Background on Diet History Questionnaire II (DHQ-II) for U.S. & Canada

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• Diet History Questionnaire II: Background
• Canadian Diet History Questionnaire II: Background

Diet History Questionnaire II: Background

The Diet History Questionnaire (DHQ) is a freely available food frequency questionnaire (FFQ) developed by staff at the Risk Factor Assessment Branch (RFAB). It can be used by researchers, clinicians, or teachers without permission.

The original DHQ I was designed based on cognitive research findings, to be easy to use. It had 124 food items and included both portion size and dietary supplement questions.

The DHQ II has a food list that was updated based on more recent dietary data and consists of 134 food items and 8 dietary supplement questions (list of changes between DHQ I and DHQ II).

Early testing showed that the paper-and-pencil version of DHQ I took about 1 hour to complete. No testing has been done on the DHQ II but we assume completion times are similar. Our web based versions, however, are likely to take less time to complete. Unlike, DHQ I, there are four different versions of DHQ II, in both paper and electronic formats (DHQ*Web). These four versions differ by time frame and portion size questions:

1. Past year, with portion size (our standard FFQ format): asks about intake in the past year and includes questions about portion size.
2. Past year, without portion size: asks about usual intake in the past year and excludes questions about portion size.
3. Past month, with portion size: asks about intake in the past month and includes questions about portion size.
4. Past month, without portion size: asks about usual intake in the past month and excludes questions about portion size.

Data from two relatively old studies conducted to assess validity showed that the DHQ I (past year time frame, with portion size questions) provided reasonable nutrient estimates. The first, using a checklist approach, showed that many of the cognitive improvements introduced in the DHQ I provided a better measure of frequency than the 1992 Block FFQ. The second validation, which compared the DHQ I to two FFQs that were widely used at the time the study was conducted (the 1995 Block FFQ and the "purple version" of the Willett FFQ), showed the DHQ I to be as good as or superior to those instruments for most nutrients.

There are no plans to validate the updated DHQ II, however, there are few major changes to the overall food list. The effects of excluding portion size or asking about the past month versus the past year have not been evaluated. We recommend you ask portion size questions in cases when the FFQ is your primary dietary assessment instrument. However, data from any version of the DHQ could be used as a covariate in models that use the NCI Method to assess usual intakes when 24-hour dietary recalls or food records are the primary dietary assessment instrument tools.

The food list and nutrient/food group database used with the DHQ are based on national dietary data (the National Health and Nutrition Examination Surveys (NHANES) data collection in 2001-2002, 2003-2004, 2005-2006).

DHQ III is the current version of the questionnaire distributed by the NCI for U.S. populations; however, DHQ III does not yet have a Canadian version. The Canadian version of DHQ II is still available.

You may analyze DHQ II data from either the paper or electronic forms with the Diet*Calc software developed by the NCI. Diet*Calc may be used to analyze data files from both the paper and electronic DHQ II modes of administration.

To use Diet*Calc, an ASCII text file containing data from completed DHQs must be created from paper-based forms or obtained from DHQ*Web. Diet*Calc will interpret the DHQ data to provide nutrient and food group intake estimates.

Canadian Diet History Questionnaire II: Background

A Canadian Diet History Questionnaire II (C-DHQ II) is also freely available for use by researchers, clinicians and teachers. Modifications to the original US DHQ II were made by a coalition of Canadian investigators from academia, government and research.

Modifications to the original DHQ II were made to better reflect Canadian diets that are modestly different from the US owing to differences in food availability and fortification practices. The C-DHQ II food list was based on analyses of 24-hour dietary recalls reported by adults surveyed in the national Canadian Community Health Survey, Cycle 2.2, Nutrition (2004) (CCHS), Statistics Canada.

The C-DHQ II queries 165 questions of which 153 are food questions, 10 questions are related to nutritional supplement use (vitamins, minerals and herbal supplements), one question asks about the cooking of meat and one asks about vegetarian diets. One hundred and forty-three food questions are queried with portion sizes. Fifty-three of these questions which were also on the NCI DHQ II were modified for portion size amounts in at least one of the three portion size categories. Other modifications were made to the text to reflect Canadian vernacular. (Summary of Differences between NCI DHQ II and C-DHQ II; Summary of Differences between the the C-DHQ I and C-DHQ II.) The C-DHQ II (English and French) is available in both paper and electronic formats (DHQ*Web), in two versions that differ by time frame:

1. Past year, with portion size (our standard FFQ format): asks about intake in the past year and includes questions about portion size.
2. Past month, with portion size: asks about intake in the past month and includes questions about portion size.

Methods used to identify the C-DHQ II food list and to generate the nutrient/food group database were similar to those described by Dr. Subar and colleagues in the development of the US DHQ II except that CCHS food consumption data were used instead of National Health and Nutrition Examination Surveys (NHANES) data. While the majority of decisions pertaining to the inclusion and exclusion of food and beverage questions were based on analyses of CCHS data, foods more recently added to the Canadian market were also evaluated and where appropriate added to questions on the C-DHQ II (e.g., bottled water with added vitamins and minerals). In addition, Canadian investigators external to the core working group were consulted to advise on the inclusion of foods that may be relevant to emerging new hypotheses in nutritional epidemiology and chronic disease research.

The core working group led by Dr. Ilona Csizmadi (Alberta Health Services - CancerControl), comprised of Isabelle Masarelli and Isabelle Rondeau (Food Directorate, Health Canada), Beatrice Boucher (Cancer Care Ontario) and Dr. Anita Koushik (University of Montreal).

Questions about the C-DHQ II may be emailed to dhq@imsweb.com.