a1 Personal Improvement Computer Systems, Inc., Reston, VA, USA
a2 Correspondence address: Center for Health Studies, 1730 Minor Avenue Suite 1600, Seattle, WA 98101-1401, USA.
a3 Current affiliations: J.M.B. – Center for Health Studies Group Health Cooperative, Seattle, WA, USA; A.D. – George Washington University, School of Public Health, Washington, DC, USA; W.T.R. – National Institute of Mental Health, Bethesda, MD, USA.
Objective To develop and evaluate a pictorial, web-based version of the NCI diet history questionnaire (Web-PDHQ).
Design The Web-PDHQ and paper version of the DHQ (Paper-DHQ) were administered 4 weeks apart with 218 participants randomised to order. Dietary data from the Web-PDHQ and Paper-DHQ were validated using a randomly selected 4 d food record recording period (including a weekend day) and two randomly selected 24 h dietary recalls during the 4 weeks intervening between these two diet history administrations.
Setting Research office in Reston, VA, USA.
Participa414ts Computer-literate men and women recruited through newspaper advertisements.
Results Mean correlation of energy and the twenty-five examined nutrients between the Web-PDHQ and Paper-DHQ was 0·71 and 0·51, unadjusted and energy-adjusted by the residual method, respectively. Moderate mean correlations (unadjusted 0·41 and 0·38; energy-adjusted 0·41 and 0·34) were obtained between both the Web-PDHQ and Paper-DHQ with the 4 d food record on energy and nutrients, but the correlations between the Web-PDHQ and Paper-DHQ with the 24 h recalls were modest (unadjusted 0·31 and 0·29; energy-adjusted 0·37 and 0·26). A subset of participants (n 48) completing the Web-PDHQ at the initial visit performed a retest on the same questionnaire 1 week later to determine repeatability, and the unadjusted mean correlation was 0·82.
Conclusions These data indicate that the Web-PDHQ has comparable repeatability and validity to the Paper-DHQ but did not improve the relationship of the DHQ to other food intake measures (e.g. food records, 24 h recall).
(Received March 29 2007)
(Accepted April 16 2008)