Conventional analyses of data from dietary validation studies may misestimate reporting accuracy: illustration from a study of the effect of interview modality on children's reporting accuracy.

OBJECTIVE: To compare two approaches to analysing energy- and nutrient-converted data from dietary validation (and relative validation) studies - conventional analyses, in which the accuracy of reported items is not ascertained, and reporting-error-sensitive analyses, in which reported items are classified as matches (items actually eaten) or intrusions (items not actually eaten), and reported amounts are classified as corresponding or overreported. DESIGN: Subjects were observed eating school breakfast and lunch, and interviewed that evening about that day's intake. For conventional analyses, reference and reported information were converted to energy and macronutrients; then t-tests, correlation coefficients and report rates (reported/reference) were calculated. For reporting error-sensitive analyses, reported items were classified as matches or intrusions, reported amounts were classified as corresponding or overreported, and correspondence rates (corresponding amount/reference amount) and inflation ratios (overreported amount/reference amount) were calculated. SUBJECTS: Sixty-nine fourth-grade children (35 girls) from 10 elementary schools in Georgia (USA). RESULTS: For energy and each macronutrient, conventional analyses found that reported amounts were significantly less than reference amounts (every P < 0.021; paired t-tests); correlations between reported and reference amounts exceeded 0.52 (every P < 0.001); and median report rates ranged from 76% to 95%. Analyses sensitive to reporting errors found median correspondence rates between 67% and 79%, and that median inflation ratios, which ranged from 7% to 17%, differed significantly from 0 (every P < 0.0001; sign tests). CONCLUSIONS: Conventional analyses of energy and nutrient data from dietary reporting validation (and relative validation) studies may overestimate accuracy and mask the complexity of dietary reporting error.

A 4-day sodium-controlled diet reduces variability of overnight sodium excretion in free-living normotensive adolescents.

The present analysis examined changes in the variability of overnight sodium excretion in 84 free-living adolescents (ages 15 to 19 years) on a 4-day sodium-controlled diet in which foods provided were selected by adolescents from an extensive list of menu items. The only selection criterion imposed was that foods selected for each day contain 4,000+/-200 mg sodium. Adolescents collected overnight urine samples. Repeated measures analysis of variance tested the effect of diet day on overnight sodium excretion, overnight urinary sodium concentration, and overnight urinary volume. Variance ratio test evaluated changes in overnight sodium excretion variance across days. Day 4 overnight sodium excretion was statistically lower than days 1 to 3 (1.84 vs 6.54, 5.94, and 5.52 mEq/h [1.84 vs 6.54, 5.94, and 5.52 mmol/h]). Day 4 overnight urinary sodium concentration was lower than days 1 to 3 (32.16 vs 119.64, 109.61, and 111.32 mEq/L [32.16 vs 119.64, 109.61, and 111.32 mmol/L]). The variance of overnight sodium excretion from day 1 to day 4 was reduced 10-fold from 20.1 mEq/h (20.1 mmol/h) to 1.90 mEq/h (1.90 mmol/h). Daily overnight urine volumes remained constant, averaging 451.7 mL/day. The dietary protocol successfully reduced the variability of sodium intake as estimated by overnight sodium excretion in free-living adolescents. The protocol could be expanded to include baseline values, additional days of sodium control, and varying levels of dietary sodium intake.

Prevalence of cardiovascular risk factors in schoolchildren in a rural Georgia community.

BACKGROUND: In the context of a national childhood obesity epidemic, this study sought to document the cardiovascular risk status of children in a rural Georgia community. METHODS: Anthropometrics and blood pressure were measured in 211 children, and fasting glucose and lipid profile in 160, recruited from schools in 2002 (grades 2 to 11, ages 7 to 18 years). RESULTS: Nearly half the schoolchildren (48%) were overweight or at risk of overweight; 15% had metabolic syndrome. Overweight children were at higher risk for metabolic syndrome and had more risk factors. Blood pressure: 19% had elevated systolic blood pressure; 4% had elevated diastolic blood pressure. Glycemia: 14% had impaired fasting glucose levels; no diabetes cases were detected. Lipid profile: 26% had high total cholesterol (>170 mg/dL), 20% had high low-density lipoprotein (>110 mg/dL), 13% had high triglycerides (>150 mg/dL), 43% had low high-density lipoprotein (females, <50 mg/dL; males, <40 mg/dL). Ethnicity, gender, and grade level were not predictive of risk except that fewer black children had low high-density lipoprotein, and blood pressure and body mass index increased with grade, as expected. CONCLUSIONS: Results from this study indicate a significant problem with overweight and cardiovascular risk in rural schoolchildren. Notably, younger children were just as likely to have risk factors as adolescents, suggesting that screening and intervention ought to begin by school age. Ethnic and gender differences in prevalence were not found, suggesting that contextual factors in a rural setting may outweigh demographic influences on risk.