Skip to Main Content

An official website of the United States government

Participants Years enrollment close-out today
Baseline Questionnaire (BQ) ~154,000 1993-2001
Dietary Questionnaire I-only (DQX) ~63,000 1993-2001
Diet History Questionnaire (DHQ) ~119,000 1998-2004
Supplemental Questionnaire (SQX) ~104,000 2006-2007
Medical Use Questionnaire (MUQ) ~60,000 2013
Brief Survey (BCQ) ~47,000 2017-2018
Collection of Cancers
Collection of Mortality

Supplemental (SQX)

A Supplemental Questionnaire (SQX) was introduced in 2006, 13 years into the trial. The contents of this questionnaire largely overlap with information collected on the baseline questionnaire (BQ). Some of the overlapping information is data that would not be expected to change between the BQ and the SQX (e.g. race-ethnicity). Other variables may reasonably change between the two questionnaires (e.g. marital status, smoking status, diseases). The SQX additionally contains some data not collected on the BQ (e.g., physical activity).

Ultimately, about 104,000 questionnaires were collected. Given the late administration of the SQX, the median time in the trial following a completion of this form is 3 years.

SQX data can be obtained in the SQX dataset

Summary Available Data
  • Participant-reported data
  • Covers ~104,000 participants
  • Introduced in 2006
  • Median time into study collected: 9 years
  • Median time remaining after collection: 3 years
  • Forms used:
  • Form completion details
  • Demographics
  • Family history
  • BMI and physical activity
  • Health history and Medication
  • Smoking history
  • Female-specific information
  • Male-specific information