutoff values. Then a classification tree by the CART algorithm was established, showing SAT-Top differences between the two groups. Best discriminating results were achieved by the neck site (ROC area index = 0.76, sensitivity = 61.3%, specificity = 77.8%), the four sites of the thigh (area indices from 0.71 to 0.76), and a linear combination of all body sites stemming from a previous factor analysis, which provides condensed information of the extremities SAT-Top (area index = 0.80, sensitivity = 80.4%, specificity = 64.6%). The results could be improved by a summary measure of "android fat pattern" (area index = 0.89, sensitivity = 73.6%, specificity =88.3%) and a proportional measure of SAT-distribution, the relative neck (area index = 0.84, sensitivity = 83.0%, specificity = 70.5%). Overall, 136 (95.8%) of the 142 subjects were correctly classified by the classification tree (sensitivity = 75%, specificity = 99.2%). Both methods show the expected increased upper trunk obesity and decreased lower body obesity of NIDDM women compared with healthy females. Am. J. Hum. Biol. 12:388-394, 2000. Copyright 2000 Wiley-Liss, Inc.