The association between CALLY index and obesity in adolescents: a comparative analysis with traditional inflammatory...

To investigate the association between the C-reactive protein-Albumin-lymphocyte (CALLY) index and obesity in adolescents, and evaluate its predictive performance compared to traditional inflammatory markers.

Data from NHANES 2015-2018 were analyzed, including 2188 adolescents aged 12-20 years. The CALLY index was calculated as (albumin × lymphocytes)/CRP. Multivariate weighted logistic regression was used to assess associations with obesity. Receiver Operating Characteristic (ROC) curves and Area Under the Curve (AUC) were computed to evaluate the predictive performance of the CALLY index compared to traditional inflammatory markers (NLR, PLR, SII, SIRI). Survey-weighted logistic regression assessed associations of CALLY with obesity; model fit (Nagelkerke R²) and discrimination were evaluated, with sensitivity analyses for model specifications.

The CALLY index was inversely associated with obesity (OR = 0.968, 95% CI 0.958-0.977, p < 0.001), with each 1-unit increase reducing obesity odds by 3.20%. This association remained significant after multivariate adjustment and varied by age, race, and physical activity. The standalone AUC of CALLY (0.743) significantly outperformed traditional markers (PLR: 0.515, NLR: 0.546, SII: 0.593, SIRI: 0.598). Combined with covariates, AUC increased to 0.774 (DeLong test p < 0.001). At the cutoff of 15.10, CALLY achieved > 80% sensitivity with a positive likelihood ratio near 2.0.

The CALLY index is a robust and independent predictor of obesity in adolescents, outperforming traditional inflammatory markers. Its integration with traditional covariates further enhances predictive accuracy, suggesting that the CALLY index could be a valuable tool for early screening and intervention in adolescent obesity.