Assessment of cardiometabolic risk using single point insulin sensitivity estimator (SPISE) in pediatric Bardet-Biedl Syndrome: a pilot study.

Abstract

Background: Bardet-Biedl syndrome (BBS) carries early cardiometabolic risk, yet pediatric screening is complicated by growth and puberty. The metabolic syndrome (MetS) z-score provides a continuous benchmark for clustered risk. The single-point insulin sensitivity estimator (SPISE), based on body mass index (BMI) and fasting lipids, may offer a practical alternative where insulin testing is impractical. We aimed to assess the association between SPISE and cardiometabolic burden in children with molecularly confirmed BBS, and to compare its ability to identify MetS against the MetS z-score benchmark and insulin-derived indices.

Methods: Single-center retrospective pilot study including children/adolescents with genetically confirmed BBS who underwent standardized anthropometry and metabolic profiling (fasting lipids, glucose, insulin; OGTT when available). SPISE-MetS z-score associations were examined using Spearman and adjusted analyses. In adolescents (≥ 10 years), MetS discrimination was evaluated with ROC curves for SPISE, TG/HDL, and homeostatic model assessment for insulin resistance (HOMA-IR), with pairwise DeLong comparisons and Youden-optimal thresholds.

Results: Fourteen participants (7 females, 7 males) were evaluated. Median age at last visit was 11.7 years [IQR 7.6-15.5]; BMI SDS was 3.05 [2.47-3.57]. The median MetS z-score was 1.60 [0.90-1.75]. SPISE correlated inversely with the MetS z-score (ρ=-0.57, p = 0.021), and adjusted models (age, sex, BMI-SDS) retained significance. Among adolescents (n = 10), SPISE showed the highest AUC for MetS (AUC 0.95; 95% CI 0.82-1.00) versus TG/HDL (AUC 0.81) and HOMA-IR (AUC 0.60); pairwise differences were not statistically significant. Youden-optimal SPISE ≤ 3.34 identified MetS with high sensitivity in adolescents. Confidence intervals were wide, reflecting the small sample size.

Conclusions: In this single-center pediatric BBS cohort, SPISE tracked continuous MetS burden and showed numerically stronger discrimination for MetS than insulin-derived indices. These findings highlight the potential utility of SPISE as a feasible tool for cardiometabolic monitoring in syndromic obesity, where laboratory access may be limited. Beyond BBS, SPISE may support early risk stratification and follow-up in rare obesity models of metabolic risk, but multicenter prospective validation remains warranted.