Participants completed a baseline evaluation between January 1994 and August 2002, and were followed with annual clinical evaluations for up to 8 years. 97% of eligible participants completed at least two follow-up evaluations (mean number of evaluations per person = 6; range: 2 - 9).
At baseline, women were asked about current and past hormone therapy use (ever v. never), age of initiation of hormone therapy, as well as age at which they stopped. Current use of hormone therapy was verified by inventory of prescription bottles that participants brought to the interview, and agreement was 93%. 36% of the females reported using estrogen (either past or present use).
The main analysis in this paper assessed the association between gender and risk of AD. We obtained the results for the duration of hormone therapy and AD risk via a personal communication. The exposure distribution by category of duration is not reported.
The results reported here compare duration of HRT use (< 10 years, ≥ 10 years) to no HRT use.
Ethnicity data are given as percentages of the total cohort, not just the women. 779 were white, 62 were black, 5 were Asian/Pacific Islander, and 2 were American Indian.
At the baseline evaluation, the mean age was 76.1 years.
In order to be eligible for the study, participants had to be free of clinical evidence of AD or dementia at baseline. The annual clinical evaluation included a medical history, neurologic examination, and cognitive function assessments.
The AD diagnosis was made by a board-certified neurologist and was based on NINCDS-ADRDA criteria.
These results were obtained from a personal communication with the study author.