Validation of an enhanced pediatric vitamin D deficiency score incorporating sun exposure timing and BMI z-score: analysis in a combined cohort of children

Early identification of vitamin D (VitD) deficiency in childhood is essential to support timely prevention and intervention strategies. Building on the previously validated pediatric EVIDENCe-Q questionnaire, this study aimed to refine the tool by integrating two patient-specific weighted variables, sun exposure during peak UVB hours, and BMI z-score categories, both recognized determinants of circulating 25-hydroxyvitamin D (25-OH-D) levels. A total of 354 children (190F/164 M) completed a 20-item pediatric VitD risk questionnaire. Serum 25-OH-D concentrations were available for 280 participants. Three scoring algorithms were evaluated: the unweighted standard model, the sun-weighted model, and the sun + BMI-weighted model. Statistical analyses included ANOVA, Pearson correlations, and receiver operating characteristic (ROC) analyses across biochemical thresholds of vitamin D deficiency and insufficiency (< 10, < 20, and < 30 ng/mL). Vitamin D deficiency (< 10 ng/mL) was observed in 6.8% of participants, while insufficiency affected 38.1% (< 20 ng/mL) and 74.7% (< 30 ng/mL). The unweighted standard model did not discriminate among vitamin D categories (p = 0.622). In contrast, both weighted models showed significant discrimination (sun-weighted: p = 0.036; sun + BMI-weighted: p = 0.030). Only the sun + BMI-weighted model was significantly correlated with serum 25-OH-D levels (r = − 0.13; p = 0.023). ROC analyses demonstrated limited accuracy for the unweighted model, whereas the weighted models showed moderate discriminatory ability, with the Sun + BMI-Weighted Model providing the strongest overall performance. Conclusions: Incorporating weighted patient-specific variables improves the discriminatory capacity of the pediatric EVIDENCe-Q. Despite moderate accuracy, particularly at lower thresholds, the refined questionnaire, especially the sun + BMI-weighted version, represents a practical, noninvasive screening tool to identify children at risk of hypovitaminosis D. (Table presented.)