Comparison Of Trunk/Legs To Trunk/Total Dual-Energy X-Ray Absorptiometric Indexes Of Abdominal Obesity In Differentiation Of Cushing’s And Obese Women

Abstract

Objectives: Patients with Cushing’s syndrome (CS) are obese or overweight, and have abdominal, visceral adiposity. Accurate quantitative assessment of the visceral adiposity is essential in the evaluation of potential risk for the development of serious medical illnesses. Dual-energy X-ray absorptiometry (DXA) method is the gold standard for assessment of bone health and body composition that provides accurate, comprehensive, precise measurements of total and regional body fat distribution. Determination of DXA indexes cut-off point values of abdominal obesity is very important to discover obese women with abdominal obesity. Material and Methods: DXA assessment of body composition and body fat distribution was performed in two groups of women, each consisting of 21 subjects: 1st group of Cushing’s syndrome with clinically confirmed CS with Body Mass Index (BMI) (30.03±6.49 kg/m2) and age of 42.98±13.27 years and 2nd group of obese women (O), matched with CS according to their BMI (29.91±6.12 kg/m2) and age (41.04±12.85 years). Trunk tissue mass (Tr-T) and trunk fat mass (Tr-F) and their percentages values, trunk tissue percent fat (Tr-T%f) and trunk fat percent (Tr-F%) were determined. Legs and total tissue mass (L-T; To-T) and legs and total fat mass (L-F; To-F) and their percentages (L-T%f; To-T%f) and (L-F%; To-F%) were determined also. Their ratios Tr/L-T and Tr/To-T, Tr/L-F and Tr/To-F, Tr/L-T%f and Tr/To-T%f, Tr/L-F% and Tr/To-F % were determined as indexes of central, abdominal obesity and their cut-off point values that best differentiate CS women from O were determined. Sensitivity (S), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and DG (diagnostic accuracy) of these idexes were determined. Results: Tr/L-T and Tr/To-T values in CS were significantly higher compared to O as well as Tr/L-F and Tr/To-F values in CS were also significantly higher compared to O (p<0.0001). Tr/L-T%f and Tr/To-T%f values in CS as well as Tr/L-F% and Tr/To-F% values in CS were significantly higher compared to O (p<0.0001). Tr/To-T cut-off point value of 0.52 and Tr/L-T cut-off point value of 1.6 best differentiated CS from O for DG of 88.89%. Tr/To-F cut-off point value of 0.53 and Tr/L-F of 1.8 best differentiated CS from O for DG of 83.33% and 88.89%. Tr/To-T%F and Tr/L-T%f best differentiated CS from O for DG of 69.44% and 72.22% respectively. Tr/To-F% and Tr/L-F% best differentiated CS from O for DG of 72.22% and 77.78%. Tr/To-T, Tr/L-T, Tr/T-F and Tr/L-F differentiated CS and O with higher diagnostic accuracy compared to their percentage values. Conclusion: All examined indexes confirmed abdominal, visceral obesity in CS with significantly higher values in CS compared to matched obese women. Tr/To-T and Tr/L-T as well as Tr/To-F and Tr/L-F indexes differentiated CS from obese women with very similar diagnostic accuracy. Percentage ratios of the DXA indexes differentiated the two examined groups with lower diagnostic accuracy and are not useful in diagnosing the abdominal obesity.