Several migraine screening tools have been tested, including two seminal questionnaires dating back to the 1990s [49, 50], the Migraine Screen Questionnaire (MS-Q) [51], the deCODE Migraine Questionnaire (DMQ3) [52], a German questionnaire [53], and the Structured Migraine Interview (SMI) [54].
In many questionnaires dating is done by starting with a screening question that investigates if the respondent has been a victim in the preceding 5 years and followed by a more precise question about the incidence in the last 12 months.
The reference date for WHI is the baseline questionnaire date.
Assessments were performed at baseline and at 6 months from the first questionnaire date.
For instance, our questionnaire asked subjects their travel behaviors in the past 3 months of their pregnancy trimester before the questionnaire date while the GPS tracked their time-location patterns one week following the questionnaire date.
This would be registered as a cardiac readmission or event shortly after the initial PCI and could have taken place after the questionnaire date.
We assigned to each child an estimate of regional PM10 for the year preceding the questionnaire date, obtained from one fixed monitoring station in each community.
Baseline FEV1 for a subject was defined as the average FEV1 of all measurements obtained the 12 months preceding or after the exercise questionnaire date.
35 For analysis of the primary outcome, participants contributed to person time up to the date of diagnosis, date of last completed questionnaire, date of death, or 1 July 2009, whichever occurred first.
Person-years were calculated from the date of the baseline prostate cancer screening to the date of the most recently completed annual follow-up questionnaire, date of diagnosis, death, or 30 September 2002, whichever came first.
