Women's use of hormone therapy before and after the Women's Health Initiative: a psychosocial model of stability and change.

Objective: This longitudinal study examined factors underlying hormone therapy (HT) use before and after termination of the landmark Women's Health Initiative (WHI) estrogen plus progestin HT trial in July 2002, after which dramatic reductions in HT use occurred.

Methods: A community sample of 324 women (aged 40-86) from Arizona was interviewed four times between 1995 and 2003. A model of medical and psychological factors underlying intentions for long-term HT use expressed in 1995/1996 was developed and employed to predict subsequent use and discontinued use pre- and post-WHI.

Results: Philosophy of menopause and perceived susceptibility to breast cancer predicted perceived benefits of and barriers to long-term HT use, beyond age, oophorectomy, and physician recommendation. Age, benefits, and barriers predicted intentions for long-term HT use over and above current use. Intentions predicted use 3 years later, controlling for previous use. HT use in 1995/1996 predicted use until the WHI announcement, but not thereafter. Oophorectomy predicted continued HT use before WHI trial termination; perceived barriers, expressed 8 years earlier, predicted discontinued use after WHI trial termination.

Conclusions: Medical and psychological factors predicted sustained and discontinued HT use before and after the WHI announcement. The WHI findings apparently activated potential barriers to use expressed almost a decade earlier.