Validation of a semi-quantitative food frequency questionnaire to assess food groups and nutrient intake.

ABSTRACT

INTRODUCTION: Semi-quantitative Food Frequency Questionnaires (FFQs) analyze average food and nutrient intake over extended periods to associate habitual dietary intake with health problems and chronic diseases. A tool of this nature applicable to both women and men is not presently available in Mexico. OBJECTIVE: To validate a FFQ for adult men and women. METHODS: The study was conducted on 97 participants, 61% were women. Two FFQs were administered (with a one-year interval) to measure reproducibility. To assess validity, the second FFQ was compared against dietary record (DR) covering nine days. Statistical analyses included Pearson correlations and Intraclass Correlation Coefficients (ICC). The de-attenuation of the ICC resulting from intraindividual variability was controlled. The validity analysis was complemented by comparing the classification ability of FFQ to that of DR through concordance between intake categories and Bland-Altman plots. RESULTS: Reproducibility ICC values for food groups ranged 0.42-0.87; the range for energy and nutrients was between 0.34 and 0.82. VALIDITY ICC values for food groups ranged 0.35-0.84; the range for energy and nutrients was between 0.36 and 0.77. Most subjects (56.7-76.3%) classified in the same or adjacent quintile for energy and nutrients using both methods. Extreme misclassification was <6.3% for all items. Bland-Altman plots reveal high concordance between FFQ and DR. CONCLUSIONS: FFQ produced sufficient levels of reproducibility and validity to determine average daily intake over one year. These results will enable the analysis of possible associations with chronic diseases and dietary diagnoses in adult populations of men and women.

RESUMEN

Introducción. Los cuestionarios semicuantitativos de frecuencia de consumo (CFC) analizan ingestión promedio de alimentos y nutrimentos en períodos extensos para asociar consumo habitual con problemas de salud, como enfermedades crónicas. En México, no existe una herramienta similar, aplicable en mujeres y hombres. Objetivo. Validar un CFC en mujeres y hombres adultos. Métodos. El estudio incluyó 97 participantes (61% mujeres). Dos CFC fueron aplicados (un año entre ambos) para medir reproducibilidad. Para validez, se comparó el segundo CFC con registros dietéticos de nueve días. Los análisis incluyeron correlaciones de Pearson y coeficientes de correlación intraclase (CCI). Se controló desatenuación de CCI provocada por la variabilidad intraindividual. El análisis de validez se complementó con la comparación de la capacidad de clasificación entre CFC y registros dietéticos, mediante concordancia de categorías de consumo y gráficos de Bland y Altman. Resultados. Reproducibilidad los CCI para grupos de alimentos oscilaron entre 0.42-0.87 y para nutrimentos entre 0.34-0.82. Validez los CCI para grupos de alimentos variaron entre 0.35-0.84 y para nutrimentos entre 0.36-0.77. La mayoría de sujetos (56.7-76.3%) clasificaron en el mismo quintil o adyacente por ambos métodos (media 66.1%), para nutrimentos. La mala clasificación extrema para todos los ítems fue.