a1 Department of Nutrition, School of Public Health, Loma Linda University, 24785 Stewart Street, EH 203, Loma Linda, CA 92350, USA
a2 Department of Epidemiology and Biostatistics, School of Public Health, Loma Linda University, Loma Linda, CA, USA
a3 Department of Health Promotion and Education, School of Public Health, Loma Linda University, Loma Linda, CA, USA
a4 Adventist Health Study-2, School of Public Health, Loma Linda University, Loma Linda, CA, USA
Objective To assess race-specific validity of food and food group intakes measured using an FFQ.
Design Calibration study participants were randomly selected from the Adventist Health Study-2 (AHS-2) cohort by church, and then by subject-within-church. Intakes of forty-seven foods and food groups were assessed using an FFQ and then compared with intake estimates measured using six 24 h dietary recalls (24HDR). We used two approaches to assess the validity of the questionnaire: (i) cross-classification by quartile and (ii) de-attenuated correlation coefficients.
Setting Seventh-day Adventist church members geographically spread throughout the USA and Canada.
Subjects Members of the AHS-2 calibration study (550 whites and 461 blacks).
Results The proportion of participants with exact quartile agreement in the FFQ and 24HDR averaged 46 % (range: 29–87 %) in whites and 44 % (range: 25–88 %) in blacks. The proportion of quartile gross misclassification ranged from 1 % to 11 % in whites and from 1 % to 15 % in blacks. De-attenuated validity correlations averaged 0·59 in whites and 0·48 in blacks. Of the forty-seven foods and food groups, forty-three in whites and thirty-three in blacks had validity correlations >0·4.
Conclusions The AHS-2 questionnaire has good validity for most foods in both races; however, validity correlations tend to be higher in whites than in blacks.
(Received August 23 2010)
(Accepted February 25 2011)
(Online publication May 06 2011)