Leptin as a predictor of metabolic syndrome in prepubertal children

Abstract

Objective: Leptin has been suggested as a potential biomarker of cardiovascular risk. This paper aims to ascertain, based on a sample of prepubertal children, which serum leptin value best suited to identify metabolic syndrome (MS).

Subjects and methods: This observational, cross-sectional study recruited children from the outpatient pediatrics clinic, with the purpose of validating serum leptin level cutoffs to identify MS. All obese and overweight children who met eligibility criteria were included in the study, as was a sample of normal-weight children. The sample underwent clinical assessment and blood fasting glucose, lipid profile, insulin, and leptin were measured. Sensitivity and specificity were estimated for each leptin measurement, using MS as the outcome. These values were used to construct a receiver operating characteristic (ROC) curve. The association between MS and leptin was assessed using logistic models to predict MS.

Results: A total of 65 normal weight, 46 overweight, and 164 obese children were analyzed (160 boys, 115 girls; age: 93.7 ± 17.8 months). The most appropriate leptin cutoff was 13.4 ng/mL (sensitivity 67.6%; specificity 68.9%; accuracy 72.1%). The logistic model indicated that leptin levels above 13.4 ng/dL were significantly associated with MS and that, for every 1 ng/dL increase in leptin levels, the odds of MS increase by 3% (p = 0.002; OR 1.03; 95% CI 1.01-1.05).

Conclusions: Leptin may be a useful biomarker of cardiovascular risk in prepubertal children, with an optimal cutoff of 13.4 ng/mL. Identification of potential new risk markers for cardiovascular disease in children could contribute to the development of preventive strategies.

Figure 1. ROC curves of logistic regression prediction models for metabolic syndrome (response variable) in relation to the main predictor (leptin level), based on observations of prepubertal children. (A) Crude model: best cutoff point, 12.3 ng/mL; area under the curve, 76.4%; Youden’s index, 48.8%. (B) Model adjusted for sex and age: best cutoff point, 13.4 ng/mL; area under the curve, 72.1%; Youden’s index, 36.5%. On both charts, the best cutoff is denoted by the intersection of the dotted lines. The area under the curve represents the overall accuracy of the test.

Figure 2. Odds of metabolic syndrome stratified by leptin levels (ng/mL). (A) Crude logistic model: odds ratio (95%CI) = 1.04 (1.01-1.06); p < 0.002; equation for the odds of metabolic syndrome = exp (- 2.51 + 0.03 * leptin). (B) Model adjusted for sex and age: odds ratio (95%CI) = 1.03 (1.01-1.06); p < 0.002; equation for the odds of metabolic syndrome = exp (-5.19 + 0.03 * leptin – 0,32 * sex + 0.03 * age in months).