Looking for the current Canadian version of DHQ?
When was the DHQ evaluated?
All evaluation studies for the Diet History Questionnaire (DHQ) developed by the National Cancer Institute (NCI) were conducted using DHQ I. Given that DHQ II and DHQ III were created using methods identical to those used for DHQ I, it is presumed that evaluation studies would yield similar results if conducted in like populations. NCI has no plans to do any further evaluation research.
How generalizable is the DHQ to your study population?
As the DHQ was designed from a general population national dietary survey, the reference data and validation are representative of the entire U.S. adult population. Therefore, validation of DHQ III may vary for specific population groups.
Note that modifying the questionnaire may result in changes to validity of the instrument. Small changes are unlikely to affect validation substantially, but if you make many changes to the DHQ, the published validation research may not apply to your new instrument. This may also be true if you are administering the DHQ in specific populations. Modifications made to the DHQ III should be reported in the methods section of any publication for which it is used.
How does the DHQ compare to other food frequency questionnaires (FFQs)?
Findings from DHQ I evaluations studies show that the instrument provides nutrient estimates similar to most comprehensive FFQs. Three studies were conducted to assess its validity/calibration:
- The first validation study used a checklist approach. The resulting data showed that most of the cognitive enhancements incorporated in the DHQ I were an improvement over the 1992 NCI/Block questionnaire for frequency, an FFQ commonly used at the time.
- The second validation study, conducted in 1997-1998, compared the DHQ I instrument to two FFQs available at that time -- the 1995 Block and Willett (purple version) food frequency questionnaires. The validation used four 24-hour dietary recalls (one in each season) as reference data. The study showed the DHQ to be as good as or superior to these Block and Willett instruments for most nutrients. (Please note: The Block and Willett questionnaires used in this validation are not the current versions of these FFQs.)
- The third study compared intake of absolute energy and protein estimated on the DHQ I with unbiased biomarkers of intake: doubly labeled water (for energy expenditure) and urinary nitrogen (for protein). The Observing Protein and Energy Nutrition (OPEN) Study showed significant underreporting and measurement error for the DHQ I. There is a descriptive publication of these results, as well as a publication that is more statistical in nature.