||Virtually all known deaths were verified
by death certificate. If a participant was lost to follow-up, their case was censored at
the last known contact. If a respondent was alive at the 1992 follow-up, their case was
censored at the date of interview.
The study of ADL/IADL limitations was restricted to
respondents interviewed (alive) in 1982 and 1992. The dependent variable is a summed scale
of 23 Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL)
items taken from the Stanford Health Assessment Questionnaire. The items are scored from 0
(no difficulty with activity) to 3 (unable to do). The scale has excellent internal
consistency at both time points.