Obesity is an independent contributor to functional capacity and inflammation in systemic lupus erythematosus

OBJECTIVE: Obesity induces a proinflammatory state and is a major cause of morbidity in the general population. However, little is known about the effects of obesity in patients with chronic inflammatory illnesses such as systemic lupus erythematosus (SLE). METHODS: One hundred consecutive patients with SLE were studied to determine the relationship between body mass index (BMI) and functional capacity, measures of fatigue, quality of life, and the inflammation markers C-reactive protein (CRP), the erythrocyte sedimentation rate, and interleukin-6 (IL-6). The association between BMI and patient characteristics was determined, and multiple logistic regression models were used to adjust for age, sex, disease activity, and disease-related damage. RESULTS: Thirty-three patients had a normal BMI (< 25 kg/m(2)), 28 were overweight (25-29.9 kg/m(2)), and 39 were obese (> or =30 kg/m(2)). Obese patients had worse functional capacity, more fatigue, and higher concentrations of inflammation markers. The mean +/- SD modified Health Assessment Questionnaire (M-HAQ) score was 0.6 +/- 0.4 in obese patients compared with 0.3 +/- 0.4 and 0.2 +/- 0.3 in overweight patients and those with a normal BMI, respectively (P = 0.001). The mean +/- SD concentrations of CRP in obese patients (10.0 +/- 8.6 mg/liter) were higher than those in patients who were overweight (4.7 +/- 5.4 mg/liter) or had a normal BMI (6.2 +/- 9.9 mg/liter) (P < 0.001). Similarly, concentrations of IL-6 were higher in obese patients (P = 0.003). After adjusting for age, sex, disease activity, and damage indices, the associations between BMI and CRP (P < 0.001), M-HAQ scores (P = 0.005), and IL-6 concentrations (P = 0.01) remained significant. CONCLUSION: Obesity is independently associated with impaired functional capacity and inflammation markers in patients with lupus. Thus, weight loss may improve functional capacity and decrease cardiovascular risk factors.