Use of hormone replacement therapy, 1998-2007: sustained impact of the Women's Health Initiative findings.

Background: Trials of hormone replacement therapy (HRT) for prevention of chronic disease in postmenopausal women have suggested that the risks of treatment outweigh the benefits. The publication in 2002 of the Women's Health Initiative (WHI) study sparked a rapid decline in HRT purchases among American women.

Objective: To examine the impact of the WHI findings on patterns of HRT use in Israeli women.

Methods: We linked purchases of estrogen preparations from 1998 to 2007 by female Israeli health maintenance organization members aged 45 years and older to membership data. For each year, we calculated total annual purchases and rate of HRT utilization, characterized new users by age and mode of therapy, and examined rates of switching between modes of therapy.

Results: Twenty percent of women aged 45 years and older purchased estrogen products in 2001, versus 10% in 2007 (p < 0.001; chi(2)). Vaginally administered products accounted for a rising percentage of purchases, from 5% in 1999 to 18% in 2007. An increasing percentage of new users aged 55 years and older started with a vaginal product (62% in 1999, 82% in 2007). After 2002, new users of oral therapy discontinued use more quickly than those who started oral therapy before 2002. Tibolone accounted for an increasing percentage of oral drugs purchased (12% in 2003, 29% in 2007).

Conclusions: The WHI findings had a rapid and sustained impact on HRT utilization in a large population of Israeli women, including a sharp decrease in the rate of use, particularly of oral preparations, as well as reduced duration of therapy and increased use of vaginal preparations and tibolone as first choices for treatment.