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Objective: To ascertain whether body mass index (BMI) cutoffs calculated according to age and pubertal stage are superior to BMI cutoffs calculated on the basis of age alone at correctly identifying children and adolescents with high levels of adiposity. Design: Cross-sectional study. Setting: Dunedin, a university city in New Zealand. Subjects and measurements: In total, 368 healthy Caucasian children and adolescents (179 males, 189 females) aged 8.5-15.5 y had their percentage body fat measured by dual-energy X-ray absorptiometry (DXA). High adiposity was defined as ⩾25% body fat in males and ⩾35% body fat in females. The sensitivity, specificity and areas under the receiver operating characteristic curves of two Z-score distributions of BMI were calculated for each gender. Results: Forty-nine males (27.3%) and 43 females (22.8%) had high DXA-measured percentage body fat. In all, 86% of males and females with high adiposity were correctly identified by BMI cutoffs calculated according to age alone, with 89% of males and 97% of females with low adiposity being correctly classified. Similar results were observed when BMI cutoffs utilising both age and stage of pubertal development were used; 90% of males and 88% of females with high adiposity and 92% of both males and females with low adiposity were correctly classified according to BMI. Conclusions: Categorisation of BMI according to both age and pubertal stage of development does not produce cutoffs that are superior to BMI cutoffs calculated on the basis of age alone at identifying children with high DXA-measured adiposity. Sponsorship: University of Otago and the Health Research Council, New Zealand. [ABSTRACT FROM AUTHOR]

Objective: To assess the validity of a short calcium food frequency questionnaire (FFQ) for use in young children.Design: Calcium intake from an estimated 4 d diet record (4DDR) was compared with the calcium intake from a 35 item FFQ specifically designed to assess habitual calcium intake and previously validated for adult women.Subjects: Forty-one girls and 26 boys aged 3-6 y recruited by advertisement for studies of nutrition and bone health.Results: Mean (s.d.) calcium intakes were 798 mg (271) and 942 mg (419) for the 4DDR and FFQ respectively, (r = 0.52). Mean difference (s.d. of difference) in calcium intake between the two methods was 144 mg (355), showing that the FFQ may estimate calcium intakes 565 mg below to 854 mg above diet record values. 84% of subjects when classified by the 4DDR fell into the same or adjacent quartiles when classified by the FFQ. Only two subjects were classified in extreme quartiles for the two methods. The FFQ correctly identified 68% of children with recorded intakes less than 800 mg.Conclusions: The short calcium FFQ tended to overestimate actual calcium intakes in young children, and would not be appropriate for determining calcium intake of individuals. However, the FFQ demonstrated good ability to classify subjects into extremes of calcium intake. Moreover, the predictive value of the FFQ in identifying children with intakes below the current recommended intake of 800 mg was reasonably high (79%). [ABSTRACT FROM AUTHOR]