Background although obesity is a risk factor for developing coronary artery disease1 and cardiovascular diseases account for approximately half of the deaths among rheumatoid arthritis (RA) patients2, anthropometric measures are not accurate for fat mass quantification in this population.3
Objectives to identify a serum biomarker of fat excess in patients with RA.
Methods cross-sectional study in adults with established RA. Disease activity was assessed by DAS28 and CDAI. Anthropometric measures included waist circumference (WC), weight and height for body mass index (BMI) calculation. Body composition by DXA (Hologic Discovery W, software 3.3.01) was used to fat mass excess quantification.4 Circulating levels of IL-6, TNF alpha, IL- 1β and leptin were measured in a single sample of peripheral blood using the technique of Bead-Based Multiplex Immunoassays- Luminex; while adiponectin was measured by Enzyme-Linked Immunosorbent Assay-ELISA.
Results 99 patients were included, 89.9% women, with mean age of 54.5 (±11) years and mean disease duration of 16.5 (±9.3) years. The frequency of obesity was 31.3% by BMI, 85.9% by WC and 57.6% by DXA. Mean serum leptin concentration was 24.5 (± 22.5) ng/ml. Leptin correlated with obesity by the three methods: BMI, WC and DXA. This correlation was stronger with DXA. The correlation between leptin and DXA was not influenced by DAS28, C-reactive protein, erythrocyte sedimentation rate, nor by inflammatory cytokines levels (IL -6, TNF-alpha, IL- 1β). Analysis by ROC curve determined the cut-off point of 6.52 ng/ml of leptin as obesity marker, with a sensitivity of 96.43% and a specificity of 23.81%.
Conclusions serum concentration of leptin presents as a fat mass excess biomarker, being useful since more accurate diagnostic methods for measuring fat mass are not available in clinical practice.
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Disclosure of Interest None declared