TY - JOUR
T1 - Design and quality control issues related to dietary assessment, randomized clinical trials and meta-analysis of field-based studies in developing countries
AU - Gibson, Rosalind S.
AU - Sazawal, Sunil
AU - Peerson, Janet M.
PY - 2003/5/1
Y1 - 2003/5/1
N2 - The essential design and quality control aspects of dietary assessment, randomized controlled trials (RCT) in developing countries and their subsequent meta-analysis are reviewed. Dietary assessment protocols consist of three stages: measurement of food intakes using a method appropriate for the study objectives, calculation of nutrient intakes and finally an evaluation of their nutrient adequacy. The latter may involve: 1) assessment of dietary diversity (average number of different foods consumed per day) and selected indices of dietary quality such as intakes of animal source foods (g/d); 2) percentage of energy from protein, fat and animal protein; 3) selected nutrient densities; and 4) dietary phytate:zinc molar ratio, as well as the prevalence of inadequate nutrient intakes calculated using a probability approach. To establish causality between the nutrient inadequacies identified and adverse health outcomes, RCT must be undertaken. A prerequisite of RCT is double-blind randomization, a procedure designed to eliminate biases arising from baseline confounding variables, unintended interventions and ascertainment bias. Results from existing RCT can be summarized via meta-analysis to gain a better understanding of the population relationship. Meta-analysis is a statistical technique involving linear models or generalized linear models, which can be performed after locating the individual studies, and selecting and abstracting all the necessary data.
AB - The essential design and quality control aspects of dietary assessment, randomized controlled trials (RCT) in developing countries and their subsequent meta-analysis are reviewed. Dietary assessment protocols consist of three stages: measurement of food intakes using a method appropriate for the study objectives, calculation of nutrient intakes and finally an evaluation of their nutrient adequacy. The latter may involve: 1) assessment of dietary diversity (average number of different foods consumed per day) and selected indices of dietary quality such as intakes of animal source foods (g/d); 2) percentage of energy from protein, fat and animal protein; 3) selected nutrient densities; and 4) dietary phytate:zinc molar ratio, as well as the prevalence of inadequate nutrient intakes calculated using a probability approach. To establish causality between the nutrient inadequacies identified and adverse health outcomes, RCT must be undertaken. A prerequisite of RCT is double-blind randomization, a procedure designed to eliminate biases arising from baseline confounding variables, unintended interventions and ascertainment bias. Results from existing RCT can be summarized via meta-analysis to gain a better understanding of the population relationship. Meta-analysis is a statistical technique involving linear models or generalized linear models, which can be performed after locating the individual studies, and selecting and abstracting all the necessary data.
KW - Dietary assessment
KW - Double blinding
KW - Meta-analysis
KW - Probability analysis
KW - Randomized clinical trials
UR - http://www.scopus.com/inward/record.url?scp=0038670665&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0038670665&partnerID=8YFLogxK
U2 - 10.1093/jn/133.5.1569s
DO - 10.1093/jn/133.5.1569s
M3 - Article
C2 - 12730468
AN - SCOPUS:0038670665
VL - 133
SP - 1569S-1573S
JO - Journal of Nutrition
JF - Journal of Nutrition
SN - 0022-3166
IS - 5 SUPPL. 2
ER -