a1 Department of Epidemiology and Biostatistics and Center for Research in Nutrition and Health Disparities, Arnold School of Public Health, University of South Carolina, 915 Greene Street, Columbia, SC 29208, USA
a2 School of Nursing and Department of Biostatistics, University of North Carolina, Chapel Hill, NC, USA
a3 Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA
a4 Department of Nutrition and Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
a5 Department of Nutritional Sciences, University of Cincinnati Medical Center, Cincinnati, OH, USA
a6 Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA
Objective To evaluate the relative validity and reliability of the SEARCH FFQ that was modified from the Block Kids Questionnaire.
Design Study participants completed the eighty-five-item FFQ twice plus three 24 h dietary recalls within one month. We estimated correlations between frequencies obtained from participants with the true usual intake for food groups and nutrients, using a two-part model for episodically consumed foods and measurement error adjustment.
Setting The multi-centre SEARCH for Diabetes in Youth Nutrition Ancillary Study.
Subjects A subgroup of 172 participants aged 10–24 years with type 1 diabetes.
Results The mean correlations, adjusted for measurement error, of food groups and nutrients between the FFQ and true usual intake were 0·41 and 0·38, respectively, with 57 % of food groups and 70 % of nutrients exhibiting correlations >0·35. Correlations were high for low-fat dairy (0·80), sugar-sweetened beverages (0·54), cholesterol (0·59) and saturated fat (0·51), while correlations were poor for high-fibre bread and cereal (0·16) and folate (0·11). Reliability of FFQ intake based on two FFQ administrations was also reasonable, with 54 % of Pearson correlation coefficients ≥0·5. Reliability was high for low-fat dairy (0·7), vegetables (0·6), carbohydrates, fibre, folate and vitamin C (all 0·5), but less than desirable for low-fat poultry and high-fibre bread, cereal, rice and pasta (0·2–0·3).
Conclusions While there is some room for improvement, our findings suggest that the SEARCH FFQ performs quite well for the assessment of many nutrients and food groups in a sample of youth with type 1 diabetes.
(Received May 21 2013)
(Revised January 30 2014)
(Accepted February 07 2014)