Estudo da obesidade em pacientes com artrite reumatoide definida por índices antropométricos e pela avaliação densitométrica da composição corporal

Abstract

Introduction: Rheumatoid arthritis (RA) is an independent risk factor for cardiovascular disease (CVD). Obesity and systemic inflammation may be contributing factors to increase cardiovascular risk in this population. The systemic inflammatory process of RA can modify the relationship between body fat and lean mass and standard anthropometric measures used to diagnose obesity in the general population may not have the same performance in these patients. Objectives: To establish the relationship between circulating levels of inflammatory cytokines and adipokines and obesity in people with RA defined by anthropometric measures and by X-ray absorptiometry dual energy absorptiometry (DXA). To identify an obesity biomarker in patients with RA. To determine cut-off points for body mass index (BMI) and waist circumference (WC) for detecting obesity in women with RA by comparing these standard measures to a dual-energy x-ray absorptiometry (DXA)-based obesity criterion. Methods: Cross-sectional observational study in RA patients, consecutively included among individuals followed at the Rheumatology Service of the Hospital das Clínicas da UFMG . Disease activity was assessed by clinical and laboratory examination with calculation of DAS28 and CDAI. The measurement of WC and the BMI calculation was performed on the same day of body composition by DXA ( Hologic , Discovery W model). Circulating levels of IL-6, TNF , IL- 1 , leptin and adiponectin were measured in a single sample of peripheral blood. Results: Ninety-nine patients were included , mean age 54 ± 11.1 years , 89 ( 89.9 %) female patients . The diagnosis of obesity in the sample was 31.3 % by BMI , 85.9 % by WC and 57.6 % by DXA . Cut-off points were identified for anthropometric measures to better aproximate DXA estimates of percent body fat : BMI value 25 kg/m² was the best for definition of obesity in female patients with RA, with sensitivity of 80 % and specificity of 60%. For WC, with 80 % of sensitivity and 35 % of specificity , the best value to detect obesity was 86 cm. Leptin correlated with obesity by the three methods: BMI , waist circumference and DXA . This correlation was stronger with DXA, which is the gold standard . The cutoff point of 6.52 ng / ml of leptin was defined as obesity marker in this population. Conclusions: The traditional cut-off points used for obesity were not suitable for our sample. For this female RA population, BMI cut-off point of 25 kg/m² and WC cut-off point of 86 cm were