COMPARISON OF CONTINUATION OF POSTMENOPAUSAL HORMONE REPLACEMENT THERAPY - TRANSDERMAL VERSUS ORAL ESTROGEN

Objective: To determine possible differences in the rate at which horm one replacement therapy (HRT) is continued among postmenopausal women treated initially with transdermal estradiol versus those treated init ially with oral conjugated estrogens. Design: A retrospective database search for prescription use. Setting: Northern California facilities of Kaiser Permanente, a health maintenance organization, Patients: Wom en aged greater than or equal to 45 years who filled index prescriptio ns for HRT during 1995 for either 0.05 mg transdermal estradiol semiwe ekly or 0.625 mg oral conjugated estrogen daily, All had filled prescr iptions for medroxyprogesterone acetate (MPA) on the same day as the i ndex estrogen prescription. Results: We found statistically significan tly greater relative risk (RR) of discontinuation among women whose HR T began with transdermal estradiol compared with women whose HRT began with oral conjugated estrogens [RR = 2.6, 95% confidence interval (CI ) = 1.8-3.8]. After multiple adjustments, RR was 2.7 (95% CI =; 1.8-3. 9). Complete discontinuation of HRT treatment accounted for most of th e stopping we observed, but more women switched from transdermal to or al (25% of those discontinuing this route) than switched from oral to transdermal (0.9% of those discontinuing this route). Risk of disconti nuation was not associated with whether prescriber was a gynecologist (RR = 1.2, 95% CI = 0.9-1.7), Type of progestin schedule (cyclic vs, c ontinuous combined) also was not a predictor for discontinuation (RR = 0.9, 95% CI = 0.8-1.0). Older age at start of treatment was associate d with discontinuation (RR = 1.1, 95% CI = 1.0-1.2) for every addition al 5 years of age. Conclusion: Among women starting HRT, those using a semiweekly transdermal estradiol regimen have a lower rate of continu ation than do those using oral estrogen daily. (Menopause 1998;5:152-1 56, (C) 1998, The North American Menopause Society.