W30 - Dietary assessment study

Investigator Names and Contact Information

Introduction/Intent

The development of FFQs was motivated by the desire for a rapid, inexpensive, and accurate method of assessing usual dietary intake. In WHI, the FFQ is used for several purposes: (1) as a screening tool to determine whether women are eligible (more than 32% of energy from fat) for the DM component, (2) to assess the baseline diet of women in all components of the trial, including the Hormone Replacement Trial (HRT) and the Observational Study (OS), and (3) to evaluate the success of the Dietary Intervention over the course of the trial.

Special considerations required development of a unique FFQ for WHI:

1. The comprehensive assessment of dietary intake needed when disease endpoints include (but are not limited to) breast cancer, cardiovascular disease, colon cancer, and osteoporosis.
2. Adequate low-fat and fat-free modified foods to be sensitive to the low-fat dietary intervention.
3. Inclusion of foods reflecting regional and ethnic eating patterns.

There is a general agreement in the scientific community that FFQs should be validated within specific study populations. Comparison of the nutrient measures from the baseline FFQ to the reference nutrient measures from the 4-repeat 24 Hour Recalls and the 4DFR will allow us to describe and quantify measurement error in the WHI FFQ.

A manuscript that provides a detailed description of the WHI FFQ and its measurement characteristics will be a valuable reference document for all future WHI nutrition publications. We believe that it is important to the WHI that this study be performed and the results published in a timely manner.

Aims

The primary goal of this study is to assess the bias and precision of the Women's Health Initiative (WHI) Food Frequency Questionnaire (FFQ). We will compare nutrient measures from the FFQ with two independent methods of assessing dietary intake: repeat 24-Hour Recalls (24HRs) and Four-Day Food Records (4DFRs).

Secondary Aims

1. Evaluate the sensitivity and specificity of the FFQ as a screening instrument for entry into the Dietary Modification (DM) Trial.
2. Estimate test-retest reliability of the FFQ by comparing nutrient measures from the screening FFQ with a repeat FFQ.

Overview of Protocol

A sample of 160 women will participate in the study; one half will have a baseline FFQ nutrient analysis greater than or equal to 32% energy from fat, and half will have less than 32% energy from fat. If all Vanguard Clinical Centers (VCCs) participate, each clinic will be asked to recruit 10 women.

Women who volunteer for the study will complete the following activities at screening visits (SVs):

SV0/SV1

• Form 60 - Food Questionnaire
• Form 2/3 - Eligibility Screen
• Form 20 - Personal Information

SV1

• DAS Consent Form
• Form 80 - Physical Measurements
• Current Supplements (direct entry or Form 45)

BETWEEN SV1 and SV2

• Another Form 60 - Food Questionnaire
• Four 24-hour dietary telephone recalls

SV2

• Four-Day Food Record Instruction
• Form 34 - Personal Habits

SV3

• Form 62 - Four-Day Food Record

Analyses

The analyses will be based on standard techniques for analysis of validity and reliability studies. We will assess systematic bias in the FFQ (versus the records and recalls) as the difference between the FFQ nutrient measures and the mean measures from the records and recalls. We will assess precision as the Pearson correlation coefficient between the FFQ measures and the records (and recalls).

Results/Findings

See publications: 35. WHI publications by study lists published WHI papers that have been generated by ancillary studies. A complete list of WHI papers is available in the Papers of this website.