History of thyroid disease at baseline is self-reported at the baseline interview.

Participants are asked the following question:

Have you ever been told by a doctor, nurse, or therapist that you had thyroid disease?

Response choices are coded into reported as present prior to baseline = 1 or not reported as present prior to baseline (includes suspect or possible) = 0.

Response choices:

Note: A longitudinal version of this variable is available upon request.