Validation of a composite diet quality index for U.S. adolescents

We validated The Revised Children’s Diet Quality Index (RC‐DQI) using dietary, anthropometric, and medical data of a nationally representative sample of 12–18 year olds (n=3,965) from NHANES 1999–2002. Z‐scores for CDC’s BMI‐for‐age growth charts were calculated to classify children as at risk for overweight (85–94 th %tile) or overweight (≥95 th %tile). Adolescent’s average score was 45 points (range 0–82 points) of the maximum 90 RC‐DQI points. Few met the dietary intake recommendations for dairy or whole grains (10% and 4% respectively). Non‐parametric test for trend indicated that with increasing RC‐DQI score quartiles HDL levels significantly increased while LDL decreased (z‐scores 2.81 and −2.74, p‐value<0.01, respectively). Also, the proportion of children with high body weight status significantly decreased with increasing RC‐DQI quartiles score (adolescents at risk for overweight decreased from 40% in the lowest RC‐DQI quartiles to 26% in the highest quartile while the proportion of overweight decreased from 23% to 12%). Our results indicate that the RC‐DQI is a valid total diet quality assessment tool in U.S. adolescents. However, this tool was developed to analyze group dietary intake levels and can not be employed to determine individual’s diet quality. This study was supported by USDA RIDGE Grant #K981834‐21 and a Seed grant of the College of Health and Human Development.