Background Patients with systemic lupus erythematosus (SLE) have a higher incidence of metabolic syndrome (MetS). Among the possible causes we may mention the inflammation associated with increased levels of triglycerides and cytokines such as tumor necrosis factor alpha (TNF-α), in addition to other factors that may cause the increase of cholesterol and its LDL fraction. These factors contribute to the development of premature coronary artery disease.
Objectives To analyze the association of MetS and TNF-α serum levels in childhood-onset (c)SLE patients according to age-adjusted criteria
Methods We screened consecutive cSLE patients followed in a cohort at the pediatric rheumatology unit at the State University of Campinas. All patients had disease-onset before the age of 16. Controls were matched for age, sex and demographic background. cSLE patients were assessed for disease activity [SLE Disease Activity Index (SLEDAI)], damage [Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI)] both at study entry and over time. Total dose of prednisone was calculated in prednisone equivalent during the entire follow-up period. MetS was assessed using the definitions recommended by The National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEPIII) definition adjusted according to age. Obesity was defined as Body Mass Index (BMI) >30kg/m2. We determined height, weight, waist circumference (WC) and hip circumference (HC), measurements and fractions of cholesterol and fasting glucose levels for each individual. TNF-α levels were measured by ELISA.
Results We included 51 cSLE patients (47 women, mean age 17.6 years (SD±3.7; range) and 51 controls (47 females, mean age 18.2 years (SD±6.4; range). Disease duration was 12.47 years (SD±2.86; range 6-16 years). Thirty-seven (18.8%) patients were above the recommended average WC/HC, compared to 14 (7.14%) controls (p=0.03). MetS was identified in 9 cSLE and 1 control (p=0.01). The mean serum TNF-α level was 4.47±8.95pg/ml in cSLE, compared to 1.83±1.82pg/ml in healthy controls (p=0.004). We observed higher TNF-α levels in patients with obesity (p=0.036). No association between MetS criteria and serum TNF-α levels was observed. We observed a significant correlation between adjusted SLEDAI scores over time and the prevalence of MetS (r=0.68; p=0.01). In addition, TNF-α (p=0.001) levels were significantly increased in patients with active disease (SLEDAI≥3) and TNF-α levels correlated directly with SLEDAI scores (r=0.4; p=0.002). No correlation between cumulative corticosteroid dose, SDI scores and other clinical manifestations and prevalence of MetS was observed.
Conclusions cSLE patients have a higher prevalence of MetS than the general population. TNF-α levels were increased in cSLE patients with obesity. Disease activity over time was the only disease characteristics associated with MetS. The higher risk of coronary disease and atherosclerosis makes the evaluation of MetS imperative in cSLE patients.
Disclosure of Interest N. Sinicato Grant/Research support from: FAPESP 2010/13637-9, M. Postal Grant/Research support from: FAPESP 2009/10744-1, F. Peres Grant/Research support from: FAPESP 2010/10523-2, K. Peliçari Grant/Research support from: FAPESP 2010/13636-2, R. Marini: None Declared, S. Appenzeller Grant/Research support from: FAPESP 2008/02917-0; Conselho Nacional Pesquisa Desenvolvimento-Brasil CNPq (300447/2009-4)