Comparison of Body Mass Index and the Index of Adiposity in Patients with Juvenile Systemic Lupus Erythematosus

Abstract

Objective: Compare the ability of body adiposity index (BAI), body mass index (BMI) and abdominal and hip circumferences to estimate body fat composition using the percentage of body fat measured by dual energy X-ray absorptiometry (DXA) as gold standard in patients with Juvenile Systemic Lupus Erythematosus (jSLE). Methods: Sixty four patients with jSLE and 64 controls matched for sex and age were included. Anthropometric data, BMI and BAI were obtained for all subjects. Clinical and laboratory data of patients with jSLE, including disease activity index, cumulative damage, and current and cumulative dose of corticosteroids were assessed from medical records. Fat mass, lean mass and fat percentage were obtained by DXA in patients with jSLE. Results: There were increased abdominal-hip circumferences ratios in patients with jSLE when compared to controls (p !0.001). There was no difference in the classification of obesity by BMI and BAI in patients with jSLE and controls. Using DXA as gold standard method, it was observed that all indirect measures of body fat correlated with total fat mass. In total body analysis there was correlation between lean mass and damage index (r 5 -0395, p 5 0.019); fat percentage and activity of disease calculated over time (r 5 0.402, p 5 0.008) and with duration of disease (r 5 -0370, P 5 0.012). In trunk composition analysis, there was correlation between lean mass and damage index (r5 -0.319, p5 0.042); fat percentage and calculated disease activity calculated over time (r 5 0.402, p 5 0.005), and also with the duration of disease (r 5 -0.408, p 5 0.005). Conclusion: Indirect estimations of body fat and clinical parameters correlated moderately with total body fat assessed by DXA. This study shows that there is no need to replace the BMI by BAI in the evaluation of body fat in jSLE. Considering the importance of obesity in cardiovascular disease genesis, it is recommended to use both anthropometric indexes and DXA in order to improve the prognosis of patients with jSLE.