School Age Populations Research Needs - NCS Dietary Assessment Literature Review
"Even after 40 years of research, and a plethora of comparative studies, there are no universal criteria which can be applied when selecting data-collection methods suitable for studies of children and adolescents." Livingston and Robson, 2000 (161)
Drawing conclusions about the validity of available dietary assessment instruments in school age children is hampered by the differences in instruments, research design, reference methods, and populations in the validation literature. Research needs have been identified by a number of authors:
- Studies need to examine the validity and reliability of each dietary assessment method by age, gender, ethnic subgroup, and socioeconomic status to understand the best application of each tool (1).
- Development and validation of improved methods for assessing dietary supplement use are needed (9;64).
- Studies that compare multiple reference measures for a particular reference assessment method would allow comparisons of the validation standards best suited for particular situations (161).
- Physiologically-based measures, such as DLW (Doubly Labeled Water) or serum micronutrient concentrations, merit further study because these reference measures are not affected by respondent error; (1;161;201) a more extensive database of assessments of TEE (Total Energy Expenditure) by the DLW method is needed.
- Identification and characterization of subgroups most likely to misreport food intakes, together with the reasons for doing so, need further study, as does the development of improved techniques to identify underreporters and overreporters at the individual level (161;201).
- The issue of whether underreporting of diet applies to the diet as a whole or whether there is selective underreporting of nutrient intake, whether by food types, meals, or snack foods, needs examination (161).
- The reasons for, and effects of, non-participation by children and adolescents should be examined to identify possible sources of bias (non-response bias) and to assess implications for design analysis and interpretation of results (161;217).
- Developing new or refining existing dietary survey methods that are sensitive to different ages, cognitive abilities and motivation levels and that improve accuracy and are not time consuming is needed (1;160;161;204;205).
- The effect of body size on reporting of dietary intake requires further study (1;161).
- Further research is needed to refine the cognitive model for children's recall of dietary intake proposed by Barnowski and Domel (160) and to address many unresolved issues, such as the impact of time and less experimentally controlled conditions on retention and retrieval processes (161).
- The effects of a longer time lag between meal recall and environmental factors on the accuracy of recall in children need to be established (202).
- The accuracy of child versus parent or caretaker respondents needs further study (165;218).
- New methods for estimating portion sizes that are sensitive to the cognitive abilities of children are needed (1;161;202).
- More research is needed on the prompts that can aid memory retrieval at various ages without increasing the risk of eliciting socially-desirable responses. Environmentally specific probes (e.g., school, fast food restaurants, extracurricular activities, media and entertainment, food industry packaging of foods for children) within a food record or food frequency questionnaire also are needed (160;161;206;218).
- Refinement of statistical techniques to account for systematic bias in pediatric populations is needed. Statistical models need to be developed that will estimate the impact of systematic bias on estimates such as relative risk, variance ratios, or proportions on the populations with inadequate intakes (161).
- Emerging technologies should be applied to developing new dietary assessment methods (e.g., Internet-based self-administered methods or dietary assessment methods that incorporate cellular telephones, personal digital assistants, or video recording) (219).