Determinants of hormone replacement therapy duration among postmenopausal women with intact uteri

Objective: To investigate factors associated with hormone replacement therapy (HRT) duration among postmenopausal women with intact uteri. Design: A Cox proportional hazard model on time to HRT discontinuation is estimated for 2,632 postmenopausal HRT users with intact uteri who began a new episode of treatment between January 1990 and December 1994 in Saskatchewan, Canada. Results: Major contraindicating medical events were highly associated with HRT discontinuation among postmenopausal women. Women who were diagnosed with uterine cancer while taking HRT were almost four times as likely to discontinue HRT, and women who were diagnosed with breast cancer while taking HRT were nearly five times as likely to discontinue HRT. Other statistically significant factors associated with the duration of HRT episodes include administration mode and the ability to try different types and strengths of HRT. Women initiating HRT with a transdermal patch were 50% more likely to discontinue it. Women who were willing and able to experiment with different HRT reduced their likelihood of discontinuing by one-half to three-fourths. Conclusions: Although some of the factors associated with the hazard of HRT discontinuation among postmenopausal women who are taking the treatment for preventive benefits are immutable, clinicians may influence HRT continuation rates through initial drug choice or modifications in drug type or regimen over the course of therapy.