There were potentially five questionnaires a participant could have completed around the time he/she entered the trial: the Baseline Questionnaire, the Supplemental Questionnaire, the Dietary Questionnaire, the Diet History Questionnaire and the Medication Use Questionnaire.
Diet History (DHQ)
The Diet History Questionnaire (DHQ) contains dietary information similar to that found in the DQX. 77% of all participants in both arms of the trial completed the DHQ. The form was introduced 5 years into the trial (December 1998). Raw questionnaire responses were processed into analysis-ready variables in terms of gram intake, pyramid servings, food frequencies per day, etc.
Participants in the control arm randomized prior to December 1998 were offered the DHQ in 1999 or 2000, generally around the anniversary of randomization in either year. Control arm participants randomized in/after December 1998 were offered the DHQ at baseline.
Participants in the intervention arm who were randomized prior to December 1995 were offered the DHQ in 1999, generally around the anniversary of randomization. Intervention arm participants randomized in/after December 1995 (third anniversary in/after December 1998) were offered the DHQ generally around their third anniversary of randomization (T3).
DHQ data can be obtained in the DHQ dataset.
|Time of Data Acquisition|