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

Abstract

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-errorsensitive 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. Keywords Validation Relative validation Epidemiological methods Dietary assessmentValidation and relative validation studies of dietary reporting methods are conducted to evaluate the extent to which those methods elicit accurate reports; this involves comparing reports obtained by such methods as 24-hour recalls and food-frequency questionnaires (FFQs) with reference information obtained by such methods as direct observation, duplicate portion collection or food records. The reported and reference information each consist of a set of food items and their respective amounts. (Table 1 shows terms used in this article and their definitions.) Assessment of reporting accuracy for a group of participants often begins with converting both reported and reference information to energy and nutrients. After cumulating, for each participant, the energy and nutrients within each set, analyses involve several descriptive measures and inferential tests (see e.g. references 1-14). First, paired t-tests may be used to compare the mean of the participant-specific differences between reported and reference energy and nutrients with 0. Second, th...

A Validation Study Concerning the Effects of Interview Content, Retention Interval, and Grade on Children's Recall Accuracy for Dietary Intake and/or Physical Activity

“…15,18-20,25,36 Children’s accuracy for reporting energy intake (in kilocalories) was assessed as in past studies. 50-55 For each observed and/or reported item, the Nutrition Data System for Research database was used to obtain kilocalories for standard school-meal portions. For each match, (a) the reported amount corresponded exactly to the observed amount, (b) the reported amount corresponded to part of the observed amount and the rest of the observed amount was unreported, or (c) part of the reported amount corresponded to the observed amount and the rest was over-reported.…”

Effectiveness of Prompts on Fourth-Grade Children–s Dietary Recall Accuracy Depends on Retention Interval and Varies by Gender

“…For each reported item, the NDSR database was used to obtain kilocalories for a standard school-meal portion. ChildrenÕs accuracy for reporting energy (kilocalorie) intake was assessed as in past studies (23,25,(48)(49)(50)(51). For each match, either 1) the reported amount corresponded exactly to the observed amount, 2) the reported amount corresponded to part of the observed amount and the rest of the observed amount was unreported, or 3) part of the reported amount corresponded to the observed amount and the rest was over-reported.…”

“…Inflation ratio would be 0% if no parts of matches were over-reported and there were no intrusions; inflation ratio has no upper bound (because there is no limit on what a child can report) and smaller values indicate better accuracy. Correspondence rate and inflation ratio sum to the frequently reported ratio of reported energy to observed energy(51).…”

Dietitian-Observed Macronutrient Intakes of Young Skill and Team-Sport Athletes: Adequacy of Pre, During, and Postexercise Nutrition

“…Instead of using food frequency questionnaires or food records, we conducted dietary observations to more accurately (Conway, Ingwersen, & Moshfegh, 2004;McPherson et al, 2000;Mertz, 1992;Rumbold et al, 2011;Smith et al, 2007) determine what the athletes actually consumed before, during, and after practices and competitions. However, since only one day of dietary intake was observed it is possible that the results may not represent the athletes' usual energy, carbohydrate, or protein intake.…”

“…Furthermore, direct observation of meals is more accurate than recall methods because it is not dependent on the subjects' memory. In fact, observations are often used as the gold standard method by which dietary assessment tools are validated in studies with children and adolescents (McPherson et al, 2000;Mertz, 1992;Rumbold et al, 2011;Smith et al, 2007). Therefore, the aim of the current study was to have trained dietitians observe the 24-hr dietary intake of 14-to 19-year-old highly active, competitive skill/team-sport athletes under free-living conditions and compare macronutrient intake to that recommended before, during, and after practice/ competition as well as in a 24-hr period.…”