Association of novel hybrid and traditional anthropometric indices with kidney function among adolescent girls in Northeast Iran

The relationship between novel composite adiposity indices (Visceral Adiposity Index [VAI] and Lipid Accumulation Product [LAP]) and traditional anthropometric measures (body mass index [BMI] and waist-to-height ratio [WHtR]) with kidney function in adolescents remains unclear. This study investigated the associations of these four indices with kidney function in adolescent girls. In this cross-sectional study, 802 adolescent girls were recruited from northeastern Iran. Estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m 2 defined reduced eGFR. Logistic regression and covariate-adjusted ROC analysis were used to assess the associations and discriminatory ability of VAI, LAP, BMI, and WHtR. Non-linear associations were assessed by including quadratic and cubic terms in the adjusted models. BMI showed the highest discriminatory ability (AUC = 0.718, 95% CI 0.668–0.769), followed by LAP (AUC = 0.704, 95% CI 0.654–0.755), WHtR (AUC = 0.697, 95% CI 0.645–0.749), and VAI (AUC = 0.689, 95% CI 0.636–0.741). BMI, LAP, and WHtR were significantly associated with reduced eGFR in adjusted models, whereas VAI was not (OR = 1.448, 95% CI 0.956–2.194, p = 0.081). Consequently, no clinically valid cut-off was reported for VAI. These models revealed a significant linear association for BMI, WHtR, and VAI, whereas LAP showed a non-linear pattern (quadratic p = 0.009, cubic p = 0.027). All indices had limited explanatory power (adjusted R 2 ≤ 23.2%). BMI and WHtR, as simple and widely available anthropometric measures, were the most useful indices for identifying reduced eGFR, albeit with modest discriminatory ability. VAI was not independently associated with reduced eGFR and lacked a clinically valid cut-off, limiting its utility. The non-linear relationship for LAP warrants further investigation. Longitudinal studies are needed to refine risk assessment in this population.